motskyroonmatick wrote: For mutant vehicles be aware of Ground Plane concerns. If you can not install your antenna on or directly next to a large somewhat flat well grounded metal area then you may have an insufficient ground plane which would eventually burn out the crystals in your CB radio.
The best location for an antenna is in the middle of a large grounded flat sheet metal plane. The top of a school bus would be ideal. Mirror mounts come close in my experience.
I ended up getting 3 no ground plane kits to solve my ground plane issues with the golf cart and my mostly plywood mutant vehicle. Now if my SWR meeter is what is causing the problem then that is all for naught.
OK gotta clear up some misinformation.
CBs haven't had crystals in them for decades, and when they did, they were for frequency control and had nothing to do with the transmitter's "final stage" amplifier, which is usually transistors.
The lack of a groundplane also has absolutely zero to do with whether your radio will fry. You can properly tune an antenna without a groundplane the same as with one. Thousands of boats have radios, both VHF and CB, and are fiberglass, no groundplane.
A groundplane is for is modifying the radiation or signal pattern of the antenna. Without a groundplane, it will radiate much of it's signal upward instead of down lower to the ground and outward, where it's more useable.
The groundplane simulates the other half of a half-wave length antenna, sort of similar to putting half of something on a mirror, making it act like a full-wave antenna. Full-wave length antennas do not need groundplanes. On CB frequencies, a full wavelengh is about 36 feet, too long for practical antenna size, so "half-wave" antennas are popular. Antennas can be made any physical length by coiling some of the length... that's the "loading coil" you see on shorter antennas.
A groundplane will make a less-than-full-wave antenna more effective by concentrating more of it's signal pattern closer to the ground rather than wasting it skyward.
If the "K30" antennas Sail Man mentioned are actually "K40" CB antennas, yes, use them, those are some of the best CB antennas ever made. Years ago some friends and I did a lot of field testing, the K40 was hard to beat.
Twin mirror-mount antennas are another way to modify the radiation pattern. To work properly they should be at least 8 feet apart. What happens is the signal pattern resembles a figure 8 as viewed from above, stronger to the front and rear, weaker to the sides. Truckers originally did this to maximize performance up and down the highway and reduce interference from whatever city they were passing through.
When I've used CB on the playa, channel clogging was zero issue. Very few people are on CB out there. The vast majority of people are on foot or bikes and not carrying a CB.
No, the antenna doesn't need to be bolted down to it's groundplane. It's not being "grounded" the way a power circuit is. A magnet mount is fine.
You can change your antenna's radiation pattern by moving it around relative to the groundplane, or metal surface, it's sitting on. The signal strength will be greatest toward the bulk of your groundplane surface; if you mount the antenna toward the rear of the bus, it's signal will be strongest toward the front.
We used to hang an antenna straight off the back of cars and drive in tight circles while watching a large signal-strength meter to track people down. The signal would be strongest toward the front of the car because of the groundplane effect, so when we got the highest reading we knew we were pointing in the direction of the signal. It works transmitting as well as receiving.