An agenda item for the 2023 World Radiocommunication Conference (WRC-23) has emerged that proposes consideration of the 144-146 MHz frequency range, including possible reassignment as a primary band application for the aeronautical mobile service, and there is little support for this objected at a meeting of the European Conference of Postal and Telecommunications Administrations (CEPT). The Team A project group where this issue was considered is responsible for some aspects of the CEPT WRC positions and the meeting was held June 17-21 in Prague, Czech Republic. The proposal submitted by France, which aims to reassign the 144-146 MHz amateur radio band, will be part of a broader review of bands for the aeronautical mobile service. Another issue raised at the meeting concerned the sharing of the amateur radio band 1240-1300 MHz with the European GPS Galileo system.

“We have heard that only one administration (Germany) opposed the proposal to reassign the 144 MHz amateur radio band – and no one else,” a UK Microwave Group spokesman said after the meeting. Otherwise, this agenda item would have been moved to the CEPT Conference Preparatory Group (CPG) meeting in August.

The International Amateur Radio Union (IARU), which was represented at the Prague meeting, expressed "serious concerns" about any proposal that would include consideration of the 144-146 MHz band for the aeronautical mobile service in the proposed agenda item. Moreover, at the conference they intend to consider the issue of reassigning the entire 2-meter band in the 1st ITU Region. The IARU is committed to making every effort to fully protect the interests of amateur radio stations and to secure the support of the necessary regulators for their representation.

IARU Region 1 President Don Beattie, G3BJ, stated before the meeting that the IARU would “vigorously promote its opposition within the Regional Telecommunications Organizations (RTOs) and the International Telecommunications Union (ITU) to obtain assurances that “that this range will remain the main one for radio amateurs.”

The 144-146 MHz band in the worldwide frequency allocation is the only VHF band assigned to the amateur and amateur-satellite services on a primary basis. This widely used segment of the amateur radio bands is used by a large number of users, repeaters and satellite stations, including the ISS.

According to the minutes of the meeting, the proposal does not provide a rationale for redefining 144-146 MHz, and the IARU believes that sharing with airborne systems is likely to be difficult and will limit the development of amateur and amateur satellite services in this band. The IARU recommended that alternative proposals be developed that could provide additional radio frequency space for aviation applications without hanging the “sword of Damocles” over the “double” radio amateurs.

The IARU is expected to inform community members to discuss the French proposal with their governments before the August CEPT-CPG meeting. And France could try to introduce the same proposal to study 144 - 146 MHz for aviation use in other RTOs.

Meanwhile, further discussion is expected before the meeting in August preparatory group proposals for studying the 23-centimeter range. The proposal was put forward following reports of interference with the Galileo navigation system, but the IARU said it was aware of only "a few cases" of interference with Galileo's E6 signal on 1278.750 MHz. In the meantime, work on this issue will continue in other specialized CEPT forums.

American radio amateurs use the following calling frequencies for DXpeditions (in kHz):

• 1828.5,
• 3505,
• 7005,
• 7065,
• 10110,
• 14025,
• 14195,
• 18075,
• 18145,
• 21025,
• 21295,
• 24895,
• 24945,
• 28025,
• 28495.

Calling frequencies for QRP stations (in kHz):

• 1810,
• 3560,
• 10106,
• 14060,
• 14285,
• 21060,
• 21385,
• 28060,
• 28385.

In Europe and some other countries, the following frequencies (kHz) are recommended for low power operation (QRP) in SSB mode:

• 3690,
• 7090,
• 14285,
• 21285.

For telegraph (in kHz):

• 1843,
• 3560,
• 7030,
• 10106,
• 14060,
• 18096,
• 21060,
• 24906,
• 28060.

Frequencies for DXpeditions in Europe have not yet been agreed upon.

SSB-QRP round tables conducted on 3620 kHz at 18:30 MEZ (MES).

Western radio amateurs, supporting the SOTA program, use frequencies (kHz):

• 7030,
• 7060,
• 14060,
• 14285,
• 145575 (FM),
• 144285 (SSB),
• 430150,
• 430475 (FM),
• 432200 (SSB).

In Russia, fans of the RDA program (working “through fractions”) can usually be found around the frequency of 14180 kHz ±QRM.

The frequencies for mountain expeditions under the RMA program are not precisely specified, so mountain radio amateurs use the standard frequencies intended for DXpeditions and QRP, described above.

Frequencies in Moscow and the Moscow region

MIA frequencies

148-149 MHz - 25 kHz step (NFM mode).

148.2250 and 148.9500 - MUVD channel on railway transport.

171-173 MHz - step 25 (NFM mode)

171.7250 and 171.7500 - duty station of the Moscow Main Internal Affairs Directorate.

171.7750 and 172.3250 - special channel of the Moscow Main Internal Affairs Directorate.

172.3000 and 172.2750 - duty station of the Moscow Main Internal Affairs Directorate.

205.100 - frequency of the State Traffic Inspectorate of the Moscow City Internal Affairs Directorate.

450-453 MHz - step 12.5 (NFM)

450.3000 450.3750 450.4750 450.5000 450.5705

450.6250 450.6500 450.6750

451.0500 451.1500

451.3000 451.4000

451.5250 and 451.5375 - scrambling.

452.4250 452.5875 452.6200

460-463 MHz - step 12.5 (NFM mode)

460.8000 and 461.4500 - scrambling.

461.0000 - special communication channel of the Ministry of Internal Affairs of the Russian Federation.

Ministry of Defense of the Russian Federation

Frequency ranges of the Russian Ministry of Defense:

• 254.000,
• 254.685,
• 380.000,
• 393.100.

FAPSI

• 148-149 (step 1) - the radio frequency band is intended for primary use by radio communications of the Ministry of Internal Affairs of the Russian Federation.
• 149-149.9 (step 0.9) - the radio frequency band is intended for use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 157.875 - FAPSI special purpose channel.
• 162.7625-163.2 (step 0.4375) - the radio frequency band is intended for use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 168.5-171.15 (step 2.65) - the radio frequency band is intended for use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 169.455 and 169.462 are FAPSI special purpose channels.
• 171.15-173 (step 1.85) - the radio frequency band is intended for primary use by radio communications of the Ministry of Internal Affairs of the Russian Federation.
• 173-174 (step 1) - the radio frequency band is intended for use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 273-300 (step 27) - the radio frequency band is intended for use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 300-308 (step 8) - the radio frequency band is intended for fixed and mobile services. Certain sections in this band are used by radio-electronic means of government communications, security and defense of the Russian Federation.
• 308-328.6 (step 20.6) - the radio frequency band is intended for primary use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 328.6-335.4 (step 6.8) - the radio frequency band is intended for the air radio navigation service and is primarily used by radio-electronic means of government communications, security and defense of the Russian Federation.
• 335.4-336 (step 0.6) - the radio frequency band is intended for primary use by radio-electronic means of government communications, security and defense of the Russian Federation.
• 336-344 (step 8) - the radio frequency band is intended for fixed and mobile services. Certain sections in this band are used by radio-electronic means of government communications, security and defense of the Russian Federation.
• 344-390 (step 46) - the radio frequency band is intended for primary use by radio-electronic means of government communications, security and defense of the Russian Federation.

Fire protection

All frequencies of the Moscow fire department headquarters:

• 148.050,
• 148.075,
• 148.125,
• 148.200.

Citizen Band

• 26.965-27.855 MHz (Europe),
• 26.960-27.850 MHz (Russia) - step 10 (NFM, AM, USB, LSB mode).
• 144-146 MHz - NFM USB CW DATA (for NFM step 25 kHz).
• 145.025, 145.125,145.625, 145.725 - repeater frequencies of the Moscow Radio Club.
• 146.100, 146.700 - amateur radio repeaters.
• 430-440 MHz - NFM USB CW DATA (for NFM step 25).

Some frequencies are occupied by trunk communication operators.

1260-1300 MHz (ham radio 23 cm band). 240-250 GHz (amateur radio 12 cm band). This is a European grid. For the Russian grid, accordingly, the last digit is “0”.

For example, 27.155MHz - C16E, 27.150MHz - C16R.

From useful channels(in relation to Moscow) - ЗсЭ, 9сЭ, 19сЭ, 21дE.

These are emergency channels, where dispatchers sit and report and receive messages about traffic jams and accidents. It is better to transmit information about road accidents and other emergency situations in the channels ZsE (Petrovka) or 9sE (Rescue Service).

Channel 9сE is dedicated to broadcasting traffic accidents and other emergency situations exclusively. If you register with the “Crik” service (Petrovka, ZSE) or with the Rescue Service (19сE, 21dE, registration is free, but mandatory), then you can ask the dispatcher to call and convey something or use it all as a pager (you can call control room and ask to transmit information to the person you need (of course, if he has a CB station).

The Polet-27 (9dE) service works similarly, only for free. And in other cases, just your own connection, going out of town, communication between cars, etc. There are channels occupied by some kind of interest clubs (to some extent this is “Flight-27”, since it is organized by the Association-27) and certain districts of Moscow.

The allowed channels (40 channels each in grids C and D) are pretty clogged, and additional grids are empty (A, B, E, F - if you really want to, you can work in them, everyone pretends that they don’t notice this violation)

VHF

Amateur VHF frequencies:

• 144-146 MHz - NFM USB CW DATA (for NFM step 25).
• 145.025, 145.625 inverse repeater (Dmitrov).
• 145.125, 144.525 repeater.
• 145,600, 145,000 repeater Serpukhov.
• 145.625, 145.025 repeater.
• 145.650, 145.050 repeater suspension at MSU.
• 145.700, 145.100 repeater Shchelkovo.
• 145.725, 145.125 repeater Troitsk.
• 145.750, 145.150 repeater Mitino.
• 430-440 MHz is the same, some of the frequencies are sold to trunk communication operators.

Note. As a rule, the reception and transmission frequencies of amateur radio repeaters (repeaters) differ from each other by 600 kHz. This parameter is also programmed by the manufacturer into the Kenwood TH-F7 transceiver.

Moreover, if the repeater’s receiving frequency is 145.750, then its transmission frequency will be -600 kHz, that is, 145.150 MHz. In inverse repeaters, everything is exactly the opposite.

The Kenwood TH-F7 transceiver also allows you to work with inverse repeaters; for this, the transceiver is reprogrammed from the keyboard so that the R indicator lights up on the display (see section 3.12).

Amateur radio satellite communications

Amateur radio satellite frequencies:

• 7000-7100 (step 100) - the radio frequency band is intended for amateur and amateur satellite services.
• 14000-142 50 (step 250) - the radio frequency band is intended for amateur and amateur satellite services.
• 21000-21450 (step 450) - the radio frequency band is intended for amateur and amateur satellite services.
• 28-29.7 MHz (step 1.7) - the radio frequency band is intended for amateur and amateur satellite services.
• 1240.000 - the beginning of the amateur radio 25-centimeter range (up to 1300.000).
• 1300.000 - the end of the amateur radio 25-centimeter range (from 1240.000).
• 2310.000 - the beginning of the amateur radio 12-centimeter range (up to 2450.000).
• 2450.000 - the end of the amateur radio 12-centimeter band (from 2310.000).

HF

Amateur HF frequencies:

• 1.83-1.93 MHz (160 m).
• 3.5-3.8 MHz (80 m).
• 7-7.1 MHz (40 m).
• 10.1-10.15 MHz (30m CW only).
• 14-14.35 MHz (20 m).
• 18.068-18.168 MHz (16 m).
• 21-21.45 MHz (15 m).
• 24.89-24.99 MHz (12 m).
• 28-29.7 MHz (10m).

When working with voice at frequencies below 10 MHz, LSB is used, above 10 MHz - USB. In AM, stations operate in the 160 and 10 m bands. Mainly used are CW, SSB and digital communications (Packet Radio, SSTV, RTTY). FM stations can rarely be heard on only 10 meters.

LOW BAND radio stations

LOW BAND radios are used by radio amateurs, security guards and various "outdoor" services.

• 30-36 MHz;
• 39-50 MHz;
• 36-42 MHz;
• 42-50 MHz;
• 136-162 MHz;
• 136-174 MHz;
• 146-174 MHz;
• 300-345 MHz;
• 403-433 MHz;
• 403-470 MHz;
• 438-470 MHz;
• 465-495 MHz;
• 490-520 MHz.

Some frequencies allocated for radiotelephones

For example, Panasonic cordless phones operate at frequencies of 31-40 MHz.

All frequencies are known ( full list is from the author of the book), on which all modern radiotelephones work. To adjust the transceiver receiver to the frequency of the base or handset of the telephone, you need to know the model of the radiotelephone used.

Air frequencies

Paging companies

In Moscow, paging companies operate+ in the range 146-168 and 450-475 MHz in NFM mode.

Closed paging systems can operate:

1. on subcarrier frequencies of radio stations and television;
2. in regular paging companies, but messages are encrypted during transmission;
3. at frequencies not typical for paging communications;
4. using transmission methods other than Pocsag.

Frequencies not owned by any well-known company: 160.5500, 164.3500, 474.5000.

Beeline cellular network (AMPS, DAMPS standard)

• 825-845 MHz -. mobile objects.
• 870-890 MHz - repeaters in NFM mode, step 30 (for AMPS, for D-AMPS - several channels per carrier).

MTS cellular network (Moscow Cellular Communications, NMT-450)

• 453-457.5 MHz - mobile objects.
• 463-467.5 MHz - repeaters.

MTS cellular network (Mobile Telesystems, GSM-900)

NFM mode, step 25. Frequencies:

• 890-915 MHz - mobile objects.
• 935-965 MHz - repeaters.

Digital communications, multiple channels per carrier

Cellular network GSM-1800 (Beeline).

Frequencies: 1.8-1.9 GHz digital communication, several channels per carrier.

Cellular network CDMA (no data).

Trunk networks

In Moscow there are a lot, mainly from 140 to 470 MHz (with exceptions) NFM mode, step 12.5 kHz.

Examples of frequencies (MHz):

• 150 (150.450)
• 373-375
• 435-452
• 433-434 (433.45, 433.475, etc.)
• 477-478 (477.60, 477.61, 477.625, 477.65, 477.675, 477.70, etc.)
• 484 (484.86)
• 864-870 perhaps, MTK-trunk.

RusAltai Network (ASVT)

• 337-343 MHz - mobile objects.
• 368-388 MHz - repeaters.

NFM mode, step 25.

AMT network

NFM mode, step 12.5 or 25. Duplex and half-duplex. Frequencies:

transmission/reception

• 300-308 MHz/336-344 MHz,
• 336-340 MHz/346-350 MHz.

INMARSAT satellite network

• 1626.5-1646.5 uplink from terminal stations.
• 1530-1545 downward beam to terminal stations.

Other frequencies that are active on the air

• 30-50 MHz (Low band);
• 34.150 Moslift;
• 34.200 Mosvodoprovod;
• 34.875 Salute;
• 36.050 Regional water supply;
• 36.075 Instrumentation and control;
• 36.325 Sewerage;
• 36.925 Moslift;
• 38.750, 39.800, 42.870, 44.350, 44.600 Military;
• 40.100, 44.800 Regional firefighters;
• 41.700 Autobeeper;
• 41,800 Regional doctors 41,900 DEZ;
• 41.950 Depot;
• 42.150 Moskanalizatsiya;
• 42.250 Forestry;
• 43.125, 43.825 Reserve channels in case of war;
• 43.200 Mosenergo;
• 43.800, 44.750 Taxi;
• 46.200, 43.975, 44.500 armored personnel carriers;
• 45.950 Mosga.

Frequencies of some service radio stations in St. Petersburg, and not only

List of frequencies permanently prohibited in Russia

495-505 kHz(step 10) - radio frequency 500 kHz is international distress and calling frequency for Morse radiotelegraphy.

Any emissions that may cause harmful interference to communications in case of distress, accident, emergency or for safety purposes are prohibited on the following frequencies:

• 500 kHz,
• 2174.5 kHz,
• 2182 kHz,
• 2187.5 kHz,
• 4125 kHz,
• 4177.5 kHz,
• 4207.5 kHz,
• 6215 kHz,
• 6268 kHz,
• 6312 kHz,
• 8291 kHz,
• 8376.5 kHz,
• 8414.5 kHz,
• 12290 kHz,
• 12520 kHz,
• 12577 kHz,
• 16420 kHz,
• 16695 kHz,
• 16804.5 kHz,
• 121.5 MHz,
• 156.525 MHz,
• 156.8 MHz
• and in the frequency bands 406-406.1 MHz, 1544-1545 MHz and 1645.5-1646.5 MHz.

Any emissions on any other discrete frequency that cause harmful interference to disaster and safety communications are also prohibited.

2173.5-2190.5 (step 17) - the radio frequency 2182 kHz (carrier) is the calling frequency for radiotelephony.

This radio frequency can be used for search and rescue purposes for manned spacecraft. Radio frequencies 2174.5 kHz, 4177.5 kHz, 6268 kHz, 8376.5 kHz, 12520 kHz and 16695 kHz are international frequencies intended exclusively for the exchange of information in the event of distress and for ensuring safety at sea using narrowband telegraphy (printing) equipment.

Radio frequencies 2187.5 kHz, 4207.5 kHz, 6312 kHz, 8114.5 kHz, 12577 kHz and 16804.5 kHz are international frequencies intended exclusively for distress and navigation safety calls using digital selective calling equipment. Other transmissions in the specified frequency band are prohibited.

117.975-137 (step 19.025) - the radio frequency band is intended for preferential use aeronautical mobile service. Portions of this radio frequency band may be used by the aeronautical mobile-satellite (R) service.

Airborne emergency radio frequency 121.5 MHz used by stations of the aeronautical mobile service operating in the frequency band 117.975-137 MHz for radiotelephone communication in case of disaster and to ensure safety.

121.5 MHz can also be used for these purposes by stations life-saving equipment and emergency radio beacons-indicators disaster sites, for the purpose of search and rescue of manned spacecraft. 121.45-121.55 MHz can be used by the mobile satellite service to receive signals on board the satellite from emergency radio beacons transmitting signals on the radio frequency 121.5 MHz.

123.1 MHz is the auxiliary frequency for air emergency frequency 121.5 MG tz and is intended for use by stations of the aeronautical mobile service, as well as other mobile and land stations participating in joint search and rescue operations.

Mobile stations in the maritime mobile service may communicate on these frequencies with stations in the aeronautical mobile service in case of distress and for safety purposes.

136-137 MHz can be used Space Operations Service(Space-to-Earth), space research service (Space-to-Earth) and meteorological satellite (Space-to-Earth) service on a secondary basis.

156.8 MHz is international distress frequency, security and calling in the maritime mobile service for radiotelephony. This radio frequency can be used to search and rescue manned spacecraft.

406-406.1 (step 0.1) - the radio frequency band is intended exclusively for satellite emergency beacons- disaster location indicators (Earth-Space).

List of frequencies prohibited for radio communications

• 500 kHz 40,000
• 1.544-1.545 MHz (hereinafter MHz) 40.100
• 1,645-1,646 40,200
• 2,040 40,500
• 2125-2135 41,800
• 2,145 42,000
• 2,147-2,153 42,450
• 2,173-2,190 42,750
• 2,380 43,150
• 2,498-2,502 43,750
• 2,850-3,155 44,300
• 3,400-3,500 44,400
• 3.900-3,950 44,600
• 4,125 44,700 4,175 44,800 4,177 44,900 4,188 45,100 4,207 45,125 4,210 45,200 4,430 45,300 4,650-4,750 45,350
• 4.995-5,005 45,400 5,410 45,600 5,480-5,730 45,700 6,215 45,800 6,268 46,425 6,282 46,475 6,312 46,550 6,314 46,600 6,525-6,765 46,650 8,195-8,416 46,700 8,815-9,040 46,775
• 9.995-10,100 46,825
• 11,175-11,400 46,875 12,230-12,575 46,956 13,200-13,360 47,075 14,957-14,967 47,125
• 14.990-15,900 47,375 16,360-16,800 47,575
• 17.900-18,030 47,825 18,055-18,065 47,975 18,780-18,900 48,075 19,680 74,600-75,400
• 19.990-20,010 121,500
• 21,850-21,870 121,716-121,784 21,924-22,000 130,133-130,201 22,376 139,174-139,242
• 24.990-25,010 156,525
• 26,100 156,800 33,825 243,000 36,650 300,20.

Literature: Kashkarov A.P. Electronic devices for coziness and comfort.

In contact with

Classmates

Permitted VHF frequencies for radio amateurs and their purpose

I often receive questions from radio amateurs regarding the assignment of frequencies on the VHF band. The fact is that the number of frequencies is limited and some of them are reserved for certain types of connections. Also, some frequencies are allocated for the needs of creating repeaters. For this reason, novice radio amateurs are afraid to occupy a specialized frequency and get hit in the ears. To avoid having to answer these questions often, I will provide a table for the VHF range.

The range from 144 to 146 MHz is allocated to the amateur radio service on a primary basis. Radio amateurs of the fourth category have the right to operate on these frequencies with a power of 5 W, the second and third at 10 W, and the first category with 50 W (for EME and MC communications of the first category it is allowed to use up to 500 W).

It turns out that for direct communication in frequency modulation, frequencies from 145.206 MHz to 145.594 MHz are allocated. Grid step 12.5 kHz. This table was compiled in accordance with the decision of the SCRF dated July 22, 2014 No. 10-07-01.

Radio bands and frequencies

In this article we will briefly look at what frequencies are allocated for radio communications and what radio stations and what range should be considered when choosing equipment in a given case. The article is presented in free form, using simplifications in some concepts and details. Does not claim encyclopedic accuracy, but will give a general idea of ​​the frequencies used in Russia and the radio communication equipment used.

Let's consider What ranges do radios operate in? and why, in one case or another, different ones are used radio frequency ranges.

Shortwave range - 1-30 MHz

HF radio It is used primarily by the military, the Ministry of Emergency Situations, the navy, forestry and environmental organizations for professional communications over long distances - from 150 to 8000 km.

The main disadvantages of the HF range are low noise immunity and the need to use large antennas up to several tens of meters long. Pros: absolute autonomy, long communication range and low cost compared to satellite communications.

Main equipment used: Icom, IC-M802., Vertex VX-1700, VX-1400, VX-1200/1210., Kenwood TK-90, Cordon P-12, Q-Mac HF 90M, Barrett PRC-2090, PRC- 2091, Karat, Angara.

Also, within the range of 1-30 MHz, there are 9 frequency sections allocated for communication to radio amateurs. The main HF amateur radio equipment used is transceivers from Kenwood, Icom, Yaesu, and Elecraft. If for professional stable radio communication the range is usually limited to 8000 km, then radio amateurs often conduct transcontinental radio communication sessions with their colleagues located on the other side of the globe.

Currently, the market for software-based radio - SDR equipment - is gaining momentum. Software-based radio is beginning to be widely used in amateur radio, military, and commercial applications. To date, Harris and Alcatel Lucent have already implemented several successful projects that use equipment based on SDR technology and cognitive radio (a radio system capable of receiving information about the characteristics of its own operation and adjusting its operating parameters based on this data). In the future, SDR technology has every chance of becoming a new standard in the telecommunications market.

Civil band - 27 MHz

Conventionally called the “27 MHz band”. Frequency range 25.6-30.1 MHz (officially permitted section - 26.965-27.860 MHz). Another name is CB range from the English abbreviation CB - Citizen Band.

Range of truckers on walkie-talkie This is the 15th channel, with a frequency of 27.135 MHz, in amplitude modulation (AM) mode. The channel is actively used by truckers for communication on the highways. In big cities, CB radios 27 MHz, used by motorists to exchange information about traffic conditions. In different cities, different channels are used for urban communication. For example, in Krasnoyarsk it is channel 40, with a frequency of 27.405 MHz, in Kemerovo it is channel 27, with a frequency of 27.275 MHz. Frequency modulation (FM) is used at the frequencies of city auto channels.

Also, radio stations in this range are used by small taxi companies and cargo carriers, rapid response teams of security companies and utility services. Despite the affordability of the equipment, and the fact that, according to Decree of the Government of the Russian Federation dated October 13, 2011 No. 837, 27 MHz radios are not subject to registration, it is necessary to take into account the fact that the civil range is subject to large atmospheric and industrial interference and the use walkie-talkiesCB band for commercial purposes it is not suitable for enterprises that require high-quality radio communications. Portable CB radios, due to their small radius of action and relatively large dimensions, they are not particularly widespread and are used mainly during loading and unloading operations or at truck stops.

Most of the CB radio stations available in Russia are presented in our online store.

Buy CB radios which you can find in our online store are presented in .

Low-Band range - 33-57.5 MHz

This is the lower part of the VHF mobile radio range.

Due to the large influence of industrial interference in cities and interference from TV broadcast transmitters, this range is used mainly in rural areas. The main users, since the times of the USSR, are ambulance stations and agricultural enterprises. Today, most of the world's manufacturers have stopped producing radio stations for these frequencies. Equipment for the Low-Band range is currently offered by domestic manufacturers - the companies Granit and Webr. In warehouses you can still find radio stations from famous brands: Motorola GP340, GM360., Vertex Standard VX-3000L. The only available foreign manufacturer of equipment in the 33-57.5 MHz range remains Alinco, Inc. The company offers the DJ-V17L wearable radio and the DR-135LH and DR-M06R car (base) radios.

Aviation band - 118-137 MHz

Aircraft communicate with each other and with ground services in this frequency range. Unlike most other types of VHF communications, amplitude modulation is used. Popular airborne equipment –

wearable aviation radios:

156.8375-174 MHz - mobile and fixed terrestrial communications.

In accordance with the Basic Law “On Communications” dated July 7, 2003 No. 126-FZ, in order to organize radio communications in this range, it is necessary to obtain permission from the Federal State Unitary Enterprise “GRChTs”. If it is necessary to obtain frequencies, we can provide consulting and support in obtaining permits.

High noise immunity and good signal transmission have made the 136-174 MHz range the most popular among users and equipment manufacturers. Our store offers most popular models of VHF radios and antennas. Walkie-TalkieVHF band in our store are presented in .

River band - 300 MHz

Used for communications on inland waterways.

Operating frequencies of walkie-talkies are in the range 300.0125-300.5125 MHz and 336.0125-336.5125 MHz.

River band radio comes with pre-installed channels dedicated to communication with ships and coastal services for various purposes.

Channel radio frequencies– their numbers and purpose are established by the “Instructions for the organization of ship radio communications in the basin (region)”, approved by the River Fleet Service of the Ministry of Transport Russian Federation and agreed with local authorities of the State Supervision of Radio Communications. So, the main channels are:

Channel 2 (300.05 MHz) - for communication between ships;

Channel 3 (300.1 MHz) - for communication with gateway dispatchers;

Channel 4 (300.15 MHz) - for communication with other river fleet services;

Channel 5 (300.2 MHz) - for calling ships, coordinating the order of passing and overtaking when maneuvering and transmitting distress signals.

Channels 25 and 43 (336.2 MHz and 300.125 MHz) are generally accepted for communication between yachts.

All radio stations installed on ships and on inland waterways must have an Approval from the River Register of Russia (RRR) and a Certificate from the Ministry of Communications, regardless of their affiliation and whether these radio stations are the main or additional equipment.

According to the frequency allocation approved by the International Telecommunication Union (ITU), frequencies in the range 156-162 MHz are used throughout the world for communications between ships (river and sea). The river band of 300 MHz is used only in Russia and the choice of equipment offered for this range is small. Popular river radio stations: Radioma-300, Vertex Standard VX-451/VX-454, .

VHF range - 400-470 MHz

In foreign sources, the range is designated as UHF, the name of which is derived from the capital letters Ultra High Frequency.

The propagation features of UHF frequencies make it possible to recommend this range for use in dense urban areas and in the mountains. In forest conditions, radio stations at 400 MHz are inferior to radio stations in the 136-174 MHz range.

Frequency bands are allocated in the range for professional use, for radio amateurs and for license-free use by everyone.

Walkie-talkie frequencies, the operation of which, in accordance with the Basic Law “On Communications” dated July 7, 2003 No. 126-FZ, is possible only with permits:

420-430 MHz - mobile and fixed terrestrial communications;

430-440 MHz - amateur radio band;

440-470 MHz - mobile and fixed terrestrial communications.

If it is necessary to obtain frequency ratings, we can provide consulting and support in obtaining permits.

Areas of the range that, according to Decree of the Government of the Russian Federation of December 31, 2004 No. 896, do not require permits - permitted range of radios(license-free frequencies):

433.075-434.775 MHz – LPD (“Low Power Device”) range. Standard frequency grid of 69 nominal values, with a step of 25 kHz;

Just a short time ago, mostly home-made equipment was used to operate in the 144-145 MHz range. VHF transverters were popular among radio amateurs, many of which were comparable in size to the transceiver used with it. Radio amateurs converted decommissioned industrial VHF radio stations of the Palma type to the amateur VHF 145 MHz band, obtaining a radio station operating on several channels. Then “Viols”, and later “Mayaks”, operating on forty channels, became available to radio amateurs. These radio stations then looked simply fantastic in their capabilities!

Currently, you can relatively inexpensively purchase multi-channel portable VHF transceivers from world-famous companies - “YAESU”, “KENWOOD”, “ALINCO”, which in terms of their parameters and ease of operation are significantly superior to both home-made equipment in the 145 MHz range and converted industrial equipment - “Palms” ", "Beacons", "Violas".

But to work through a repeater from home, office, while driving or working from a car, you need an antenna that is more effective than the one used in conjunction with a portable “rubber band” radio station. When using a stationary "branded" VHF station, it is often advisable to use a homemade VHF antenna with it, since a decent "branded" outdoor antenna The 145 MHz band is not cheap.

This material is dedicated to the production of simple homemade antennas suitable for use with stationary and portable VHF radio stations.

Features of 145 MHz antennas

Due to the fact that for the manufacture of antennas in the 145 MHz range, thick wire is usually used - with a diameter of 1 to 10 mm (sometimes thicker vibrators are used, especially in commercial antennas), antennas in the 145 MHz range are broadband. This often allows you to design the antenna exactly according to specified sizes do without her additional settings on the 145 MHz band.

To tune antennas in the 145 MHz range, you must have an SWR meter. This can be either a homemade device or an industrial one. On the 145 MHz band, radio amateurs practically do not use bridge antenna resistance meters, due to the apparent complexity of their correct manufacture. Although, with careful manufacturing of the bridge meter and, therefore, its correct operation on this range, it is possible to accurately determine the input impedance of VHF antennas. But even using only a pass-through SWR meter, it is quite possible to tune homemade VHF antennas. The power of 0.5 W, which is provided by imported portable radio stations in the “LOW” mode and domestic portable VHF radio stations such as “Dnepr”, “Viola”, “VEBR”, is quite enough to operate many types of SWR meters. The “LOW” mode allows you to tune antennas without fear of failure of the output stage of the radio station at any input impedance of the antenna.

Before you start tuning the VHF antenna, it is advisable to make sure that the SWR meter readings are correct. It is a good idea to have two SWR meters designed to operate in 50 and 75 Ohm transmission paths. When setting up VHF antennas, it is advisable to have a control antenna, which can be either a “rubber band” from a portable radio station or a homemade quarter-wave pin. When tuning an antenna, the level of field strength created by the tuned antenna is measured relative to the control one. This makes it possible to judge the comparative efficiency of the tuned antenna. Of course, if you use a standard calibrated field strength meter for measurements, you can get an accurate estimate of the antenna's performance. When using a calibrated field meter, it is easy to measure the antenna radiation pattern. But even using homemade field strength meters during measurements and having obtained only a qualitative picture of the distribution of electromagnetic field strength, one can fully draw a conclusion about the efficiency of the tuned antenna and approximately estimate its radiation pattern. Let's consider practical designs of VHF antennas.

Simple antennas

The simplest outdoor VHF antenna (Fig. 1) can be made using an antenna operating in conjunction with a portable radio station. On the window frame, from the outside (Fig. 2) or from the inside, a metal corner is attached to an extension wooden block, in the center of which there is a socket for connecting this antenna. It is necessary to strive to ensure that the coaxial cable leading to the antenna is of the minimum required length. 4 counterweights, each 50 cm long, are attached to the edges of the corner. It is necessary to ensure good electrical contact between the counterweights and the antenna connector with the metal corner. The radio's shortened twisted antenna has an input impedance of 30-40 ohms, so a coaxial cable with a characteristic impedance of 50 ohms can be used to power it. Using the angle of inclination of the counterweights, you can change the input impedance of the antenna within certain limits, and, therefore, match the antenna with the coaxial cable. Instead of the branded “elastic band,” you can temporarily use an antenna made of copper wire with a diameter of 1-2 mm and a length of 48 cm, which is inserted into the antenna socket with its sharpened end.

Figure 1. Simple outdoor VHF antenna

Figure 2. Design of a simple outdoor VHF antenna

A VHF antenna made of coaxial cable with the outer braid removed works reliably. The cable is embedded in an RF connector similar to the connector of a “proprietary” antenna (Fig. 3). The length of the coaxial cable used to make the antenna is 48 cm. This antenna can be used in conjunction with a portable radio station to replace a broken or lost standard antenna.

Figure 3. Simple homemade VHF antenna

To quickly manufacture an external VHF antenna, you can use a connecting coaxial cable 2-3 meters long, which is terminated with connectors corresponding to the antenna socket of the radio station and antenna. The antenna can be connected to such a piece of cable using a high-frequency tee (Fig. 4). In this case, a rubber band antenna is connected from one end of the tee, and counterweights 50 cm long are screwed on from the other end of the tee, or another type of radio ground for the VHF antenna is connected through the connector.

Figure 4. Simple remote VHF antenna

Homemade antennas portable radio

If the standard antenna of a portable radio station is lost or broken, you can make a homemade twisted VHF antenna. To do this, use a base - polyethylene insulation of a coaxial cable with a diameter of 7-12 mm and a length of 10-15 cm, on which initially 50 cm of copper wire with a diameter of 1-1.5 mm is wound. To tune a twisted antenna, it is very convenient to use a frequency response meter, but you can also use an ordinary SWR meter. Initially, the resonant frequency of the assembled antenna is determined, then, by biting off part of the turns, shifting, pushing apart the turns of the antenna, the twisted antenna is tuned to resonance at 145 MHz.

This procedure is not very complicated, and by setting up 2-3 twisted antennas, a radio amateur can configure new twisted antennas in literally 5-10 minutes, of course, if the above-mentioned devices are available. After setting up the antenna, it is necessary to fix the turns either with electrical tape, or with a cambric soaked in acetone, or with a heat-shrinkable tube. After fixing the turns, it is necessary to once again check the frequency of the antenna and, if necessary, adjust it using the upper turns.

It should be noted that in “branded” shortened twisted antennas, heat-shrinkable tubes are used to fix the antenna conductor.

Half-wave field antenna

For efficient work For quarter-wave antennas, multiple quarter-wave counterweights must be used. This complicates the design for a quarter-wave field antenna, which must be located in space relative to the VHF transceiver. In this case, you can use a VHF antenna with an electrical length of L/2, which does not require counterweights for its operation, and provides a directivity pattern pressed to the ground and ease of installation. For an antenna with an electrical length of L/2, the problem is to match its high input impedance with the low characteristic impedance of the coaxial cable. An antenna with a length of L/2 and a diameter of 1 mm will have an input impedance on the 145 MHz band of about 1000 Ohms. Matching using a quarter-wave resonator, which is optimal in this case, is not always convenient in practice, since it requires selecting the connection points of the coaxial cable to the resonator for its effective operation and fine-tuning the antenna pin to resonance. The resonator dimensions for the 145 MHz range are also relatively large. Destabilizing factors on the antenna when it is matched using a resonator will be especially pronounced.

However, with low powers supplied to the antenna, quite satisfactory matching can be achieved using a P-circuit, similar to what is described in the literature. The diagram of a half-wave antenna and its matching device is shown in Fig. 5. The length of the antenna pin is selected slightly shorter or longer than the L/2 length. This is necessary because even with a slight difference in the electrical length of the antenna from L/2, the active resistance of the antenna impedance decreases noticeably, and its reactive part by initial stage increases slightly. As a result, it is possible to match such a shortened antenna using the P-circuit with greater efficiency than matching an antenna with a length of exactly L/2. It is preferable to use an antenna with a length slightly longer than L/2.

Figure 5. VHF antenna matching using a P-circuit

The matching device used air tuning capacitors of the KPVM-1 type. Coil L1 contains 5 turns of silver-plated wire with a diameter of 1 mm, wound on a mandrel with a diameter of 6 mm and a pitch of 2 mm.

Setting up the antenna is not difficult. By including an SWR meter in the antenna cable path and at the same time measuring the level of field strength created by the antenna by changing the capacitance of variable capacitors C1 and C2, compressing and stretching the turns of coil L1, we achieve the minimum readings of the SWR meter and, accordingly, the maximum readings of the field strength meter. If these two maximums do not coincide, you need to slightly change the length of the antenna and repeat its adjustment again.

The matching device was placed in a housing soldered from foil fiberglass with dimensions of 50*30*20 mm. When working from a stationary workstation of a radio amateur, the antenna can be placed in the window opening. When working in the field, the antenna can be suspended by its upper end from a tree using a fishing line, as shown in Fig. 6. A 50 ohm coaxial cable can be used to power the antenna. Using a 75-ohm coaxial cable will slightly increase the efficiency of the antenna matching device, but at the same time will require configuring the radio output stage to operate at a 75-ohm load.

Figure 6. Antenna installation for field use

Foil based window antennas

Based on adhesive foil used in security alarm systems, very simple designs of window VHF antennas can be built. This foil can be purchased with an adhesive base. Then, having freed one side of the foil from the protective layer, you simply press it against the glass and the foil instantly sticks securely. Foil without an adhesive base can be glued to the glass using varnish or Moment type glue. But for this you need to have some skill. The foil can even be secured to the window using adhesive tape.

With appropriate training, it is quite possible to make a high-quality soldered connection between the central core and braid of a coaxial cable with aluminum foil. Based on personal experience, each type of such foil requires its own flux for soldering. Some types of foil can be soldered well even using only rosin, some can be soldered using soldering oil, other types of foil require the use of active fluxes. The flux must be tested on the specific type of foil used to make the antenna in advance of installation.

Good results are obtained by using a foil fiberglass substrate for soldering and attaching the foil, as shown in Fig. 7. A piece of foil fiberglass laminate is glued to the glass using Moment glue, the antenna foil is soldered to the edges of the foil, the cores of the coaxial cable are soldered to the copper foil of the fiberglass laminate at a short distance from the foil. After soldering, the connection must be protected with moisture-resistant varnish or glue. Otherwise, corrosion of this connection may occur.

Figure 7. Connecting the antenna foil to the coaxial cable

Let's analyze the practical designs of window antennas built on the basis of foil.

Vertical window dipole antenna

The diagram of a vertical dipole window VHF antenna based on foil is shown in Fig. 8.

Figure 8. Windowed vertical dipole VHF antenna

The quarter-wave pole and counterweight are positioned at an angle of 135 degrees to keep the antenna system's input impedance close to 50 ohms. This makes it possible to use a coaxial cable with a wave impedance of 50 Ohms to power the antenna and use the antenna in conjunction with portable radio stations, the output stage of which has such an input impedance. The coaxial cable should run perpendicular to the antenna along the glass for as long as possible.

Foil Based Window Loop Antenna

The frame window VHF antenna shown in Fig. will work more efficiently than a dipole vertical antenna. 9. When feeding the antenna from a side angle, the maximum radiated polarization is located in the vertical plane; when feeding the antenna in the bottom angle, the maximum radiated polarization is in the horizontal plane. But at any position of the feed points, the antenna emits a radio wave with combined polarization, both vertical and horizontal. This circumstance is very favorable for communication with portable and mobile radio stations, the position of the antennas of which will change while moving.

Figure 9. Frame window VHF antenna

The input impedance of the window loop antenna is 110 ohms. To match this resistance with a coaxial cable with a characteristic impedance of 50 Ohms, a quarter-wave section of coaxial cable with a characteristic impedance of 75 Ohms is used. The cable should run perpendicular to the antenna axis for as long as possible. Loop antenna has a gain approximately 2 dB higher relative to a dipole window antenna.

When made from foil window antennas with a width of 6-20 mm, they do not require tuning and operate in a frequency range much wider than the amateur band of 145 MHz. If the resulting resonant frequency of the antennas turns out to be lower than the required one, then the dipole can be adjusted by symmetrically cutting off the foil from its ends. The loop antenna can be configured using a jumper made from the same foil that was used to make the antenna. The foil closes the antenna sheet in the corner, opposite the power points. Once configured, contact between the jumper and the antenna can be achieved either by soldering or using adhesive tape. Such adhesive tape should press the jumper firmly enough to the antenna surface in order to ensure reliable electrical contact with it.

Significant power levels can be supplied to antennas made of foil - up to 100 watts or more.

Outdoor vertical antenna

When placing an antenna outside a room, the question always arises of protecting the opening of the coaxial cable from atmospheric influences, using a high-quality antenna support insulator, moisture-resistant wire for antennas, etc. These problems can be solved by making a protected outdoor VHF antenna. The design of such an antenna is shown in Fig. 10.

Figure 10. Protected outdoor VHF antenna

A hole is made in the center of a 1 meter long plastic water pipe into which a coaxial cable can fit tightly. Then the cable is threaded there, protruded from the pipe, exposed at a distance of 48 cm, the cable screen is twisted and soldered at a length of 48 cm. The cable with the antenna is inserted back into the pipe. Standard plugs are placed on the top and bottom of the pipe. Moisture-proofing the hole where the coaxial cable enters is not difficult. This can be done using automotive silicone sealant or fast-curing automotive epoxy. The result is a beautiful, moisture-proof, protected antenna that can operate under the influence of weather conditions for many years.

To fix the vibrator and antenna counterweight inside, you can use 1-2 cardboard or plastic washers, tightly placed on the antenna vibrators. The pipe with the antenna can be installed on a window frame, on a non-metallic mast, or placed in another convenient place.

Simple coaxial collinear antenna

A simple collinear coaxial VHF antenna can be made from coaxial cable. To protect this antenna from atmospheric influences, a piece of water pipe can be used, as described in the previous paragraph. The design of a collinear coaxial VHF antenna is shown in Fig. eleven.

Figure 11. Simple collinear VHF antenna

The antenna provides a theoretical gain of at least 3 dB greater than a quarter-wave vertical. It does not require counterweights for its operation (although their presence improves the performance of the antenna) and provides a directivity pattern close to the horizon. A description of such an antenna has repeatedly appeared on the pages of domestic and foreign amateur radio literature, but the most successful description was presented in the literature.

Antenna dimensions in Fig. 11 are indicated in centimeters for a coaxial cable with a shortening factor of 0.66. Most coaxial cables with polyethylene insulation have this shortening factor. The dimensions of the matching loop are shown in Fig. 12. Without the use of this loop, the SWR of the antenna system may exceed 1.7. If the antenna is tuned below the 145 MHz range, it is necessary to shorten the upper section slightly, if higher, then lengthen it. Certainly, optimal setting possible by proportional shortening and lengthening of all parts of the antenna, but this is difficult to do in amateur radio conditions.

Figure 12. Dimensions of the matching loop

Despite the large size of the plastic pipe required to protect this antenna from atmospheric influences, the use of a collinear antenna of this design is quite advisable. The antenna can be moved away from the building using wooden slats, as shown in Fig. 13. The antenna can withstand significant power supplied to it, up to 100 watts or more, and can be used in conjunction with both stationary and portable VHF radio stations. Using such an antenna in conjunction with low-power portable radio stations will give the greatest effect.

Figure 13. Collinear Antenna Installation

Simple collinear antenna

This antenna was assembled by me similar to the design of a car remote antenna used in a cellular radiotelephone. To convert it to the 145 MHz amateur band, I proportionally changed all the dimensions of the “telephone” antenna. The result was an antenna, the diagram of which is shown in Fig. 14. The antenna provides a horizontal radiation pattern and a theoretical gain of at least 2 dB over a simple quarter-wave pin. A coaxial cable with a characteristic impedance of 50 Ohms was used to power the antenna.

Figure 14. Simple collinear antenna

A practical antenna design is shown in Fig. 15. The antenna was made of a whole piece of copper wire with a diameter of 1 mm. Coil L1 contained 1 meter of this wire, wound on a mandrel with a diameter of 18 mm, the distance between the turns was 3 mm. When the design is made exactly to size, the antenna requires virtually no adjustment. It may be necessary to slightly adjust the antenna by compressing and stretching the coil turns to achieve a minimum SWR. The antenna was placed in a plastic water pipe. Inside the pipe, the antenna wire was fixed using pieces of foam plastic. Four quarter-wave counterweights were installed at the lower end of the pipe. They were threaded and secured to a plastic pipe using nuts. Counterweights can be 2-4 mm in diameter, depending on the ability to thread them. For their manufacture, you can use copper, brass, or bronze wire.

Figure 15. Design of a simple collinear antenna

The antenna can be installed on wooden slats on the balcony (as shown in Fig. 13). This antenna can withstand significant levels of power applied to it.

This antenna can be considered as a shortened HF antenna with a central extension coil. Indeed, the antenna resonance measured using a bridge resistance meter in the HF range turned out to lie in the frequency region of 27.5 MHz. Obviously, by varying the diameter of the coil and its length, but maintaining the length of the winding wire, you can ensure that the antenna operates both in the VHF range of 145 MHz and in one of the HF bands - 12 or 10 meters. To operate on the HF bands, it is necessary to connect four counterweights with a length of L/4 for the selected HF band to the antenna. This dual use of the antenna will make it even more versatile.

Experimental 5/8 wave antenna

When conducting experiments with radio stations in the 145 MHz range, it is often necessary to connect the antenna under test to its output stage in order to check the operation of the radio station’s receiving path or to adjust the transmitter output stage. For these purposes, I have been using a simple 5/8 wave VHF antenna for a long time, the description of which was given in the literature.

This antenna consists of a section of copper wire with a diameter of 3 mm, which is connected at one end to an extension coil and the other to a tuning section. A thread is cut at the end of the wire connected to the coil, and at the other end a tuning section made of copper wire with a diameter of 1 mm is soldered. The antenna is matched with a coaxial cable with a characteristic impedance of 50 or 75 Ohms by connecting to different turns of the coil, and the tuning section can be slightly shortened. The antenna diagram is shown in Fig. 16. The antenna design is shown in Fig. 17.

Figure 16. Diagram of a simple 5/8 wave VHF antenna

Figure 17. Design of a simple 5/8 wave VHF antenna

The coil is made on a plexiglass cylinder with a diameter of 19 mm and a length of 95 mm. At the ends of the cylinder there is a thread into which the antenna vibrator is screwed on one side, and on the other side it is screwed to a piece of foil fiberglass measuring 20*30 cm, which serves as the “ground” of the antenna. A magnet from an old speaker was glued to the back of it, as a result of which the antenna can be attached to a windowsill, to a heating radiator, or to other iron objects.

The coil contains 10.5 turns of wire with a diameter of 1 mm. The coil wire is evenly distributed throughout the frame. The outlet to the coaxial cable is made from the fourth turn from the grounded end. The antenna vibrator is screwed into the coil, a contact lamella is inserted under it, to which the “hot” end of the extension coil is soldered. The lower end of the coil is soldered to the antenna ground foil. The antenna provides SWR in the cable no worse than 1:1.3. Tuning the antenna is carried out by shortening its upper part with pliers, which is initially made slightly longer than necessary.

I conducted experiments on installing this antenna on window glass. In this case, a vibrator initially 125 centimeters long made of aluminum foil was glued to the center of the window. The same extension coil was used and was installed on the window frame. The counterweights were made of foil. The ends of the antenna and counterweights were bent slightly to fit on the window glass. A view of a 5/8 window - wave VHF antenna is shown in Fig. 18. The antenna is easily tuned to resonance by gradually shortening the vibrator foil using a blade, and gradually switching the coil turns to a minimum SWR. The window antenna does not spoil the interior of the room and can be used as a permanent antenna for operating on the 145 MHz band from home or office.

Figure 18. Window 5/8 - wave VHF antenna

Efficient portable radio antenna

In cases where communication using a standard rubber band is not possible, a half-wave antenna can be used. It does not require “ground” for its operation and when working over long distances it provides a gain of up to 10 dB compared to a standard “rubber band”. These are quite realistic figures, considering that the physical length of a half-wave antenna is almost 10 times longer than the rubber band.

The half-wave antenna is powered by voltage and has a high input impedance that can reach 1000 Ohms. Therefore, this antenna requires a matching device when used in conjunction with a radio station having a 50 ohm output. One of the options for a matching device based on a P-circuit has already been described in this chapter. Therefore, for variety, for this antenna we will consider using another matching device made on a parallel circuit. In terms of their operating efficiency, these matching devices are approximately equal. The diagram of a half-wave VHF antenna together with a matching device on a parallel circuit is shown in Fig. 19.

Figure 19. Half-wave VHF antenna with matching device

The circuit coil contains 5 turns of silver-plated copper wire with a diameter of 0.8 mm, wound on a mandrel with a diameter of 7 mm along a length of 8 mm. Setting up the matching device consists of tuning the circuit L1C1 into resonance using the variable capacitor C1, and using the variable capacitor C2 to regulate the connection of the circuit with the output of the transmitter. Initially, the capacitor is connected to the third turn of the coil from its grounded end. Variable capacitors C1 and C2 must be with an air dielectric.

For the antenna vibrator, it is advisable to use a telescopic antenna. This will make it possible to carry the half-wave antenna in a compact folded state. This also makes it easier to configure the antenna together with a real transceiver. At initial setup antenna, its length is 100 cm. During the setup process, this length can be slightly adjusted according to better work antennas. It is advisable to make appropriate marks on the antenna so that you can subsequently install the antenna directly to the resonant length from its folded position. The box where the matching device is located must be made of plastic in order to reduce the capacitance of the coil to “ground”; it can be made of foil fiberglass. This depends on the actual operating conditions of the antenna.

The antenna is tuned using the field strength indicator. Using an SWR meter, tuning an antenna is advisable only if it is not operated on the radio body, but when an extension coaxial cable is used in conjunction with it.

When operating the antenna twice on the radio body and using an extension coaxial cable, two marks are made on the antenna pin, one corresponding to the maximum field strength level when operating the antenna on the radio body, and the other mark corresponds to the minimum SWR when using an extension coaxial cable with the antenna. Usually these two marks are slightly different.

Vertical continuous antennas with gamma matching

Vertical antennas made from a single vibrator are wind-resistant, easy to install, and take up little space. To perform them, you can use copper tubes, aluminum power electrical wire with a diameter of 6-20 mm. These antennas can be quite easily matched with a coaxial cable with a characteristic impedance of both 50 and 75 Ohms.

Very simple to implement and easy to configure is a continuous half-wave VHF antenna, the design of which is shown in Fig. 20. Gamma matching is used to power it through a coaxial cable. The material from which the antenna vibrator and gamma matching are made must be the same, for example, copper or aluminum. Due to the mutual electrochemical corrosion of many pairs of materials, it is unacceptable to use different metals to perform the antenna and gamma matching.

Figure 20. Continuous half-wave VHF antenna

If a bare copper tube is used to make the antenna, then it is advisable to adjust the gamma matching of the antenna using a shorting jumper as shown in Fig. 21. In this case, the surface of the pin and the gamma matching conductor is carefully cleaned and using a bare wire clamp as shown in Fig. 21a achieve a minimum SWR in the coaxial antenna power cable. Then, at this point, the gamma matching wire is slightly flattened, drilled and connected with a screw to the antenna surface, as shown in Fig. 21b. It is also possible to use soldering.

Figure 21. Setting up gamma matching of a copper antenna

If an aluminum wire from a power electrical cable in plastic insulation is used for the antenna, then it is advisable to leave this insulation to prevent corrosion of the aluminum wire by acid rain, which is inevitable in urban environments. In this case, the gamma matching of the antenna is adjusted using a variable capacitor, as shown in Fig. 22. This variable capacitor must be carefully protected from moisture. If it is not possible to achieve an SWR in the cable of less than 1.5, then the gamma matching length must be reduced and the adjustment must be repeated again.

Figure 22. Setting up gamma matching of an aluminum-copper antenna

If you have enough space and materials, you can install a continuous vertical wave VHF antenna. The wave antenna works more efficiently than the half-wave antenna shown in Fig. 20. A wave antenna provides a radiation pattern more close to the horizon than a half-wave antenna. The wave antenna can be matched using the methods shown in Fig. 21 and 22. The design of the wave antenna is shown in Fig. 23.

Figure 23. Continuous vertical wave VHF antenna

When making these antennas, it is desirable that the coaxial power cable be perpendicular to the antenna at least 2 meters. Using a balun in conjunction with a continuous antenna will increase its efficiency. When using a balun, it is necessary to use symmetrical gamma matching. The connection of the balun is shown in Fig. 24.

Figure 24. Connecting a balun to a continuous antenna

Any other known balancing device can also be used as an antenna balun. When placing the antenna near conductive objects, you may have to slightly reduce the length of the antenna due to the influence of these objects on it.

Round VHF antenna

If the spatial placement of vertical antennas shown in Fig. 20 and fig. 23 in their traditional vertical position is difficult, they can be placed by folding the antenna sheet into a circle. The position of the half-wave antenna shown in Fig. 20 in a “round” version is shown in Fig. 25, and the wave antenna shown in Fig. 23 in Fig. 26. In this position, the antenna provides combined vertical and horizontal polarization, which is favorable for communications with mobile and portable radio stations. Although, theoretically, the level of vertical polarization will be higher with the side feeding of round VHF antennas, in practice this difference is not very noticeable, and the side feeding of the antenna complicates its installation. The side feeding of the circular antenna is shown in Fig. 27.

Figure 25. Continuous round vertical half-wave VHF antenna

Figure 26. Continuous round vertical wave VHF antenna

Figure 27. Side feeding of round VHF antennas

A round VHF antenna can be placed indoors, for example, between window frames, or outdoors, on a balcony or on the roof. When placing a circular antenna in a horizontal plane, we obtain a circular radiation pattern in the horizontal plane and the operation of the antenna with horizontal polarization. This may be necessary in some cases when conducting amateur radio communications.

Passive "amplifier" of a portable station

When testing portable radios or working with them, sometimes there is not enough “just a little” power for reliable communication. I made a passive “amplifier” for portable VHF stations. A passive "amplifier" can add up to 2-3 dB to a radio station's on-air signal. This is often enough to reliably open the squelch of the correspondent station and ensure reliable operation. The design of a passive “amplifier” is shown in Fig. 28.

Figure 28. Passive “amplifier”

The passive “amplifier” is a fairly large tinned coffee can (the bigger the better). A connector similar to the antenna connector of a radio station is inserted into the bottom of the can, and a connector for connecting to the antenna socket is sealed into the lid of the can. 4 counterweights 48 cm long are soldered to the can. When working with a radio station, this “amplifier” is switched on between the standard antenna and the radio station. Due to the more efficient “ground”, the strength of the emitted signal increases at the receiving site. Other antennas can be used in conjunction with this “amplifier”, for example, an L/4 pin made of copper wire, simply inserted into the antenna socket.

Wideband survey antenna

Many imported portable radio stations provide reception not only in the amateur range of 145 MHz, but also in the survey ranges of 130-150 MHz or 140-160 MHz. In this case, for successful reception in the surveillance bands, where a twisted antenna tuned to 145 MHz does not work effectively, you can use a wideband VHF antenna. The antenna diagram is shown in Fig. 29 and the dimensions for different operating ranges are given in table. 1.

Figure 29. Wideband VHF vibrator

Table 1. Wideband VHF antenna dimensions

To operate the antenna, you can use a coaxial cable with a characteristic impedance of 50 Ohms. The antenna sheet can be made of foil and glued to the window. You can make the antenna sheet from aluminum sheet, or in printed form on a piece of foil fiberglass of suitable sizes. This antenna can receive and transmit in the specified frequency ranges with high efficiency.

Zigzag antenna

Some long-distance service VHF radio stations use antenna arrays consisting of zigzag antennas. Radio amateurs can also try to use elements of such an antenna system for their work. The view of an elementary zigzag antenna included in the design of a complex VHF antenna is shown in Fig. thirty.

Figure 30. Elementary zigzag antenna

The zigzag elementary antenna consists of a half-wave dipole antenna, which supplies voltage to the half-wave vibrators. In real antennas, up to five such half-wave vibrators are used. Such an antenna has a narrow radiation pattern pressed to the horizon. The type of polarization emitted by the antenna is combined - vertical and horizontal. To operate the antenna, it is advisable to use a balun.

In antennas used in service communication stations, a reflector made of a metal mesh is usually placed behind the elementary zigzag antennas. The reflector ensures one-way directivity of the antenna. Depending on the number of vibrators included in the antenna and the number of zigzag antennas connected together, you can obtain the required antenna gain.

Radio amateurs practically do not use such antennas, although they are easy to make for the amateur VHF bands of 145 and 430 MHz. To make the antenna sheet, you can use aluminum wire with a diameter of 4-12 mm from a power electrical cable. In the domestic literature, a description of such an antenna, for the fabric of which a rigid coaxial cable was used, was given in the literature.

Kharchenko antenna in the 145 MHz range

The Kharchenko antenna is widely used in Russia for television reception and in official radio communications. But radio amateurs use it to operate on the 145 MHz band. This antenna is one of the few that works very efficiently and requires virtually no adjustment. The Kharchenko antenna diagram is shown in Fig. 31.

Figure 31. Kharchenko antenna

To operate the antenna, you can use either 50 or 75 Ohm coaxial cable. The antenna is broadband, operating in a frequency band of at least 10 MHz on the 145 MHz band. To create a one-way radiation pattern, a metal mesh is used behind the antenna, located at a distance of (0.17-0.22)L.

The Kharchenko antenna provides a lobe width of the radiation pattern in the vertical and horizontal planes close to 60 degrees. To further narrow the radiation pattern, passive elements are used in the form of vibrators 0.45L long, located at a distance of 0.2L from the diagonal of the frame square. To create a narrow radiation pattern and increase the gain of the antenna system, several combined antennas are used.

145 MHz loop directional antennas

One of the most popular directional antennas for operating in the 145 MHz band are loop antennas. The most common in the 145 MHz band are two-element loop antennas. In this case, the optimal cost/quality ratio is obtained. The diagram of a two-element loop antenna as well as the dimensions of the perimeter of the reflector and the active element are shown in Fig. 32.

Figure 32. VHF loop antenna

Antenna elements can be made not only in the form of a square but also in the form of a circle or delta. To increase the radiation of the vertical component, the antenna can be fed from the side. The input impedance of a two-element antenna is close to 60 ohms, and both 50-ohm and 75-ohm coaxial cable are suitable for operation. The gain of a two-element VHF loop antenna is at least 5 dB (above the dipole) and the ratio of radiation in the forward and reverse directions can reach 20 dB. When working with this antenna, it is useful to use a balun.

Circular polarized loop antenna

An interesting circularly polarized loop antenna design has been proposed in the literature. Antennas with circular polarization are used for communication through satellites. Double feeding of the loop antenna with a phase shift of 90 degrees allows you to synthesize a radio wave that has circular polarization. The loop antenna power supply circuit is shown in Fig. 33. When designing an antenna, it must be taken into account that the length L can be any reasonable, and the length L/4 must correspond to the wavelength in the cable.

Figure 33. Circularly polarized loop antenna

To increase the gain, this antenna can be used in conjunction with a frame reflector and director. The frame must be powered only through a balun. The simplest balancing device is shown in Fig. 34.

Figure 34. The simplest balancing device

Industrial antennas in the 145 MHz range

Currently on sale you can find big choice proprietary antennas for the 145 MHz range. If you have money, of course, you can buy any of these antennas. Please note that it is advisable to purchase solid antennas already tuned to the 145 MHz range. The antenna must have a protective coating to protect it from corrosion by acid rain, which can fall in a modern city. Telescopic antennas are unreliable in city operating conditions and may fail over time.

When assembling antennas, you must strictly follow all instructions in the assembly instructions, and do not skimp on silicone grease for waterproofing connectors, telescopic connections and screw connections in matching devices.

Literature

1. I. Grigorov (RK3ZK). Matching devices 144 MHz range//Amateur Radio. HF and VHF.-1997.-No. 12.-P.29.
2. Barry Bootle. (W9YCW) Hairpin Match for the Collinear – Coaxial Arrau//QST.-1984.-October.-P.39.
3. Doug DeMaw (W1FB) Build Your Own 5/8-Wave Antenna for 146 MHz//QST.-1979.-June.-P.15-16.
4. S. Bunin. Antenna for communication through satellites // Radio.- 1985.- No. 12.-S. 20.
5. D.S.Robertson ,VK5RN The “Quadraquad” – Circular Polarization the Easy Way //QST.-April.-1984.-pages16-18.