CB antennas...What do I need to know?

[tmanto02]

I'm going to be getting a CB radio next week. I'm planning on mounting it on the spare tyre carrier, as I like the minimal look.

I bought the mounting bracket on ebay, now just to buy the actual radio and antenna.

It'll just be used for talking with mates when we're off roading together. Will the antenna that comes in uniden packs suffice?




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[hpcoolahan]

Yep , the antenna in the pack will be fine mate.

[Rocket55]

RFI, that's all you need to know.

[NTRubicon]

A decent 5W handheld with an external mic should suffice for short medium range, line-of-sight communications. If you're looking to communicate over longer distances (>5km) you may need to set up an installed system in your vehicle.

I have a GME setup with a universal base to swap antennas between a 2.1dB (better for hilly country) and 6.6dB antenna (better for distance) depending on the type of trip I'm doing. My next purchase will be a decent 3-5W handheld for external communications, as the 0.5-2W handheld units are a bit limited for my uses.

[Nanook]

Most people get a bit carried away with aerials and what is required etc.

As already mentioned here, most communication you do in a 4WD is with people that are within line of sight or immediately in front or behind your own vehicle.

What comes in the box is fine for 99% of what you'd use it for.

Grab yourself a cheap handheld unit as well to keep in the cab. You'd be surprised at how handy they are.

[Banshee]

I have a stubby on a mount on the tyre carrier and have nevver had any problems being heard, even on the freeway.

"Higher gain" antennas flatten the radiation pattern from a sphere towards a disk. In short, the higher gain ones are 'better' in flatter areas, lower are better in hills where you may be facing up or down hill & trying to talk to someone who is 'above' or 'below' the plane of your antenna.

The short antenna on the high mount at the back also means it doesn't hit everything when I drive into carparks. (Unlike the 1.5m whip I had ~30 years ago for my 27MHz CB. It hit everything! )

[MightyMouse]

Antenna's are a compromise...... bigger antenna's with higher gains will have a flatter radiation pattern which can give you longer range in flat terrain but can be less useful in hilly country. On the other hand stubby antennas work well in the hills but have a low gain and are shorter range.

The standard supplied antenna is usually 6db which IMHO is a good all around figure. With the frequencies used by UHF CB's, line of sight is pretty much the limit no matter what.

Where you mount the antenna on the vehicle also makes a difference. Central, high and away form other vertical metal is best but in a 4WD its always a compromise.

The ins and outs of antennas are complex......... but in practice using commercial products makes it pretty easy to get good results.