This is really close and a good base explanation. I'm going to make a couple of corrections mostly for a future search of this thread.

First... Upper and lower sideband are not considered ham radio bands. Upper and lower sidebands are part of every single AM transmission. Using those modes is uses a portion of the radio spectrum allocated for that channel, rather than using most of it like AM transmissions. Licensed Amateur Radio operators have no special privileges on CB in the US. Everyone has exactly the same privileges on CB. There have been cases of Amateur Radio licensees being fined for lousy behavior on CB frequencies.

Your description of how an antenna radiates the radio energy is very close, except for one key detail. When you place the antenna feed point at one corner of the vehicle you will pull the major lobe towards the opposite corner of the vehicle from the antenna feed point.

Here is what a radiation pattern would look like for a certain type of antenna...


This is not a CB antenna, but one I want to use to illustrate. You can see the major lobe(its the largest one right in the center). The antenna sends most of its energy in the direction of the major lobe. Picture your jeep in the center that chart.... A base fed antenna in the center of the roof, will have a radiation pattern that has its major lobes along the front and back of the jeep, with much smaller lobes along the sides of the jeep.

The further you move the antenna back on the Jeep, the large you will make the lobe to the front of the jeep, while shrinking the lobe to the rear. This is because you have now changing the length of the ground plane front to rear.

The same idea works side to side on a vehicle....So move the antenna from the center to the passenger side and you stretch the lobe on the drivers side while shrinking the one on the passenger side.

If you are old enough to remember... Highway Patrol cars.. where were their antennas mounted??? Passenger side rear quarter or bumper. Why?? This would cause the major lobe of their radiation to go towards the drivers side front of the car. Why would they do this??? So that their transmission and reception went in front and left of them. So it went further down the highway and covered the other side of the highway.

Like you and I both mentioned. We are always going to be dealing with a series of compromises. The very best antenna is going to be 36 feet long and mounted in the center of the roof. But that isn't possible on a vehicle that is driven. So we have to look at what will resonate the best. 1/2 wave or 18 foot would be another choice, but we can't use that on a vehicle either. So we look at what 9 foot is, 108 inches. This we can do... The whips that are available are generally 102 inches long.... Why??? Because the strain relief springs are normally about 6 inches long. 102 and 6 gives us 108 inches or 9 foot long.

 

I knew i was off on some points. thankyou for clarifying. Just want the correct info getting out there.

 

Awesome my antenna measured out to b the right length with the spring so how do i set the swrs

 

Because they haven't come to realize the FM revolution yet. (My CB went bye-bye a few months ago in my Jeep, did it to my dd a year ago).

Crash course on antennas:
Antennas are resonate at odd 1/4 wave lengths ( 1/4, 3/4, 5/4, etc.). For a quarter wave antenna, there is a 1/4 wave ground (or greater) so it forms a dipole (talking in terms of mobile antennas). The good thing about 1/4 wave antennas, they have roughly a 45º TOA (take off angle) which makes them really good for hilly environments but limits them to fairly short transmit area (TOA has a lot to do with "skipping"). For distance, the 5/8 wave antennas are generally better (lower TOA, signal goes further before skipping, higher gain). 5/8 have to be impedance matched however (usually in the form of loading coils).

Gain:
RF transmit power is measure on a log scale (dB) but most people know of it in the terms of Watts. Long story short, for every +3(dBi) of gain it's roughly the equivalent to doubling power. (You can find the Power in Watts to Power in dB conversion online and run the numbers yourself).

SWR:
Really just a ratio of how much power is being reflected back into the transceiver. Example, a 2:1 ratio at 4W means roughly 2 W is coming back.

Now, I'm not a fan of CB's mainly due to size (the manufacturers haven't really used modern tech in them in a long time) guys who run commercial radios at work know what I'm talking about.

I hopped on the FM boat (practicality reasons actually) and started running VHF and UHF equipment. More power, better quality, and repeaters. I know a few clubs which are actually doing this as well. Not to mention the fact the antennas are way shorter.

This is my dd, but where the commercial UHF radio is mounted on the console was where my CB was mounted in my XJ. That radio is a 45W radio, the HT on top of of the console is a 4W radio…


I run all 5/8 wave antennas (front w/center load is a UHF +6dB antenna, rear is a VHF +3dB antenna) and again this is on the dd (haven't gotten a full replacement radio for the XJ yet so it will either be a 1/4 Wave VHF or a high gain dual band) but I usually throw a 1/4 wave up on it with a Motorola radio.


And again to emphasize what I mean about CB's catching up with technology, my Cobra 25 (4W dk, swing to 12 with my favorite 5/8 wave antenna), a surplus Motorola GM300 (45W circa 1993 with a magnetic 1/4 wave antenna), and an Icom 100S series radio (221S, 45W circa 2008 with a 1/4 wave NMO antenna sitting on top of it).