CB radio antenna

Good CB radio performance lives or dies by the antenna. The worst antenna, in my opinion, for range and clear transmit / receive signals are the magnetic base type CB antenna's. There is much debate which antenna length is better, 1/4 wave length or a 1/2 wave length. My personal choice would be a 1/2 wave length, but in heavy brush and thick forest trails the longer length of the 1/2 wave length antenna can be a real hassle. Either length antenna 1/4 or 1/2 will need to be tuned for SWR (Standing Wave Ratio). The whole theory for SWR is the get a clean 1/4 or 1/2 length radio wave off the end of the antenna. If the SWR is wrong, antenna to long or short, radio transmission voltage will be feed back into the radio transmitter. The more voltage feed back into a radio transmitter the lower the range and clarity of the CB radio. Most any antenna will do, as long as the SWR is adjusted!
dave
PS sometimes (SWR) is known as VSWR or (Voltage Standing Wave Ratio)

the most effective you can run is a 102in whip with a 8in spring and 18.5 ft of coax. the problem with this setup is it is hard to tune and most 4wd associations have banned them (you do not want to get hit by one). for jeeps i personally like the wilson 5000 trucker. it is a center load with a short stainless whip. these can be mounted on the spare tire rack, are easy to tune, and can handle a fair amount of power.

i would avoid fiberglass whips as they are ineffecient and hard to tune. the one thing to remember for antennas is grounding and location, location, location. high up and in the center of the vehicle is best.

you also need to weigh what you are doing with your radio. i like to talk distances greater than 20 miles and do a little skipshooting. this requires an excellent radio, a little heat (foot warmer, bleedbox, pumphouse ect...) and a very good antenna system (yes system, antenna, mount, coax, grounds).

there is a lot more to consider, and i could go on all night. if you want more info email me.

dan

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I have a simple fiberglass whip, about 4' long, mounted on a Radio Trash / Sack / Shack ball mount and spring drilled thru the rear passenger side corner of the Jeep. I know this is drilling a hole, but it is a clean setup, with the coax protected, and not having to fish it through somewhere.

SWR is difficult to tune with the fiberglass antennas. I have also had good luck with a base loaded metal whip of the radio-shack variety. These are the ones with a coil at the bottom. These are easier to tune for your SWR, as the main whip part can be moved up or down with a small allen screw. A 102" steel whip is nice, but it's a PITA on a tight trail with trees - this is where it hits people flying around - I can't see using one on a trail Jeep.

I'm a mechanical guy, but here is how I understand it:

As was described, SWR is your standing wave ratio. It is the ratio of "power sent out by the radio" divided by the "power that is radiated by the antenna". Ideally, you want this to be 1:1. As in, all of the power sent out by the radio is radiated by the antenna. This is seldom the case. Antennas are set up for a certain frequency. If your radio goes from 26.965 Mhz (channel 1) to 27.405 Mhz., (channel 40), your antenna needs to be tuned to work somewhat OK on all these frequnecies. You will get the best signal out with a 1:1 "match", or SWR. Usually, I try to get this on channel 20, and then it will drift a little on 40 or 1. You would like to see the match below 1.5:1 at all times. If it gets over 3:1 your radio can be damaged, as the power it is sending out is not getting radiated by the antenna, and is going right back into the radio, supposedly, heating it up and causing bad things. As you go further away from 1:1, your output signal drops.

Basically, an SWR meter can be had a Radio Shack, and you connect it between the radio and the antenna. Set it on "set" or "Ref." (there is a switch on it that usually says "Set" or "Ref." on one side, and "Forward" or something like that on the other.). Key the mic with the meter on set, and line it up to a ref mark on the meter. Then, switch it over to the other way, and key the mic again. 1:1 is usually where the needle doesn't move, and it will go up to whatever your match is.

From a ground-plane standpoint, the position of your antenna can matter on your signal propogation. A van has a great advantage here. An antenna in the middle of the roof on a van will propogate the signal good in all directions. Mine, at the rear passenger side of the Jeep, gets out good to the front and the left, but not so well to the rear or the right. If you put it say on your spare tire carrier dead center, you would get out good to the front, but lousy to the back.

Not sure all of this is spot-on, but it is my understanding

Good luck
Pete

88YJ,4"susp,33"BFGMT,9kwinch,homemade swingout,258,999,4.10,weber32/36,GMHEI,one moonguy/wwwthreads_images/icons/smile.gif

While all these discussions about SWR and ground planes are valid, I think the original poster has probably been overwhelmed. Since the original question was posted in a 4x4 board, you probably have much the same constraints as the rest of us and you probably want to use it on the trail like most of the rest of us. This means the antenna may encounter tree branches and other brush. It also means you'll normally be talking to other vehicles that are relatively near by.

To keep it simple, go with a fiberglass whip type of antenna in either a 3 or 4 foot length. Mount it where ever most other people with your type of vehicle do. Get the SWR tuned. Enjoy. If I've made correct assumpions about your intended use, this will be more than adequate.

I have a 4' Wilson Silverload antenna. It's thinner and flexes a lot more than most other fiberglass antennas so I have no worries about driving under tree branches. It cost around $20. I mounted it on the spare tire bump stop on the right rear corner of my Jeep Wrangler. You can get brackets that bolt onto the bumpstop but I chose to get an aftermarket bumpstop with a solid top and then drill a holl through the top to mount the antenna. This gave me a cleaner installation.

One other comment. 4 watts is the legal output power limit for CB. But most CB shops I know of will "tune up" a radio to put out more power for $10-$15. This does help. Of course, my radio does NOT put out 20 watts. ;-)

I purchased a Steel Horse spare tire bumpstop from one of the mail order shops (about $12 I think). It's made out of aluminum and is closed on the top (as opposed to the stock bumpstop which has an open top). I also purchased an antenna mount (I think that's what you call it). It's a short cylindrical piece that the antenna threads into and which electrically isolates the antenna from the vehicle. The manufacturer name for the mount was VanOrt and any CB should should carry these types of mounts. I drilled a hole in the top of the bumpstop, inserted the mount into the hole and then threaded the nut onto the mount from underneath the bumpstop. The antenna threads into the top of the mount and the coax threads onto the bottom of the mount underneath the bumpstop. The coax I bought has threaded connectors at each end so I didn't need to by those pieces and a crimper tool assemble them.

I routed the coax into the vehicle through the opening behind the right rear taillight. Many people do this but pinch the coax. I took a small file and notched out the bottom edge of the taillight housing enough to fit the coax in but not enough to create a hole all the way through the plastic. I then drilled a hole through the top of the right rear fender well as far back and out of the way as possible. I made the hole large enough to accomodate a rubber grommet in addition to the coax. The coax enters my Jeep there and snakes along the top of the right rear fender, down along side the roll bar, under the passenger side door opening and up under the dash to where I mounted the radio. Since I have carpet in my Jeep, the coax is mostly hidden.

Once you've installed you radio and antenna, you should have the SWR tuned. If you buy all your stuff from a CB shop, they ought to do the SWR for free (my opinion - your mileage may vary).

By the way, I got my radio, antenna, mount and coax from Bronco One here in Phoenix.

Good luck.