differences in UHF antennas of same gain

[stray dingo]

In my last vehicle I had a the UHF antenna mounted on the bullbar, with a GME sprung base and interchangeable 6db and 2db whip type antennas. I simply bought those cos I was new to UHF and just got something to do the job.

On D4 I need to start from scratch with everything, so trying to make a few better choices in all accessories.

What I don't understand though is what benefit (if any) the different types of antennas have - eg a black tuned GI whippy to a white fibreglass GI rod type when dBd/dBi, impedance, power etc is all the same, and the different lengths in antennas (950mm vs 1130mm).

Is it just aesthetics, and environmental practicality (bush/brush/tree damage) or does one have better performance values than the other in specific situation?
Is the difference in length only to suit an effective mounting height (eg bullbar low in NSW vs top of bullbar loop)

Thanks
Andrew

[goingbush]

have a look here

Mobile One UHF CB Antennas (http://www.mobileone.com.au/antennas/cb477.html)

Good info explains the different antennas

I like RF 470 ground plane independent antennas,
the disadvantage being that you cant easily remove it from the bulbar when not required, You can unscrew the whip but the Silver 1/4 wave tube stays.

I use a short whip on mine, good for a few K's which is all you need on the road, carry a longer whip for more range & a sat phone if it gets nasty.

If you like taking photos out the window the black antennas seem less intrusive to me.

[Disco Muppet]

Anybody know what the really long, wire thin whips the cop cars have are used for?
Obviously they have the longish fibreglass one on the back which i'd assume would be for the computer, so im guessing the long thin ones are CB.
Anyone know the brand of them?
Cheers
Muppet

[THE BOOGER]

Muppet in your area the long thin ones are most likey hf the only ones that may have a cb are hwy patrol

[clubagreenie]

Just went through two days of trauma researching antennas.

Pay attention to how the gain is listed. They use two different types, dbi & dbd.
dbi = dbd + 2.15
dbd = dbi - 2.15

I got a GME TX3520 remote face unit with a AE4705 antenna, 6dbi/4.5dbd so good middle of the road.. HD spring base, fibreglass antenna 1200mm long + another 100 or so for spring. Interchangeable with any other 4700 series antenna plus 4401, 409L & 4013. So you can range from 2.1 dbi to 8.1 plus there's a 9 available as well. Simple screw on and grub screw retainer.

Was $199 for whip, lead and spring, additional whip (say 9dbi for outback) about $130-.

[stray dingo]

thanks Club, but *why* did you choose fibreglass over the whip?

[Graeme]

I like RF 470 ground plane independent antennas,
the disadvantage being that you cant easily remove it from the bulbar when not required, You can unscrew the whip but the Silver 1/4 wave tube stays.

I have an RFI CD900 series which looks to be equivalent to the RF470 series. I had always thought the riser was just that, but like the RF470, the riser provides the ground independence. I have a 5/16" mount on the roof of my D4 for just the whip (when required) to avoid the extra height so perhaps I'm loosing performance although I suspect the roof would be providing a reasonable ground.

[clubagreenie]

The whips by reports and recommendations give better performance. Plus I'm willing to sacrifice one per year damage for what's a reasonable cost vs what is a fairly fragile unit. Length is also a factor in performance and the fibreglass has batter stability at longer lengths. If the aerial is moving then the transmissions are being sent off in unstable directions.

Also the steel wire units either bend and become useless or break off at the base and same. Same for the lighter braided fibreglass, they snap and thats it. With the heavier radome antennas if the glass is fractured then the wire isn't as affected so taped back together is should still work or be useable.

Trust me, I've already forgotten more than I knew before I was taught.