UHF antennae

Submitted: Thursday, Dec 30, 2021 at 17:43
ThreadID: 143035 Views:8555 Replies:9 FollowUps:13
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Hi all. Just after some opinions (based on your experiences). My current UHF antenna is a GME AE4705 - Big fiberglass thing mounted out at the end of the bullbar. This position is great in that it is not in the field of view really but it is the one position on the bullbar that moves the most when driving over rough road. I bought that antenna after the previous one (other brand) broke somewhere out west. I have wondered about having a different antenna mounted on a bracket at the side of the bonnet. What are peoples' experiences with antennae mounted in the position? What model/make do you use?
Cheers
Suitcase
Prado SX and a little van

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Reply By: RMD - Thursday, Dec 30, 2021 at 18:14

Thursday, Dec 30, 2021 at 18:14
Suitcase.
Mentioned once before, Electric Bug owner in Adelaide advised me a long time ago to throw a bar mounted aerial away. He said, the position is not optimal and mentioned the long white ones are not much good in performance. I had a long aerial on a bull bar but after his advice changed to a bottom loaded with a single heavy wire upper which has it's wire wound as a 3turn coil half way up. It looks like a cylinder with an aerial screwed on top. Mounted on side of roof rack or central on roof rack as it is now, it has performed very well. There is no substitute for up high. Some brackets are available which allow the aerial to liedown rearward so as to minimize any damage from low branches.
I have never considered a big long aerial or out front since.
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Follow Up By: Member - Core420 - Thursday, Dec 30, 2021 at 19:50

Thursday, Dec 30, 2021 at 19:50
I have my GME aerial on a folding bracket on my roof rack. Best performance.
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Reply By: Member - McLaren3030 - Thursday, Dec 30, 2021 at 21:23

Thursday, Dec 30, 2021 at 21:23
The secret to good reception is the antenna and it’s location. Antennas come in various styles, they can be long or short fibreglass broom sticks, or something that resembles a heavy single wire with a “spring” type coil half way up, plus a few others. The choice is yours as to which type you go for.

Antennas are generally designated into three “types”, 9 dbi, 3 dbi, & 6 dbi. Depending on where you spend the most time travelling, will determine which one to get. If in mainly flat areas, a 9 dbi antenna will give you the longest distance. If in hilly terrain, a 3 dbi antenna is generally considered better. If you do both, for a compromise, a 6 dbi is probably the better choice.

There was a good article on unsealed 4x4 regarding UHF Antennas that is worth a read.

I have a 6 dbi GME AE4704B antenna on a spring base matched to my GME XRS Radio.

Macca.
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Reply By: Member - Suitcase (QLD) - Thursday, Dec 30, 2021 at 21:38

Thursday, Dec 30, 2021 at 21:38
Has anyone tried one of these ? Kaon Bracket?
Suitcase
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Follow Up By: Pepper - Friday, Dec 31, 2021 at 06:04

Friday, Dec 31, 2021 at 06:04
looks really good to me..
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Follow Up By: Member - McLaren3030 - Friday, Dec 31, 2021 at 08:27

Friday, Dec 31, 2021 at 08:27
Hi Guys,

Boobook on here has a roof mounted fold down antenna bracket mounted to the roof rack of his vehicle.

Further to my previous post, ideally for best possible reception, the centre of the roof of the vehicle is best, but not always practical. As close to the centreline of the vehicle is best, with the tip above the roof line of the vehicle. You do not necessarily need a 2.0 m long broom stick, just as long as the tip is above the roof line, and the appropriate dbi.

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Follow Up By: Bazooka - Friday, Dec 31, 2021 at 11:21

Friday, Dec 31, 2021 at 11:21
Interesting bracket Suitcase but what happens when you lift the bonnet?

As many have already said highest point centre of vehicle is supposedly best for reception but whether it's best practically is another matter. Mine is currently on left bb bracket on Prado
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Follow Up By: Briste - Friday, Dec 31, 2021 at 21:36

Friday, Dec 31, 2021 at 21:36
I have the Kaon bracket on my Prado. Very impressed. No problems opening the bonnet. Very stable. Can't comment on the efficacy of the location compared to others, but seems to work well.
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Reply By: Member - rocco2010 - Thursday, Dec 30, 2021 at 22:37

Thursday, Dec 30, 2021 at 22:37
Somebody once said nothing vibrates like an ARB bullbar on a Prado and it’s just a matter of when an antenna will break.

Somebody else told me to get a bit of poly pipe of right size and length and slip it over the antenna. This is just a generic Jaycar whip on a GME base.

My bit of tube goes on as soon as I hit the gravel. It stops the antenna whipping about and has survived the worst of the Canning Stock Route when I’d had two breakages on lesser tracks.

It aint fancy but it’s cheap.
AnswerID: 638961

Reply By: Mikee5 - Friday, Dec 31, 2021 at 08:21

Friday, Dec 31, 2021 at 08:21
I have had a GME AE409L stainless skinny wire antenna set to 6db on my bullbar for 13 years now and it has never let me down. Because feedback was that these failed regularly I carry spare parts for it with me but have never needed to fix it. Maybe I am just lucky.
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Follow Up By: Member - McLaren3030 - Friday, Dec 31, 2021 at 08:31

Friday, Dec 31, 2021 at 08:31
A good point Mike, I also carry a spare antenna with me as well, not the same one as is mounted to the Bull bar, but an old one. Mainly to keep communication with other vehicles that I travel with, so don’t necessarily need long distance. It also is a 6 dbi antenna.

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Follow Up By: Member - rocco2010 - Friday, Dec 31, 2021 at 11:57

Friday, Dec 31, 2021 at 11:57
I had a skinny wire antenna on a side bonnet mount on my Ranger.

Lasted a good few years before metal fatigue got it and it broke off.

Again not fancy, but effective and cheap enough so that failure doesn’t reduce one to tears.
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Reply By: Frank P (NSW) - Friday, Dec 31, 2021 at 12:22

Friday, Dec 31, 2021 at 12:22
Mine is a Uniden 6db on a fold-down bracket on the roof. I have an identical spare which I found on a track :-) plus a cheap wire spare that twice I've given to travel mates whose BB mounted aerials have snapped off.



No BB harmonics up there to fatigue the wire and break it and the fold down bracket protects it against low branches. The radiating part of the antenna is above the firewood basket so range is good in all directions and it's ground independent (like most) so doesn't need to be in the middle of the roof.

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Follow Up By: ian.g - Saturday, Jan 01, 2022 at 14:11

Saturday, Jan 01, 2022 at 14:11
Have had this GME mounted on a mudguard bracket on my Colorado, has been there for over 200K without problems, mounted it there because I couldn't stand looking at the dancing bull bar mounted examples that just about everyone else seems to have. No signs of fatigue at this stage
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Reply By: Member - Warren H - Friday, Dec 31, 2021 at 15:32

Friday, Dec 31, 2021 at 15:32
I've a Kilpatrick Communications 6.6dB aerial, simple spring base and fiberglass whip. On heavily corrugated roads it will sometimes develop a standing wave which I figure can't be good. I like rocco2010's idea of the polytube and wonder if hot water pipe foam insulation would do the same job, given you just need to alter or disrupt the harmonic?
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Follow Up By: RMD - Friday, Dec 31, 2021 at 19:59

Friday, Dec 31, 2021 at 19:59
Warren.
While foam tube may dampen the wobbles. I would be careful if it ever got damp as that will alter the SWR of the aerial and possibly not perform well and may cause damage to output transistor of the radio. Radio experts will know more on that.
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Follow Up By: Nomadic Navara - Saturday, Jan 01, 2022 at 12:22

Saturday, Jan 01, 2022 at 12:22
"and may cause damage to output transistor of the radio"

RMD, that is ancient history. Two way radios with transistorised transmitter outputs date from the late 1960s, your statement certainly applied to those radios. However, that problem was designed out of them in the first 20 years of so of production.
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Follow Up By: Frank P (NSW) - Saturday, Jan 01, 2022 at 14:41

Saturday, Jan 01, 2022 at 14:41
I'm glad to hear that, Peter.

Some time ago my roof mounted antenna was stolen. I didn't notice it until I started investigating ridiculously poor performance from a radio that an hour ago was working perfectly. I had been making repeated transmissions and upon the discovery of the missing antenna was worried that I might have damaged the output stage of the UHF. I replaced the antenna with a spare but remained concerned that some damage may have been done, even though the radio worked fine.

I am happy that my concern is ill-founded.
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Follow Up By: RMD - Saturday, Jan 01, 2022 at 15:06

Saturday, Jan 01, 2022 at 15:06
Peter D
Thanks for that info, but what devices are used to switch the transmission frequency if it isn't a solid state device affected by heat? and isn't the full amount of reflected wave an issue in causing heating of the output section?
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Follow Up By: Gronk - Saturday, Jan 01, 2022 at 17:13

Saturday, Jan 01, 2022 at 17:13
Get rid of the spring. The aerial doesn’t dance around anywhere near as much without one.
No breakages in 7 yrs without one, should have done it yrs ago..
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Reply By: Gramps - Sunday, Jan 02, 2022 at 19:38

Sunday, Jan 02, 2022 at 19:38
I have used a Uniden AT880 Twin (6.6/3db) antenna for the last 5 years or so. Mounted on the Cruiser's bullbar it has survived the CSR, ABH, CSH, GCR and Tanami (i.e. plenty of corrugations) without a problem. Range seems fine though I have'nt tried to measure it as such.

Regards
AnswerID: 638976

Reply By: Dean K3 - Tuesday, Jan 11, 2022 at 19:09

Tuesday, Jan 11, 2022 at 19:09
RFI CD 51-68-73 if you can get hold of one if possible roof mount for best reception.

CD51-68-70 is the antenna minus the coax from memory.

Small very light weight won't break unlike steel or very heavy fibreglass styles do.

a few specs:

Whip Material Copper braid element in flexible nylon tubing
Whip Length mm 360
Cable And Connector Not included, order separately. See note (2)
Tuning Field tune to minimum VSWR using supplied tuning chart
Band 450 - 520MHz
Frequency Range 450 - 520
Power w 50
Nominal Gain Dbi 4
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