Are you doing an installation and would like to learn how grounding a CB antenna works? Maybe you have already installed the CB antenna but upon testing the SWR (acronym for standing wave radio), you found it exceedingly high and now want to know how to better the grounding.
Or, you have noted that you are not receiving a good radio performance. Anyways, the first thing you need to do is assess the grounding. Let’s go over the process.
Grounding a CB Antenna: Bit by Bit Guide
Test the CB Antenna Grounding
To test your CB antenna grounding, you will need a digital multi-meter. A simple means of testing the grounding would be to assess the continuity between your car ground and your antenna mount. A well-grounded antenna mount translates to a well-grounded antenna.
Checking the continuity requires touching 2 locations with the probes of the multi-meter.
The first probe needs to touch the antenna mount. Where to place the probe?
Lay it where it’s touching the antenna mount. Let it lay flat across the mount but don’t let the probe touch the car.
The other probe ought to touch the car battery’s negative terminal. Be careful not to touch the battery’s positive terminal with the probe.
By the way, the positive terminal is marked by a ‘+’ sign while the negative one is marked by a ‘-’ sign.
In case you’re having trouble reaching the both the negative terminal and the antenna mount using the probes, seek out an ideal spot on the car and utilize it as the contact point of the 2nd probe.
Decoding the Continuity Results
If you can see the multi-meter’s needle moving completely to the right side once the probes come into contact with the terminals, that means the CB antenna mount’s grounding is good.
On the flip side, if there’s little to no needle motion, then you will know the antenna’s grounding needs to be worked on.
Fine grounding involves the establishment of a ground plane for the CB antenna.
But, before taking the results at face value, perhaps you should first test if the multi-meter is functioning correctly. To do that, touch the 2 probes together. A needle movement to the right indicates a good, working device while limited or no movement shows the multi-meter is broken.
What is a Ground Plane?
Also referred to as a counter poise, a ground plane denotes the CB antenna installation’s reflective unit; the antenna itself is the reactive part.
In a majority of antenna installations, the vehicle’s metal part, like the body or the chassis, functions as the ground plane.
Some systems don’t need a ground plane. Instead, they utilize the coaxial cable’s shield. Understand that the ground plane’s hardware and a no-ground plane system aren’t substitutable.
In case your antenna mount’s design accepts a coaxial plug, like the two-ended PL259, then your work is pretty easy. The only thing you need to do is ensure that the antenna mount is connected securely to the frame of your vehicle.
Perhaps your antenna’s mount rejects a coaxial plug. In that case, you will have to make a ground some other way.
You will find some people using a 10-gauge wire for grounding but braided ground strapping is much better, mainly due to its reactance.
The thing with reactance is that it can transform the wire to an antenna instead of a RF (acronym for radio frequency) ground. That’s contradictory with what you are looking to achieve.
Bonding is just another word for strapping. Its objective is to involve as much of the vehicle’s metal for grounding.
For those with unibody vehicles, things are much easier especially with regards to outgoing and incoming RF interference. That is due to the fact that everything is welded together. Nevertheless, some of these vehicles have sound barriers for the exhaust and engine system. These need bonding for the provision of optimal continuity for the RF signals.
Vehicles that have a body and frame, such as pickup trucks, need bonding regardless of where you’re mounting the antenna.
If yours is a truck, be sure to bond the bed’s 4 corners to the cab and the chassis to avoid a ground loop, which is often mistaken for a RFI at times.
While making up your mind regarding the manner in which you’re going to ground the antenna, keep in mind that using as much of your vehicle’s metal increases the antenna’s efficiency.
To bring the metal together, bonding all the metal parts using several ground straps in dissimilar spots might be necessary. Moreover, this will insure your work against the negative power lead’s accidental floating. On the same note, you want to avoid running a strap from the mount all the way to the battery.
One means of grounding is via the trunk lid.
A screw beneath the trunk’s lip would be a perfect location for grounding the system. However, as the trunk lid’s hinges possibly won’t get a proper ground, adding another ground strap might be necessary. To pull that off, take a short flat braid and attach one of its sides to the trunk lid and the other to the frame.
Ensure you have left adequate length to allow the lid to open but do not leave too much length that the strap becomes too baggy.
Another means of grounding, similar to the one we’ve just discussed, is through a close door. In case you go for the door, run a ground from the door pillar to the door to create a door hinge bypass.
Remember, the most vital part of creating a good ground is attaching the ground to the metal parts instead of plastics or other objects. Also, placing the coaxial cable’s hot side to the antenna is very important.
The side coming from the coaxial cable’s shield is the ground. Here are a few extra suggestions for means of grounding your antenna:
After you establish a proper ground, you shouldn’t have any more trouble with your CB antenna.
Feel free to share the results with us through the comments.
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