cb aerial

Hi,

Going off knowledge that I haven't used in a while, so I may be corrected but, generally the height of the aerial relates to the dB gain of the aerial, the higher the aerial the higher the dB number (normally between 3 and 9dB?).

The higher the dB number the longer distance it is useful for but is not suitable for hilly terrain.

The lower the dB number the shorter the distance but more suitable in hilly terrain.


So it depends on where you are going to determine what you need.

One of GME 6DB aerials are a good allround aerial. I use a GME AE4705 aerial
Cheers Dave

Hello,

If the aerial is to be mounted on the bull bar, then go for a Ground Independent aerial. A 6dB gain aerial is generally OK. 9 and 12 dB gain is strictly for flat country (they also get very expensive from there). Since we live in hilly country, I have a 3dB gain aerial which I have on one of my 40 series. That actually out-performs a friend's UHF which has a 6dB aerial. Remember, the higher the dB gain the narrower the angle of radiation.

Of course, the best place for a Ground Dependent aerial is in the middle of the roof (also the highest place), but not many people are keen enough to starting boring holes in the roof. So mounting on the corner of the bonnet is usually the best place. This is my preferred option because you are effectively using the bonnet as a ground plane, thus not having to purchase Ground Independent aerials. Also the bull bar is subject to vibration (being an outer extremity of the vehicle) which can destroy aerials. Aerials fitted with a spring-base will overcome this problem.

There are many places to go to when it comes to choosing antennas, GME is a good place to start. GME products are considered to be probably the best.

I have grown fond of the little 4.5dB gain stainless steel antenna whips (Ground Dependent) because they are cheap and very flexible.

Anyway, good luck.

Tim.

Hi Dags,

My thoughts are that its horses for courses to which aerial is the best. A lower gain is good for hilly country whilst a higher gain is better for flatter terrain. The higher an aerial is effects how far you can transmit/receive on flatter terrain (it sees higher over the horizon).

I use a AE4018k GME and it is good in most situations. Some are better in flatter or hilly terrain but this one works ok in most and its only 900mm high.

Cheers Wilko

Dags,

If size is no drama, then give Access Electronics in Rockhampton a ring(07 49221 058) and enquire about their 6dB whip. Best I've seen for Rx & Tx, but are 6' long, similar to one in photo.(though it is an old Antenna Agencies unit, maybe 8 yr old)

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2 others I'd recommend would be Polar 6dB extended gain, or Benelec elevated feed, also 6dB. They are both about 900mm, have spring bases, and the antenna section is easily replaced if it breaks. Priced arond $130 or bit more. They are similar to GME 4018 mentioned above. Both give good results for their size.

From my experience, if you are traversing a lot of rough, or corrugated roads, give the stainless steel whips a miss - they fatigue, and snap off. Also the GME interchangeable antennas, don't like rough roads, and soon detune. so if these light your fire, would suggest to carry a spare.
Haven't found that 9, or 12 dB antennas do much, they are usually too big to have in the bush, or in servo's, and parking stations.

Bob.

thanks alot everyone. at least this points me in the right direction
Dags