CB Radio Antenna Mounting – Step By Step Guide
A key step to getting the best performance from your CB radio is how you mount your CB antenna to your vehicle. By making some astute decisions and with the right techniques, you can optimize performance to make the best of your situation.
Here we go through the key steps to mounting your antenna.
Key steps to mounting a CB Antenna:
- Decide the best position for your CB antenna
- Prepare the antenna equipment for your CB antenna
- Attach the antenna bracket to your vehicle in a suitable position
- Ground the antenna mount and bracket
- Attach the antenna to your antenna mount
- Make sure the antenna mount and coaxial cable are grounded and the antenna is not grounded
- Safely and securely connect the coaxial cable to your CB radio
- Take suitable steps to protect your antenna, mount, cables, and your vehicle from the elements
- Once mounted, check the standing wave ratio using an SWR meter
- Tune your antenna for optimal transmission across the 40 CB channels
In theory, the best CB antenna is 102 inches long, mounted in the middle of a large, flat, metal surface, properly grounded, sturdily mounted and has the shortest, straightest coaxial cable connecting it to the CB radio.
In practice, mounting an CB antenna is a series of compromises between optimal antenna performance and the practicalities of your situation. Your CB radio experience will be impacted by the length of your CB antenna, where and how you position it, the size and shape of the ground plane, and how well you tune your CB antenna once it is installed.
Detailed 10 Key Steps to Mount a CB Antenna
1. Decide the best position for your CB antenna
Assess where you can attach your CB antenna and decide the best position for your situation.
The mounting position will impact CB antenna performance. The higher the better, ideally with most of the antenna reaching above the roof line of your vehicle. Just remember to consider road traffic height restrictions that may exist in your area and the places you travel to.
If you have a coil antenna, try and position your antenna so the coil is above roof line for best performance. The more centrally placed the CB antenna mount, the better the ground plane.
If possible, avoid mounting your antenna on isolated places like your bumper bars or spare wheel plate as you won’t access such a great ground plane. Lots of people do mount them there, just bear in mind it is not optimal.
Some questions you have to consider are:
How willing and able are you to make alterations to your vehicle?
Are you comfortable or able to drill holes and create access points on your vehicle?
Drilling holes in the roof or mounting antenna elsewhere can result in damage and rust and may impact the resale value of your vehicle, but may give you the best options for good antenna transmission.
You can find out more about CB antenna placement tips in this short video:
2. Prepare the antenna equipment for your CB antenna
Once you have decided where to attach your antenna, make sure you have the right parts to install your antenna including:
- Antenna mount and associated washers (this should all come as part of your antenna mount kit)
- Antenna bracket
- Coaxial cable
- Tool kit and sander
Buy, or make, the antenna bracket which will hold your antenna in position. Most antenna brackets you buy will be coated in paint or a powder coat.
To prepare your bracket for grounding, make sure the hole where the base of the antenna mount fits through and the hole which holds the grounding cable have the coating sanded away to expose the metal underneath.
The following video from 1:20s to 1:50s has a good example of where the metal of the bracket should be exposed.
3. Attach the antenna bracket to your vehicle in a suitable position
Make sure the grounding cable, the coaxial cable, and the antenna mount have access to attach to the bracket. Where possible make sure the wires are protected and will sit behind the external parts of the vehicle to protect them from the elements and excessive heat or wet.
Tip: Don’t attach the bracket too firmly or permanently at this stage. It is better to test your antenna can transmit and receive before making an irreversible installation. Once you are satisfied with your performance, go ahead and make sure everything is securely fitted to your vehicle.
4. Ground the antenna mount and bracket
Attach one end of the grounding cable to the antenna bracket so it sits flush onto the exposed metal of the bracket. Run the other end of the grounding cable to the metal chassis of the vehicle and bolt it into place securely and cleanly.
This may require cleaning layers of dirt and grime from your placement position beneath the car before installing. Make sure it is bolted firmly, and the grounding wire is flush and tight against the vehicle, so it doesn’t catch and snag.
The following video shows an example of putting in the grounding cable, check from 2m 10s to 3m 50s:
Attach the antenna mount to the bracket. The bottom of the antenna mount, which attaches to the coaxial cable, sits on the side of the bracket where the metal has been exposed. This ensures the antenna mount and coaxial cable are properly grounded.
For 3/8 inch screw-type antennas, a plastic washer, or similar insulated material will separate the grounded parts of the set up from the antenna itself which must remain insulated.
Check from 3:40s to 6:00 of the following video demonstrates this visually:
Note that for coaxial mounted antennas (UHF/SO239/NEMA), the outer screw must be grounded.
5. Attach the antenna to your antenna mount
Follow the instructions of your antenna installation manual to attach the antenna to the antenna mount.
When you come to tune your antenna, after establishing that the antenna mount is properly grounded and the antenna is well positioned, you can use washers to adjust the height of your antenna to get the best transmission quality. Tuning your antenna only requires very small adjustments to its height.
6. Make sure the antenna mount and coaxial cable are grounded and the antenna is not grounded
Make sure the bottom of the antenna mount where the coaxial cable connects is grounded and that the antenna bracket is grounded. You can test this using an ohm meter unit, but make sure the coaxial cable is disconnected when you do this so you are only testing the bracket, then the antenna mount to get a resistance reading.
Next make sure the antenna itself is not grounded by ensuring you have an infinity or open line reading.
Tip: From time to time, check the grounding of your antenna, antenna mount and bracket, especially if your SWR readings become high.
7. Safely and securely connect the coaxial cable to your CB radio
Where possible test if your antenna works properly before making permanent changes to your vehicle.
Use available vents and holes in your vehicle to feed the coaxial cable through to the vehicle interior where it connects to your CB radio.
Keep the cable as short as possible and make sure it is not unnecessarily coiled or loose.
Tip: Wherever possible, make sure your cable is tucked away and not exposed to avoid catching or snagging.
8. Take suitable steps to protect your antenna, mount, cables, and your vehicle from the elements
If you drill holes to mount the antenna, feed the cables, or install the bracket, consider using dielectric grease, and other protective steps to prevent exposed metal. Do what you can to minimize scratches to paintwork during installation to prevent rust.
9. Once mounted, check the standing wave ratio using an SWR meter
An SWR meter reading above 1:2 indicates your antenna is not set up properly.
If the meter reading is above 1:3 do not try and transmit over your CB radio as you are likely to permanently damage the most expensive parts of your CB radio, rendering the equipment almost useless and expensive to repair.
To rectify it, check the position of your antenna. The higher you can place it the better, and the more centrally you can place it the better.
Make sure the antenna mount is properly grounded, and there is ground continuity to the radio itself (i.e., the CB radio itself, must also be grounded).
10. Tune your antenna for optimal transmission across the 40 CB channels
When the SWR reading for channel 1 and for channel 40 is about the same, and below 1:1.5, your antenna is well-tuned.
If the reading for one channel is higher than the other, the antenna is too short or too high and tiny adjustments of a few millimeters in height of the antenna will help rectify the tuning so you get the best reception across all 40 channels.
What is a ground plane and why is grounding important?
A good ground plane improves your ability to transmit by enhancing the functionality of your CB antenna. The best kind of ground plane is a flat surface, like the roof of your car.
In simple terms, when you transmit, the ground plane effectively becomes part of your antenna by reflecting the radio waves from your antenna.
The size and shape of a ground plane determine the effectiveness of your antenna – you can get equipment that enhances your ground plane.
You can get CB antennas that don’t need a ground plane and operate without a large metal surface beneath them. These are useful if you plan to use them on fiberglass boats or cars.
If your CB antenna is not properly grounded, it will be almost impossible to tune it and you risk damaging your radio equipment due to high SWR.
The way to ground your CB antenna is by making sure the CB antenna mount is directly connected to the vehicle’s metal frame, normally achieved by running a grounding strap from the mount and fixing securely to the chassis.
In an ideal world, your CB radio antenna would be 102 inches long and securely mounted high and centrally on your vehicle to get the best range.
In the real world, this is largely impractical due to road height clearances and how far you are prepared to go to make adjustments to your vehicle when installing CB radio equipment.
However, with carefully thought-through compromises, the right installation, and the right CB antenna choice for your needs, you can achieve a decent range and good transmission.