UHF Antenna's

I'm a little confused with what $ you pay for different types of antenna's and the brands and specs.

Every dealer / seller says there's is the best etc.

My requirements are multi use--coverage :- needs to be long range on trips and short range around the mountains where I live..also need to consider ease of removal when in the city due to theft? I imagine.
I have a bull bar with the necessary mounting points--3 in total

anyone have any advice and or experience in this decision ?

thanks
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Reply By: bigfut - Wednesday, Feb 17, 2010 at 07:16

Wednesday, Feb 17, 2010 at 07:16
I had similar requirements to you, and ended up purchasing the set listed below on the website link. Came with the two aerials (3db and 6db) which makes it easy to select the right aerial, and always means you have a spare in the car if something happens.
DSE Aerial
AnswerID: 404515

Reply By: Member - John and Val - Wednesday, Feb 17, 2010 at 07:17

Wednesday, Feb 17, 2010 at 07:17
Gazza,

The cheapest ones are not very robust, but are functional.

The gain of the aerial can be important. Low gain (4.5 dB) doesn't have the range of higher gain aerials, but high gain (9 dB) tend to transmit largely in the "horizontal" plane so can be unsatisfactory in hilly country where the vehicle isn't always horizontal. Probably the best compromise is a 6 dB aerial.

I use a 6/9 dB aerial by GME and find that the 9 dB configuration is fragile (metal fatigue on corrugations) and in open country doesn't help much with range over the 6 dB.

Another factor to consider is whether a ground independent aerial is preferable. It's probably desirable if mounting on the bullbar, as it should perform a bit better than one that isn't independent.

My pick would be a 6 dB ground independent.

HTH

John

J and V
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AnswerID: 404516

Follow Up By: olcoolone - Wednesday, Feb 17, 2010 at 08:55

Wednesday, Feb 17, 2010 at 08:55
Agree 100%, the GME 6/9 kit is what we use and have never had a problem.

We only use the 6dB section.

The 6dB offers the best of both worlds, good on short range hilly stuff and good on open country flat stuff.

Some people become very pedantic when it comes to UHF antennas and gain.......they will try and buy a 3.45293465dB antenna because it might work 1% better in an area they travel twice a year over a 4db.

The difference in gains make very little difference in the REAL WORLD.

The way some people talk about dB gain sounds like all they do when traveling is change antennas or worry about it (is this antenna optimised for the range I want and the terrain I'm driving through...or could it be better.).

If you get an antenna from GME, RFI or Laser in the 4 to 6dB range that is ground independent you will be more then happy and have a good antenna.

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Follow Up By: Member - John and Val - Wednesday, Feb 17, 2010 at 13:22

Wednesday, Feb 17, 2010 at 13:22
Gazza,

It's GME's AE409L we are talking about. Effectively it is a kit of 2 aerials that use a common base. If one gets broken, you still have a spare. The only problem I've encountered was on horrible corrugations where a standing wave (mechanical) build up in the bigger 9 dB aerial, which eventually broke off and disappeared overboard. Took a couple of minutes to install the 6 dB spare. Since then I provide a plastic "splint" to support the aerial proper and get rid of vibrations. Not elegent but works well.

John
J and V
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Follow Up By: DesF - Wednesday, Feb 17, 2010 at 15:09

Wednesday, Feb 17, 2010 at 15:09
Hi Gotta agree with the AE409L, have had one for about 10years and it has been on 3 different 4x4's all mounted on the bars,
I only use the 6db , have tried the 9db when up north , but only seemed to get better signal when other 4x4's,are in the same plain/ valley as you,once there is a hill between you not as good as the 6db, also as they have said they do a fair dance when rough,
Touch wood! have not broken one yet, I have two bases as a chap bought one and it was too tall to go under his carport so he just kept cutting some off untill it did, so I got a new base and about 10 pieces off ariel for nix,
Cheers Des.
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Follow Up By: Shaker - Wednesday, Feb 17, 2010 at 15:39

Wednesday, Feb 17, 2010 at 15:39
AE409L is hopeless on corrugated roads.

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Follow Up By: DesF - Wednesday, Feb 17, 2010 at 15:45

Wednesday, Feb 17, 2010 at 15:45
Never worried it on two Subaru's and on the Pajero, admit have not been on the canning as such but the dash has been a blur plenty of times,
Can only mention ones own experiences,
Cheers Des
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Follow Up By: olcoolone - Wednesday, Feb 17, 2010 at 22:15

Wednesday, Feb 17, 2010 at 22:15
Never had an issue with many thousands of Kilometers of corrugations and extremely rutted tracks.

Used this type of antenna on other vehicles with no damage.
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FollowupID: 674328

Follow Up By: Shaker - Wednesday, Feb 17, 2010 at 23:15

Wednesday, Feb 17, 2010 at 23:15
Well, the author of the reply that you have just followed up to, also had one break, so my problem wasn't an isolated case.
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Reply By: GerryP - Wednesday, Feb 17, 2010 at 08:41

Wednesday, Feb 17, 2010 at 08:41
Hi Gazza,

Went through a similar thing a few years ago. I ended up moving the antenna to the roof and using a $13 quarter wave (short) flexible rubber aerial. Best reception I ever got, great in built up areas, very good over reasonable distance and pretty much indestructable. And... no one wants to pinch it.

Moving from the bull bar to the roof, I think, has made the major difference.

Cheers
Gerry
AnswerID: 404522

Follow Up By: DIO - Wednesday, Feb 17, 2010 at 08:51

Wednesday, Feb 17, 2010 at 08:51
Yes I agree. For most use i.e. convoy etc a small antenna as you've stated is more than adequate. A lot cheaper too.
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Follow Up By: Member - Phil G (SA) - Wednesday, Feb 17, 2010 at 14:37

Wednesday, Feb 17, 2010 at 14:37
I'm with you Gerry.
For 95% of my travel, I use the short rubber roof aerial. If anyone has problems getting one, Electric Bug have them.
http://www.electricbug.com.au/product/90
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Reply By: Shaker - Wednesday, Feb 17, 2010 at 09:48

Wednesday, Feb 17, 2010 at 09:48
I live on the edge of the High Country & also do a lot of Outback travel, I ahve found that a 4.5db antenna is ideal & use a GME AE4705.
AnswerID: 404534

Reply By: Member - Mike DID - Wednesday, Feb 17, 2010 at 11:16

Wednesday, Feb 17, 2010 at 11:16
For Bullbar mounting, it MUST be the Ground Plane Independant type of antenna.
AnswerID: 404541

Reply By: vk1dx - Wednesday, Feb 17, 2010 at 12:51

Wednesday, Feb 17, 2010 at 12:51
Just get the 9Db one and be done with it. Its not worth trying to improve a system that is not designed to work in hilly areas. So do the best for where the antennas are going to do the best - on the flats or when you are close.

The bull bar is one of the worst places you can mount the antenna. The best is in the middle of the roof. But we put racks up there and thats where it may get damaged from trees. So we end up back at the bull bar. Its all a compromise.

UHF won't bend around corners or up and over hills so we have to rely on reflections and refracted signals. Another compromise. Rain, hail, rees, shrubs and the ground condition will attenuate the signal again.

Practically speaking the range is as far as you can see plus a bit. It wont bend over the horizon except if the ground is a perfect conductor.

Not a pretty picture is it.

Thats why I say get a 9Db one and mount it as close to the center of mass of the car and as far as practical from any oither antenna or metalic object, where it is safe from damage and not sticking in pedestrians eyes and not in your direct line of sight.

Mostly practice soldering the antenna lead to the connector before doiung the final soldering. This is where most make mistakes. Just don't stick it in and think that is it. Its worth getting a good tech to do it and then best if he/she has done a soldering course. You have to make sure the impedance is not mucked up with a bad joint.

Phil
AnswerID: 404548

Follow Up By: StormyKnight - Wednesday, Feb 17, 2010 at 18:48

Wednesday, Feb 17, 2010 at 18:48
Phil the issue with a 9db in hilly country is that you may have line of site to the other car, but if they are not close to being perpendicular to your aerial they will not have very good reception at all. As you move up & down the signal transmission (shaped like a squash donut with 9db) will fade in & out quite noticeably.

Also of note is the gain of your aerial also effects reception....two cars with 9db aerials will have a lot more interrupted conversation than two with 6db aerials in hilly country.

Cheers


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Follow Up By: vk1dx - Wednesday, Feb 17, 2010 at 19:14

Wednesday, Feb 17, 2010 at 19:14
Exactly and that is also why a higher angled propogaion will not help much. Yes the lesser gain ones are slightly better but is it worth it. Cahnging antennas every time they are not parallel or when you go from the hills to the plains. Because of this and that UHF is not really ideal for any mobile comms I suggest not to wast too much effort in trying to improve it.

I could go on about radiation patterns etc etc and all the tech work but its not worth it.

Just get the 9db and set the antenna up as best you acn.

Phil
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Follow Up By: Member - Roachie (SA) - Thursday, Feb 18, 2010 at 21:06

Thursday, Feb 18, 2010 at 21:06
Can I be so bold as to suggest that the vast majority of 4 wheel drivers use their UHF for intra-convoy comms? As such, it is not normally an issue (in wide open flat country), that comms are disrupted, regardless of whether the vehicles are fitted with a 4.5db, 6db or 9db antenna.

On the other hand, as Stormy Knight has pointed out, a 9db antenna in the high country, can have severe limitations.

As such, I am of the opinion that a "compromise" antenna of either 4.5 or 6db is the best option.... Leave the "broomstick" in the kitchen.... hahahaha. They are only for "wenk value".

Roachie
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Follow Up By: vk1dx - Thursday, Feb 18, 2010 at 21:14

Thursday, Feb 18, 2010 at 21:14
Whatever
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Follow Up By: vk1dx - Thursday, Feb 18, 2010 at 21:59

Thursday, Feb 18, 2010 at 21:59
Question

How on earth do I stop the postings on a thread coming to me in an email?? I cannot find it the FAQs and my message to "contact us" has not been answered.
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Follow Up By: Skippy In The GU - Friday, Feb 19, 2010 at 08:47

Friday, Feb 19, 2010 at 08:47
I have seen 1/4 wave mounted on the centre of the roof worked just as well as a 6 or 9db on the bullbar.

Also when traveling above 80kph the 9db will lean back because of the wind and won't work as well then when stationary
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Follow Up By: vk1dx - Friday, Feb 19, 2010 at 12:23

Friday, Feb 19, 2010 at 12:23
Hi Skippy

I hope you haven't got a roof rack around that antenna.

Also my 9Db doesn't bend, even at 100K. I just went into town for a blood test and took note of what you said.

So I gather you have one of those stainless steel whips or its broken. Maybe the spring mont is the wrong type.

Phil
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FollowupID: 674600

Reply By: StormyKnight - Wednesday, Feb 17, 2010 at 18:57

Wednesday, Feb 17, 2010 at 18:57
Other than reception transmission range there are a few other things to remember...

Some aerials are not recommended for Diesels.......yes its true. The vibration when idling will be enough to weaken the aerial and snap it off (generally at the base). These aerials are generally the single thick wire type without a spring base.

Having an aerial on the bull bar is not the best for transmission or reception. A ground independent aerial will help with that. The other advantage of the location is that as a driver you can see the aerial & see what its going to hit. This brings me to the last point...

A 4.5db aerial will be shorter than a 9db. The bigger the aerial the more likely is it will hit something....even your garage door!

One more thing, often the aerial will be a fixed aerial & lead combination, especially if its ground independent. If you need to replace the aerial, you will need to replace the lead too. It is possible to get a lead & base, fit a ground independent adapter & then the aerial of your choice (or perhaps just a ground independent aerial), that way if you need to change the aerial, is nice & easy.

Cheers
AnswerID: 404596

Reply By: gazza414 - Thursday, Feb 18, 2010 at 08:28

Thursday, Feb 18, 2010 at 08:28
thanks very folks, much appreciate the input. it has helped a great deal..nothing like being armed with some background info before taking the plunge and regretting the decision due to lack of info

thx
AnswerID: 404695

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