Originally Posted by Matthewd5

What good is the cb if you have to take down the antenna when you hit the trails?

Matthew

Originally Posted by hypeiv

From what I have seen on the trail is 75% of Jeep CB's have very bad grounding... Most Jeepers just deal with this and turn the volume on their CB radios all the way up and put up with a bunch of static, the problem comes when someone with a properly grounded CB joins their group and blasts everyone out. If you have to turn your volume over 50% to hear someone less than half a mile away, one or both of your setups is messed up.

a tailgate mount from teraflex or RR will not be enough ground... YOU HAVE TO RUN A GROUND WIRE IF YOU USE THOSE MOUNTS. I was like a lot of people and thought I should give it a try and see if it works... trust me it will not. Even with a ground wire I can only get around 1.3-1.4 SWR. Even at that SWR I have been accuessed of running an illegal amp b/c the other jeeps with incorrect CB set ups were saying I was coming in too loud... the problem was they had their cb's set to full volume so they could hear each other.

CB's are limited to 4w of power, when your SWR gets too far above normal the power is cut to help protect the radio. So low power and bad antenna == no one can hear you.

I have helped people install their cb and one drilled into a steel bumper and the other did the cowl... both set ups absolutely blow away my tailgate mount so I agree with the OP in the ranking of how best to setup the antenna. I will be ditching my tailgate mount when I upgrade to the Teraflex carrier and move my antenna to the cowl.

Edit: if you end up running a ground wire make sure you use a star washer on both ends of the wire... I ran mine from the stud to the bolt next to the sub.

Originally Posted by SiliconTi

I thought I'd try the cowl mounts, so I decided to make metal tabs to mount under the hood and stick out a couple inches, then mount the antennas to these. Great ground, no vertical metal, good ground plane.

WRONG. SWR skyrocketed on both VHF and CB. My old mag mount has 1.1:1 SWR on the cowl, 1.2:1 on the bumper. Now it is over 4:1. CB was similar.

I'll be switching back tomorrow.

Originally Posted by realjeep

Jeep Antenna Placement Recommendations. CB ~27 Mhz, HAM 140-148 440-450 Mhz and Commercial 150-170 450-470 and 800 MHz Frequencies. For low 3 to 7 Mhz HAM antennas I'm not covering that here as those are special antennas and if you have a license for those frequencies then you already know what your doing.

I have been looking around the forum at the descriptions for antenna placements and there is some good advice out there, but not all in one place so I have decided to make an easy English description for those not so tech savvy. Please keep in mind that this post is to describe the best balance of function and looks. Granted putting an antenna in the middle of the hood is a great transmit spot but it's in your field of view and makes the Jeep look like a unicorn.

Background: I am a commercial two-way radio tech with Ham and marine licenses. I have been doing installs for about 18 years. Like police cars, ambulances utility trucks and the like.

Guidelines to follow and these are relative to your situation. For example: if you park your Jeep in the garage you can't put your antennas on the roof rack so the cowl is you next best thing.

Guidelines:

1 The longer the better. (Relative to your situation if you have 5000 foot peaks that have repeaters a small antenna like mine will work fine, but if you need to talk on a simplex/direct frequency the longer the better.)
2 The largest horizontal ground plane the better. A horizontal ground plane is exactly that a flat piece of metal or metal spikes going off in 4 directions from the base of an antenna. (See exception to this guideline later in this post)
3 The farther away from vertical flat metal the better.
4 Keep the antennas separated a foot or even more is better. Keep VHF 150 Mhz away from the stereo antenna. If you using a scanner that does not transmit then that's ok next to the stereo antenna.
5 Avoid Bumper and license plate mounts if possible.
6 DO NOT PUT YOUR ANTENNA BETWEEN THE TAIL GATE AND THE SPARE TIRE
7 DO NOT PUT YOUR ANTENNA BETWEEN THE TAIL GATE AND THE SPARE TIRE
8 Just to make sure you are reading this correctly DO NOT PUT YOUR ANTENNA BETWEEN THE TAIL GATE AND THE SPARE TIRE. Read below for a more detailed explanation on this.

I will put the easy answers here at the top with more detailed explanation at the bottom for those interested. Listed here are the best to worst places to place antennas at the bottom I will also talk about other types of antennas that I don't have images of.

1st On top of the center of a roof. If you never plan on taking off the hard top off then the things you can do are place a large piece of metal under the roof, attach the antenna to a roof rack or get a no-ground plane antenna (guideline # 2 exemption).

2nd On the cowl. Must effective place after the roof and it allows you to have longer antennas and still make it the garage. Also is good for those that don't want to drill holes in their body. I have 5000 foot mountains so I don't need a long antenna.

Seen here is my small dual-band antenna for HAM use.

Note: if you need to place more antennas on the cowl try to avoid VHF 150Mhz near the stereo antenna as transmitting near that antenna will cause noise on your car radio.

3d on the corner of the Jeep. This is preferred over the bumper because it gets the antenna up above the body metal line. You will see the light bar from Olympic in this shot and they advertise it as a place to put antennas. This may be ok as it's away from the body of the Jeep. Seen here is my commercial 800 MHz antenna looks like the one in front but its coil is in a different place.

4th Bumper: You see an Olympic bumper here with a hole for CB antenna This is OK but not Ideal as the base is still below wall of steel on the body. A license plate mount would have the same problem.

5th Between the tailgate and the Spare tire. As I said before DO NOT DO THIS UNLESS ABSOLUTLY NESSARY. AND DEFINITELY NOT FOR HAM OR COMERCIAL FREQS. Besides being the most inefficient place for and antenna one can't open the window and close the tailgate.

More detailed stuff.

The Jeep Wrangler presents us with a problem it's a convertible with no metal roof. Two-way radio antennas weather they be CB, HAM or Commercial need to breathe. I.E. it needs to be exposed to air with as little horizontal metal next to them as possible. It also needs a ground plane under it. Ideally the ground plane should be a diameter equal to ½ of the wavelength of the frequency. So a 150 Mhz antenna would have a diameter of about 38 Inches CB would be about 6 yards NOT TO BE FOUND ON A JEEP.

The nice engineers that make antennas use coils and such to compensate for this. Here is where our unique problem lies these coils need to be exposed to the air and not near horizontal metal as much as possible. Nearly all ham and commercial antennas have coils and they are at the bottom of the antennas. So placing them on the bumper right next to the body will cause the radiation to be reflected back in to the radio which over time will damage the power amplifier in the radio. The cowl and the higher rear corner placement is desired because the roof is made of fiber glass and the radiation will just pass through it. Yes there are pillars and roll bars but the radiation will bend around them verses being reflected back.

The tailgate and spare tire situation yes, I know all our favorite web venders sell tailgate antenna brackets but they should only be used as a last resort. And again I know in caravan style on the trail they work fine and Jeepers have been mounting them there for years but ...

This is why they're bad. Remember the base of the antenna must be exposed as well as the whip. Think of a nuclear bomb going off the gamma rays can't pass through 1 inch of lead or 10 feet of concrete and in our case of two-way radio signals the tailgate and spare tire are acting like a sandwich keeping our radiation inside and not allowing it to escape. I started here just because I thought it was cool looking. However mounting the antenna here proved to be fatal. Basically I had two pieces of large solid metal surrounding my antenna base causing massive reflected power going back into my radio and not radiating out. I used a watt meter to measure what was happening. Some of you out there may have access to something called an SWR meter and that's fine if you know how to use it, it will tell you the same things. I use watt meters because I need to know how much power is coming out of my radios for commercial purposes to satisfy FCC rules. Ideally if you have a 30 watt VHF radio you want 30 watts transmitted out with as little reflected back as possible. 30 watts with say less than 2 reflected is great. I had 25 watts with 20 reflected. The more reflected back will also adversely effect the power out which is why I had the lower number on output. After tuning my antenna to 30 watts with 2 reflected the antenna went from about 50 inches to about 30 inches making it nice long high gain antenna useless. And of course one can't open the back window and close the tailgate without removing the antenna thus making that random trip to the hardware store for 2x4's a bit of a problem without a roof rack.

For those of you who mount your antenna base above the spare tire with an extension there is still the problem of a ground plane unless you use say the Olympic light bar or make a bar of some sort you end up with the same problem. There is an exception to this rule as mentioned in guideline # 2 above and that is a no-ground plan antenna they do exist for CB, HAM operations and radio towers. Of course you could use one on the fiberglass Jeep roof too but then you can't take the top off or get into the garage. Just remember keep the base as well as the whip away from vertical flat metal. Like the tailgate spare tire and body. Pillars and roll bars are ok but try to keep the antenna as far away from them as possible too.

Other antennas that you may have seen or many want to use:

1 On-glass antennas, I have used them but they are not great. They don't have a good ground plane and lots of reflected power. I would avoid if possible.
2 I would also avoid dual-purpose antennas like ones that use the car stereo antenna as a VHF antenna with a splitter box one to your stereo and the other to the Two-Way. Not to be confused with dual-band antennas that's different and used for HAM Frequencies.
3 Side ball mount antennas, used for CB and military frequencies. As long as they are mounted to the highest point on the body the better. You may have seen these long whips that bend down to the front of the Jeeps. This served two purposes that I know of one was so the whips did not hit the trees in the jungles and the other was to make the radio talk shorter distances. See at 100 Mhz the radio waves pass through the atmosphere below that they bounce back to earth commonly known as skip. The whip standing vertical could skip from New Mexico to Louisiana but bent over It could talk from one side of New Mexico to the other. This all of course depends on frequency, power time of day and sun spots.
4 Magnetic antennas, these are good for the temporary weekend trip as long as they attached to a good solid piece of metal. I would not recommend them for permanent mount as usually the coax is put through a window or doorframe and will eventually get damaged.

Here is an image of different radiation patterns. I don't have an image for what it would look like for the tailgate and spare tire but basically the signal isn't going very far. The center image shows the most ideal relatively round even pattern. The corner mounted antenna show what happens when the antenna only has a ground plane on two sides and not 360 degrees.

*** MORE TECHNICAL UPDATE ***

I conducted an experiment using a Commercial grade CB antenna Made by Tram with an NMO mount. I tested it on the Cowl, Rear Corner, Rear bumper and the rear light bracket with an SWR Meter. In the pictures you will see a bulkhead mount that I used. I used one on the light bar with and with out extra radials to see if it would improve the readings. I don't have any "fire stick" style antennas and those may get a lower SWR reading however I believe my experiment shows the basic difference in performance one can achieve on the different locations of the Jeep.

Readings

Cowl SWR 1.2 result Great
Rear Corner SWR 1.5 result Good
Light bar with and without the extra radials SWR ~2.0 result Not the best
Bumper SWR 3+ Result Very Bad.

NMO Bulkhead mount

NMO Bulkhead mount with radials

NMO Bulkhead mount on bumper

NMO Bulkhead mount on bumper

Originally Posted by Abritinboston

Hey realjeep! what kind of antenna is that u have on the cowl? I love how small it is, is that your cb? I'm looking to set up my first cb and think that's a great look!