No products in the cart.


The AUSCB.AU Page is here to help with common hints and tips for CB use’s on 27MHz HF CB or 476/477MHz UHF CB. These tips will hopefully help new uses enjoy and get the most out of CB Radio.

Citizen band radio stations class licence

The class licence lets you use citizen band (CB) radios to communicate over short distances. 

What this class licence lets you do

You can use CB radio to communicate over short distances via the Citizen Band Radio Service (CBRS).

You can use the CBRS for:

  • any voice communications
  • telemetry and telecommand

All users operate on shared frequencies.

Licence rules

You don’t need to apply for a class licence or pay any fees with the ACMA.

But you must follow all the rules in the:

Power output

Your equipment cannot exceed the maximum power stated in the class licence.

  • HF AM – 4 watts
  • HF SSB – 12 watts
  • UHF FM – 5 watts

Frequencies for CB radios

You can find the frequencies for CB radios in schedule 1 of the class licence.

You can only use CB radios on designated channels in these frequencies:

  • HF – 26.965 MHz to 27.405 MHz (inclusive)
  • UHF – 476.4125 to 477.4125 MHz (inclusive)

You can only use telemetry and telecommand on UHF channels 22 and 23. You cannot speak on these channels.

Packet radio and other types of data operation are not allowed on CB bands.

If you want to use other frequencies, you must apply for an apparatus licence.

UHF CB repeater stations

Icom IC-FR6000

To operate a CB repeater station, you need an apparatus licence.

If you are near a repeater station, you can operate a CB radio station through the CB repeater station but only:

  • In the UHF band
  • on the repeater’s assigned channels

Channels 1 to 8 and 41 to 48 are repeater output channels. Channels 31 to 38 and 71 to 78 are the matching repeater input channels.

For example, a repeater that transmits on Channel 1 will always receive on Channel 31.

If you operate your CB radio in duplex or repeater mode, it will automatically select the matching frequency.

Please note that if there is a repeater station in the area, you should not use the repeater channels to communicate on a single frequency. Be aware that these can interfere with a repeater station, even if it’s a long way away.

Contacting other CB users for the first time

There are 2 channels you can use to contact other CB users for the first time.

These are:

  • Channel 11 (AM) (27.085 MHz) and Channel 16 (SSB) (27.155 MHz) in the HF band
  • Channel 11(FM) (476.675 MHz) in the UHF band

After you’ve made contact, you should move to another channel that’s not in use. This leaves the channel available for other users to contact each other.

Call channels are legislated assignment


ACMA has set aside 2 channels that are only for emergency messages:

  • Channel 9 (27.065 MHz) in the HF band
  • Channels 5/35 (476.525/477.275 MHz) in the UHF band

But you can use any CB frequency to attract attention in an emergency. If you have mobile phone service Dial 000 or 112 for Police, Fire and Ambulance

Emergency channels are legislated assignment

Telemetry and Telecommand Channels

On UHF Channels 22 (476.950 MHz) & 23 (476.975 MHz) are dedicated telemetry and telecommand channels, no voice communications are allowed. Used mostly by farmers.

Examples include:

  • Monitoring water levels in dams
  • Controlling equipment such as irrigation pumps
  • Opening and closing gates
  • Radio ID
  • GPS information

Miscellaneous Channels by convention

  • HF Channel 8 AM (27.055 MHz) highway/Road
  • HF Channel 35 LSB (27,355 MHz) unofficial LSB calling channel
  • UHF Channel 10 FM (476.650 MHz) used 4×4 convoy & national parks
  • UHF Channel 18 FM (476.850 MHz) used by caravan and motorhomes in convoy
  • UHF Channel 29 FM (477.125 MHz) Pacific Hwy (NSW) & Bruce Hwy (QLD)
  • UHF Channel 30 FM (477.150 MHz) Local Alert & Broadcasts Channel
  • UHF Channel 40 FM (477.400 MHz) Highway/Road

Selective Calling methods

If you want to use selective calling, you can only use these methods:

  • Selective calling (Selcall) allows a radio to call another radio using a sequence of tones, usually presented to the user as a series of 5 numbers. UHF CB radios can be set to be completely silent until they receive a series of tones matching a pre-programmed sequence. Radios which have this feature usually indicate that a call has been received by emitting a number of beeps and by opening the squelch. The popularity of selcall has dropped since the introduction of CTCSS. SelCall may be used on UHF.

HF Selcall uses CCIR 493-4, 4-digital or 6-digit numbering system. The calling radio emits a data steam while the receiving radio being called will indicate a call has been received by emitting a number of beeps and by opening the squelch. If you would like to use selcall on HF CB you could use a Jannel SC2 Selcall/Telcall Microphone or a SC51 – Selcall/Telcall/GPS internal module.

CCIR-1 5-Tones used on UHF CB
HF CCIR 493-4 Selcall
  • Continuous tone coded squelch system (CTCSS) allows a group of radios set with the same tone to converse on a channel without hearing other radios using that channel. CTCSS can be used to silence a radio until another radio with the same tone transmits. This allows monitoring of a channel for transmissions from radios set with the same tone without hearing other conversations that use different or even no tone. May be used on UHF CB.

  • CDCSS or Digital Code Squelch (DCS) is a further development of the continuous tone-coded squelch system or CTCSS that uses a slow-speed, binary data stream passed as sub-audible data along with the transmission. Motorola calls this Digital Private Line or DPL. It consists of a 23-bit telegram sent repeatedly on the channel at 134 bits per second along with the voice transmission. This allows for over 100 possible fleet codes to be used. This gives it an advantage over the CTCSS tones in that there are more possible codes to use; however, it does use more bandwidth and can be affected by voice tones below 300 Hz if not properly filtered by the radio circuitry. May be used on UHF CB.

The use of CTCSS & DCS are not permitted on UHF CB repeaters or the designated emergency channels.

Call signs

Call signs are a unique series of letters and numbers. They make it easy to identify a station.

You do not need to use a call sign for class licences. But it’s recommend that you identify yourself when you communicate by CB radio.

UHF CB Channel List

Channel Name:Frequency:Purpose:*Frequency Spacing:
Channel 1476.4250Repeater Output12.5 kHz / 25 KHz
Channel 2476.4500Repeater Output12.5 kHz / 25 KHz
Channel 3476.4750Repeater Output12.5 kHz / 25 KHz
Channel 4476.5000Repeater Output12.5 kHz / 25 KHz
Channel 5476.5250Emergency Repeater Output / Simplex12.5 kHz / 25 KHz
Channel 6476.5500Repeater Output12.5 kHz / 25 KHz
Channel 7476.5750Repeater Output12.5 kHz / 25 KHz
Channel 8476.6000Repeater Output12.5 kHz / 25 KHz
Channel 9476.6250General Channel12.5 kHz / 25 KHz
Channel 10476.65004WD Clubs or Convoys and National Parks.12.5 kHz / 25 KHz
Channel 11476.6750Call Channel12.5 kHz / 25 KHz
Channel 12476.7000General Channel12.5 kHz / 25 KHz
Channel 13476.7250General Channel12.5 kHz / 25 KHz
Channel 14476.7500General Channel12.5 kHz / 25 KHz
Channel 15476.7750General Channel12.5 kHz / 25 KHz
Channel 16476.8000General Channel12.5 kHz / 25 KHz
Channel 17476.8250General Channel12.5 kHz / 25 KHz
Channel 18476.8500Caravanners and Campers Convoy Channel12.5 kHz / 25 KHz
Channel 19476.8750General Channel12.5 kHz / 25 KHz
Channel 20476.9000General Channel12.5 kHz / 25 KHz
Channel 21476.9250General Channel12.5 kHz / 25 KHz
Channel 22476.9500Telemetry and Telecommand Only (No Voice)25 kHz
Channel 23476.9750Telemetry and Telecommand Only (No Voice)25 kHz
Channel 24477.0000General Channel12.5 kHz / 25 KHz
Channel 25477.0250General Channel12.5 kHz / 25 KHz
Channel 26477.0500General Channel12.5 kHz / 25 KHz
Channel 27477.0750General Channel12.5 kHz / 25 KHz
Channel 28477.1000General Channel12.5 kHz / 25 KHz
Channel 29477.1250Highway Channel, Pacific Hwy (NSW) & Bruce Hwy (QLD)12.5 kHz / 25 KHz
Channel 30477.1500Local Alert & Broadcasts Channel12.5 kHz / 25 KHz
Channel 31477.1750Repeater Input12.5 kHz / 25 KHz
Channel 32477.2000Repeater Input12.5 kHz / 25 KHz
Channel 33477.2250Repeater Input12.5 kHz / 25 KHz
Channel 34477.2500Repeater Input12.5 kHz / 25 KHz
Channel 35477.2750Emergency Repeater Input / Simplex12.5 kHz / 25 KHz
Channel 36477.3000Repeater Input12.5 kHz / 25 KHz
Channel 37477.3250Repeater Input12.5 kHz / 25 KHz
Channel 38477.3500Repeater Input12.5 kHz / 25 KHz
Channel 39477.3750General Channel12.5 kHz / 25 KHz
Channel 40477.4000Highway/Road Channel Australia Wide12.5 kHz / 25 KHz
Channel 41476.4375Repeater Output12.5 kHz
Channel 42476.4625Repeater Output12.5 kHz
Channel 43476.4875Repeater Output12.5 kHz
Channel 44476.5125Repeater Output12.5 kHz
Channel 45476.5375Repeater Output12.5 kHz
Channel 46476.5625Repeater Output12.5 kHz
Channel 47476.5875Repeater Output12.5 kHz
Channel 48476.6125Repeater Output12.5 kHz
Channel 49476.6375General Channel12.5 kHz
Channel 50476.6625General Channel12.5 kHz
Channel 51476.6875General Channel12.5 kHz
Channel 52476.7125General Channel12.5 kHz
Channel 53476.7375General Channel12.5 kHz
Channel 54476.7625General Channel12.5 kHz
Channel 55476.7875General Channel12.5 kHz
Channel 56476.8125General Channel12.5 kHz
Channel 57476.8375General Channel12.5 kHz
Channel 58476.8625General Channel12.5 kHz
Channel 59476.8875General Channel12.5 kHz
Channel 60476.9125General Channel12.5 kHz
Channel 61476.9375Reserved, Guard channel for 22 & 23
Channel 62476.9625Reserved, Guard channel for 22 & 23
Channel 63476.9875Reserved, Guard channel for 22 & 23
Channel 64477.0125General Channel12.5 kHz
Channel 65477.0375General Channel12.5 kHz
Channel 66477.0625General Channel12.5 kHz
Channel 67477.0875General Channel12.5 kHz
Channel 68477.1125General Channel12.5 kHz
Channel 69477.1375General Channel12.5 kHz
Channel 70477.1625General Channel12.5 kHz
Channel 71477.1875Repeater Input12.5 kHz
Channel 72477.2125Repeater Input12.5 kHz
Channel 73477.2375Repeater Input12.5 kHz
Channel 74477.2625Repeater Input12.5 kHz
Channel 75477.2875Repeater Input12.5 kHz
Channel 76477.3125Repeater Input12.5 kHz
Channel 77477.3375Repeater Input12.5 kHz
Channel 78477.3625Repeater Input12.5 kHz
Channel 79477.3875General Channel12.5 kHz
Channel 80477.4125General Channel12.5 kHz

* Channel bandwidth 25KHz is only used by older UHF CB 40 channel sets, while 12.5KHz is used by all new 80 Channel sets.

You should not use repeater input channels 31 – 38 & 71- 78 for simplex operation (radio to radio), interference to repeaters is possible. If you intend on using repeater inputs for simplex (radio to radio), make sure you check for a repeater in the area you intend to operate in.

HF CB Channel List

Channel: 23/40Australian Channel: 18Frequency In MHz:Purpose:
Channel 1N/A26.965General Channel AM/SSB
Channel 2N/A26.975General Channel AM/SSB
Channel 3N/A26.985General Channel AM/SSB
Channel 4N/A27.005General Channel AM/SSB
Channel 5Channel 127.015General Channel AM/SSB
Channel 6Channel 227.025General Channel AM/SSB
Channel 7Channel 327.035General Channel AM/SSB
Channel 8Channel 427.055Highway/Road Channel
Channel 9Channel 527.065AM/SSB (USB) Emergency Channel
Channel 10N/A27.075General Channel AM/SSB
Channel 11Channel 627.085AM Call Channel
N/AChannel 727.095Withdrawn From Service
Channel 12Channel 827.105General Channel AM/SSB
Channel 13Channel 927.115General Channel AM/SSB
Channel 14Channel 1027.125General Channel AM/SSB
Channel 15Channel 1127.135General Channel AM/SSB
Channel 16Channel 1227.155SSB (LSB) Call Channel
Channel 17Channel 1327.165General Channel AM/SSB
Channel 18Channel 1427.175General Channel AM/SSB
Channel 19Channel 1527.185General Channel AM/SSB
N/AChannel 1627.195Withdrawn From Service
Channel 20Chanel 1727.205General Channel AM/SSB
Channel 21N/A27.215General Channel AM/SSB
Channel 22Channel 1827.225General Channel AM/SSB
Channel 23N/A27.245General Channel AM/SSB
Channel 24N/A27.235General Channel AM/SSB
Channel 25N/A27.255General Channel AM/SSB
Channel 26N/A27.265General Channel AM/SSB
Channel 27N/A27.275General Channel AM/SSB
Channel 28N/A27.285General Channel AM/SSB
Channel 29N/A27.295General Channel AM/SSB
Channel 30N/A27.305General Channel AM/SSB
Channel 31N/A27.315General Channel AM/SSB
Channel 32N/A27.325General Channel AM/SSB
Channel 33N/A27.335General Channel AM/SSB
Channel 34N/A27.345General Channel AM/SSB
Channel 35N/A27.355General Channel
(Unofficial LSB calling channel)
Channel 36N/A27.365General Channel AM/SSB
Channel 37N/A27.375General Channel AM/SSB
Channel 38N/A27.385General Channel AM/SSB
Channel 39N/A27.385General Channel AM/SSB
Channel 40N/A27.405General Channel AM/SSB

Did you know in Australia we have a 27MHz marine band?

The Australian 27MHz marine band is in the upper portion of the band. 10 channels have been allocated, mods used on this band are AM and USB and the power output is the same as 27MHz CB 4w AM and 12w SSB.

The use of the channels are for Australian water ways. They come under a class license like CB radio no marine radio qualification needed unlike VHF. The use of 27MHz marine has reduced over time as equipment is harder to purchase. Unlike VHF marine that uses FM the AM/USB sets are susceptible to noise from engines on the vessel.

The early radio sets had the 10 channels marked from 1 to 10. later set’s then used channels marked from 68 to 98, this was formed from the frequency used, i.e. 27.8800 is channel 88.

 Distress & Calling Channels

Like CB radio Marine also has emergency channels (Distress and Calling) these are allocated under law from the Australian Communications and Media Authority (ACMA). Channels allocated for are:

  • Channel 88 used as the Maine Distress and calling.
  • Channel 86 used as a secondary to 88.

A majority coast station monitor 27MHz Marine channels 88 & 86. In recent times some coast stations have stopped monitoring 27MHz marine. Please check with your local Coast Gaude before heading out!!

It’s recommended that vessels are equip with a VHF marine transceiver and a qualified person on board (most likely the Skipper). For more information see ACMA at https://acma.gov.au

Calling on 88 and 86 used to log in and out from the Coast Guard. you can call other station as well, once you have made contact with the other vessel or land station you need to move to the appropriate channel I.e. Channel 94.

27MHz Marine Antennas

Like 27MHz CB there are lots of antennas for use with 27MHz marine from the helical, 9-foot stainless steel, and base station antennas. Base station antennas like the Shockwave Station master or pre-tuned types from ZCG scalar range. As for Vessel mount type antennas there are of course the Helical with the 5/16 base and 9′ stainless steel antennas, this type of antenna works well on Steel or Aluminum decks as this is used for a ground plane much like on a car. Ground independent deck mount antennas typically use a marine antenna mount, plastic or metal and can be used on fiberglass vessels. Most antennas come pre-tuned and don’t need adjustment, but you should check your SWR after installation is finished.

Current Radios available

Uniden UM255, AM Marine and AM 40 Channel CB.

GME GX400W/B AM Marine.

HF 27MHz Marine Channel List

ChannelFrequency Purpose & Mode
6827.6800Commercial calling and working – AM/USB
7227.7200Professional fishing calling and working (Ship-Shore/Ship-Ship) – AM/USB
8227.8200Professional fishing calling and working (Vessel-Shore/Ship-Ship) – AM/USB
8627.8600Supplementary distress, safety and calling. – AM/USB
8827.8800Maine distress, safety and calling. – AM/USB
9027.9000 Non-commercial calling, public use and working (Vessel-Shore) – AM/USB
9127.9100Non-commercial calling, public use and working (Vessel-Shore) – AM/USB
9427.9400Non-commercial calling, public use, club events and working.
(Vessel-Vessel/Vessel-Shore) – AM/USB
9627.9600Non-commercial calling, public use (Vessel-Vessel) – AM/USB
9827.9700Rescue organizations, e.g. surf rescue, volunteer coast guard.
(Vessel-Vessel/Vessel-Shore) – AM/USB

Did You Know We 27MHz Handphone?

This class license lets you use a 27 MHz handphone station equipment (Handhelds) to communicate by radio. 

What this class license lets you do

This class licence lets you use a 27 MHz handphone (Handheld) station.  

Handphones have a built-in antenna and you can carry them by hand. They make it easy to talk to another person who is a short distance away.

They are often used for or:

  • by bushwalkers and firefighters
  • during sporting events and group activities
  • to communicate with someone who is less than 1km away

All users operate on shared frequencies.

Licence rules

You don’t need to apply for a class licence or pay any fees.

But you must follow all the rules in the:

Power output

Your equipment cannot exceed the maximum power stated in the class license of

700mW pZ, 4W pZ and 12 Px. See table below.

Frequencies for 27 MHz handphones

Frequency in MHzMode / Power / BandwidthPurpose / Note’s
27.230AM / 700mW pZ / 6KhzGeneral Use ** Refer to note.
27.240AM / 700mW pZ / 6KhzGeneral Use ** Refer to note.
27.250AM / 700mw pZ / 6KhzGeneral Use ** Refer to note.
27.260AM / 700mW pZ / 6KhzGeneral Use ** Refer to note.
27.270AM / 700mW pZ / 6KhzGeneral Use ** Refer to note.
27.280AM /700mW pZ / 6KhzGeneral Use ** Refer to note.
27.550AM / 4W pZ / 6Khz – USB / 12w Px /3KHzGeneral Use.
27.560AM / 4W pZ / 6Khz – USB / 12w Px /3KHzGeneral Use.
27.580AM / 4W pZ / 6Khz – USB / 12w Px /3KHzBushfire fighting purposes only.
27.590AM / 4W pZ / 6Khz – USB / 12w Px /3KHzGeneral Use.
27.620AM / 4W pZ / 6Khz – USB / 12w Px /3KHzGeneral Use.
27.660AM / 4W pZ / 6Khz – USB / 12w Px /3KHzGeneral Use.
27.760AM / 4W pZ / 6Khz – USB / 12w Px /3KHzGeneral Use.

NOTE: If you use the frequencies with notation ** you:

  • must not interfere with citizen band (CB) HF radio stations.
  • may get interference from CB equipment that uses the industrial, scientific and medical (ISM) frequency band.

Problems with interference or reception

You may get interference if you use 2 handphones near each other or class to other services in the band on or around same frequency.

If this happens, try changing to another frequency.

You can use selective calling under this class licence.

Antennas, cable and Placement

Choosing the right antenna for you home base or mobile will depend on a few factors.

Type of antenna, gain, height above grand, purpose base or mobile, HF or UHF and the type of feedline required.

  • Vertical Antenna base
  • Vertical Mobile Antenna
  • Yagi (Beam) Directional Antenna


Most people know co-ax cable for their TV set RG6 and RG59 75 Ohm type although similar the co-ax cable used for CB has an impedance of 50 Ohms common cables are RG213, RG58U and RG58C/U.

RG58 is commonly used in mobile installations as it’s small and we only have a short run of normally 10m or less. while in a base station we would tend to use RG213 for runs greater then 10m to 30m as RG213 has less loss per meter than RG58. There are better cables out there like LMR400 (LL400) recommended for use with UHF CB, but for basics we will stick to RG213, RG58U and RG58C/U.

RG213 and RG58C/U have a multi core centre conductor, RG58U has a solid centre conductor. other cable s like LMR400 (LL400) that also have a foil shield have less loss and are used for UHF and higher. The foil also helps to reduce noise that may be induced by local equipment.

If you plan to mount your antenna on a boot (trunk) lid use RG58C/U as it’s less prone to fatigue.


There are many types of connectors used for CB radio from the humble PL259 (UHF), N type, BNC, FME & SMA. Same cables come with an FME/PL259 adapter so you can pass the cable though the firewall of your vehicle.

Did you know the SO239 comes in two flavours?

SO239 (UHF): Connectors in the UHF connector family mate using the 58 inch 24 tpi threaded shell for the shield connection and an approximately 0.156 inch-diameter (4 mm) pin and socket for the inner conductor.

M Connector: Similar connector to the SO239 (M connectors) has an incompatible 16mm diameter, 1mm metric thread, but these are not standard SO239 connectors and do not play well with the older SO239. M connector commonly used by Diamond Antenna Corporation in Japan.

Before fitting your connector cut a piece of dual wall heat shrink and slide it over your cable, fit your connector use the heat shrink to cover the entry point of the cable and connector. This dose too things, seal the connector at the cable entry point and provides some strain relief.

Sealing connectors is a must when out in the weather. It will reduce the risk of antenna system failure. Using some self-amalgamating tape like 3M SCOTCH 23 wrapping the connector and cable, finely wrapping with a layer of PVC tape like 3M SCOTCH 33+ or Nito tape to protect it from UV.

Mobile Antenna Placement

When installing your antenna there are some factors you may wish to consider, I.e., In a mobile installation if you have a ground dependent antenna the more metal surface you have for the ground plane the better, but with the length of a lot of them it may not be practical to center roof mount antenna. see the picture below that shows the antenna radiating pattern in different locations.

After selecting your mounting location for your antenna base you make need to prepare the surface. If mounting to a painted surface, it’s a good idea to remove any paint from under neath so the earth of the antenna base can clean connection to the metal surface. This is particularly important when installing ground dependent antennas like the Mobileone Bush Bandit 27Mhz Antenna DX160RW, this will help SWR and the antenna performance.

Fitting Antenna’s to a Vehicles

With so many different types of two-way radio antenna’s installing them need to be practical and efficient. This also means installing them so that you meet the requirements of your state and territory.

Rules and guidelines:

  • VictoriaDownload
  • New South WalesDownload (General rule for fitting options) Don’t install antennas in drivers view. left as practical keeping antenna separation.
  • Australin Capital TerritoryDownload
  • TasmaniaDownload
  • South Australia – TBA
  • Westen Australia – TBA
  • Northen TerritoryDownload
  • QueenslandDownload

We are trying to compile the information for each state and territory. And where we can have highlighted the appropriate section in yellow. It’s very important to know that in same states and territories mounting on the front can be very gray, in the front of the driver. It is recommended that the installation of any antenna be mounted as close to the left as practical. The information provided is a guide only, If not sure contact your local roads authority.

Practical Mounting of Antennas

Ok we will need to look at a few different types of antennas and their mountings options. They are

UHF CB ground independent antennas, 3G/4G/5G LTE antennas HF antennas.

  • Starting off with the most common the UHF CB antenna. Most UHF CB antennas used today are ground independent they come mainly the raised feed type and the larger heavy duty 4×4 style antenna. with the smaller type of antenna like the raised feed you can mount this ether on a roof bar, bracket, fender mount or bull bar. the primary position would be on the roof bar or backet if practical secondary location would be fender, then bull bar. The heavy-duty UHF CB antennas are designed to be mounted on a bull bar and should have the mount (spring mount) on the top loop as to have the antenna clear of the bonnet. because they are very large in size and diameter it is recommended the mount to the left side of the vehicle as not to block the drivers view of the road.
  • 3G/4G/5G LTE antennas are for the most come in a few different types of small low gain (3.5dBi) for roof mount application and the larger 6.5 to 7.5dBi antennas that can be mounted on fender or bull bars. Agine when mounting them on a bull bar it’s a good idea to keep them as far left as practical. Because of the frequencies use for this service in the 700 to 3500MHz rage it’s best to keep them well away from other metallic objects.
  • HF Autotune and ground dependent antennas are one of the hardest to mount on cars 4×4’s we will start with the good old 27MHz CB antenna these come is a few flavors from the 9′ 1/4 wave to the 5′ helical antenna. This type of antenna needs a good ground plane for maximum performance, as they are quite large placing the smaller 6′ one on a gutter or roof mount is a good place to start, while the longer heaver antennas like the 9′ stainless steel or Skipwhip from Mobileone antennas are best mounted on a bull bare because of the wight and sine of the spring and base. Keep in mind you may need to bond the bull bare to the body of the vehicle with a 12mm or 20mm braided strap, this will help with antenna performance and tunning for the best possible SWR. Other HF antennas like the multi band tap antennas that cover from 2 to 30MHz also would be suited to bull bar mounting or on the back of some vehicles, again grounding with a strap will be needed. HF autotune antennas are very handy and convent because at the touch of a button you can tune the antenna for the desired frequency. They come in a few models I.e the taller Codan 9350 and the smaller 3040, the 9350 is very large antenna and need to mount about 100mm (10cm) away from any meatal substrate. As the tunning section of the antenna con be affected by the body most people mount this on the left of the bull bar and on the back. keep in mind this antenna can create blind spot in the drivers view. this is much the same for the 3040 the lower section can create a blind spot closer to the vehicle. with all autotune antennas good grounding is a must.
  • Antenna separation is another very important issue to look at. You will see from time to time mostly 4×4 with antennas mounted to the left witch is great for the driver but not so good for the antenna and equipment connected to it. It’s good practice to keep antennas as far apart and away from any metallic objects as possible. Antennas are part of a tuned system this help your equipment work at it best.

Somes problems with antenna installed to close to one another may cause the following:

  1. Detuning of antenna system which could damage the transceiver.
  2. RF energy from the transmitter could damage the receiver on the send radio.
  3. Diminish the performance and distance (range) your setup.
  4. It’s looks stupid!!

To help stop rust and corrosion use some electrical contact grease, a light film on the bear surface is all that is needed.

Mobile bases commonly used in Australia

The 5/15 TPI base are quite common and are used for antennas from small to 160cm CB antenna’s the difference between the two types of 5/16 bases is the way the co-ax is terminated. The VHF/UHF version was used on a lot a of Taxi’s with a 4.5dbi antenna. these bases may also be panel mounted in a roof of a vehicle.

The 1/2″ BSW base (also known as the SAM base) is used by some lager HF and 27MHz CB antennas like taped multi band, Mobileone Skip Whip and the classic 9′ stainless steel antenna. These antennas will also have a spring to help with shock, vibration and allows for the antenna to bend to reduce damage.

SO239 Also known as M base is used by a lot of commercial users in the VHF and UHF bands, some the antennas used are RFI antennas VHF and UHF, 27MHz CB base loaded, UHF CB and amateur radio dual band antennas like the SG-7900.

Base Used in the USA and abroad.

3/8 x 24 Stud mount, Used mostly in the USA for 27MHz CB and Amateur radio mobile antennas. Can come with SO239 (UHF) and eyelet styles termination.

3/8 x 24 Stud ball mount. The ball mount is designed to filled onto the vertical fender or other panel. The ball is adjustable to allow for radiator to be set vertically. this mount is very common with the 9-foot stainless steel whip and spring & other HF antennas.

Used mostly in the USA the NMO or “New Motorola Mount” is a mobile mount used for mobile VHF/UHF PMR, LMR, cellular phone, EMS, 27MHz CB, GRMS & amateur radio. The NMO mount is low profile making it ideal for panel fitment on the boot lid and roof. When installed correctly and a good quality antenna attached it makes for a watertight seal.

Light Reading

SGC HF Guide Book – From SGC USA.

HF Propagation

HF operation PDF

Here is a splendid video that shows and explains HF propagation aka Skip from Rohde Schwarz.

information brought to you by BNCom Australia / Australian Communications & Media Authority ,wikipedia and other sources.