Compliments of Firestik Antenna Company Technical Support Team
Copyright 2005 Firestik Antenna Company
This article pertains to Jeep utility type vehicles (TJ, CJ, Wrangler, Rubicon, etc.). Since most Jeep installs involve ground plane dependent antennas, that is the focus of this article. Even though no-ground-plane (NGP) antenna systems can be used on a Jeep, there is sufficient ground plane available on most (if not all) Jeeps which makes a standard ground plane dependent antenna the most reasonable choice.
Installing a CB antenna (or other transmitting antenna) and then using the transmitter without first testing and/or tuning the antenna system is a dangerous proposal. Unintentional shorts or high SWR can damage the radios circuitry. You can listen with a bad or untuned antenna system but you should never attempt to transmit until the SWR is tested and known to be in a safe range. If you are new to CB antenna installations, we strongly recommend that you read the three articles that are found in this TechHelp section under "SWR Testing and Setting".
There are four popular ways for mounting CB antennas on Jeeps.
- Bumper Mount
- Spare Tire Carrier Mount
- Tub Mount
- Front Fender Channel Mount
1. Bumper Mount
- The three main concerns with a bumper mount are strength, grounding and minimum antenna length.
- You must be absolutely sure that the bumper, and the mount, has a good chassis ground.
- You must make sure that the mount has the ability to support the chosen antenna.
- The minimum antenna length for bumper mount installations is 4-feet. If choosing to use the minimum length, we recommend the FireFly antenna as its winding configuration is more tolerant of parallel interference from soft-tops and fiberglass hard-tops.
2. Spare Tire Carrier Mounting
- If mounting to the spare tire carrier, you should install the mount as high up on the assembly as possible to eliminate parallel side-reflection of the carrier wave.
- If using a base-loaded antenna you should make sure that the mount is the highest object on the tire carrier assemble in order that the most active portion of the antenna can operate with total free-space around it.
- If using a top-loaded (wire-wound) antenna you should strive to have at least the top half of the antenna above the roof line, especially when utilizing a hardtop
- If it is a swing-a-way tire carrier we suggest that a dedicated ground wire from a known good chassis ground point to the antenna mount is used. Swing-a-ways with nylon bushings insulate the carrier from chassis ground and those with brass bushings go through periods of high resistance or total lack of grounding on rough terrain.
- Beware of painted and/or powder coated surfaces they do not conduct. Mounts on those surfaces must either have metal to metal contact with the grounded swing arm or use an alternate chassis grounding wire.
- If you do not want to ground the carrier and/or antenna mount, you will need to use a no-ground plane (NGP) antenna system.
- Soft-top or no-top vehicles get best performance from antennas that are 3-feet and over in length. Those with hardtops should use at minimum, a 3-foot antenna with a spring (for added height) or a 4-foot antenna.
3. Tub Mount
- The most popular location for a tub mount is either above the drivers side taillight assembly, either with a common L-bracket (see our SS-64) or a bracket that mounts directly behind the tail light assembly.
- Mounts on the side of the tub are exposed to foreign objects which can, and often do, dislodged the mount from the tub while causing damage.
- If using a "behind the taillight assembly" mount, be aware that powder coating is an insulator. The mount MUST be grounded when using standard ground plane dependent CB antennas. We recommend uncoated stainless steel brackets but if you use a powder coated bracket, you MUST make sure that the bracket has a good chassis ground and that the coax, either directly or through the antenna stud mount, obtains a ground via the mount. The lack of chassis ground, as explained, will hamper your ability to tune the antenna system and lead to poor performance.
- The factory bolts that hold the taillight assembly to the tub are quite small so we recommend the use of a lightweight FireFly antenna on those mounts to reduce stress. Unless you have the means to "beef-up" the mounting bolts, you need to be very aware of the size and weight of the antenna used.
- Using a common L-bracket (see our SS-64) above the taillight assembly is very popular. It is our preferred type of installation. The taillight lens is removed to access the housing mount screws. With the assembly temporarily removed, there is access to the inside of the tub surface to secure the bracket. We also suggest using the clamping bracket supplied in our 3-way mounts on the inside of the tub for added strength and support.
4. Front Fender Channel Mount
- Fender channel mounts (see our model SS-J4 and mini-kit model MK-J4R) should be mounted close to one of the fender mounting bolts. Older model Jeeps had a support near the door edge and allowed the mount to be positioned closer to the windshield. However, the newer models do not have that support and therefore we recommend that the mount be positioned further forward near the first fender mounting bolt.
- On vehicles that are being used regularly in rough terrain, we recommend the light-weight FireFly antenna and or the base loaded whip type antennas such as our E-36 Venice.
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