AM/FM Antenna

Submitted: Wednesday, May 07, 2014 at 16:05

ThreadID: 107657 Views:5841 Replies:4 FollowUps:6

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Hootsmon

Hi,
The radio aerial on my 80 series only pokes up about 30cm. When you switch on the aftermarket double din head unit the aerial fully extends then retracts back to 30cm out. I've had the dash off to check wiring and the auto aerial power lead is connected as is amp power. Rather than pay an auto elec to fix it I was going to disconnect the power to keep it down and spend the dosh on a spring mounted am/fm one. It'll be on the bull bar. Reading around the best ones for this are ground independent. Seems to be though the only ones I can find are marine. White plastic without a spring base. Any other suggestions? I know supercheap do a high gain one but not sure if it is ground independent.
Cheers All

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Reply By: bluefella - Wednesday, May 07, 2014 at 16:35

Reply By: Allan B (Member, SunCoast) - Wednesday, May 07, 2014 at 17:43

Wednesday, May 07, 2014 at 17:43

Recent thread 107551 here may be of help to you.

Cheers
Allan

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AnswerID: 532060

Follow Up By: Member - Boo Boo (NSW) - Wednesday, May 07, 2014 at 18:12

Wednesday, May 07, 2014 at 18:12

Allan

Thanks for the info re "mobile one".

I have been looking around for a better antenna for a while, obviously I did not look hard enough.

I am going down to Mittagong for a week in June and will get myself a new antenna while I'm down there.

FollowupID: 815249

Follow Up By: Allan B (Member, SunCoast) - Wednesday, May 07, 2014 at 18:57

Wednesday, May 07, 2014 at 18:57

Hi Boo Boo,
Mine works a treat and is now well away from passing scrub.

Cheers
Allan

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FollowupID: 815256

Follow Up By: Hootsmon - Wednesday, May 07, 2014 at 19:12

Wednesday, May 07, 2014 at 19:12

Yes. Thank you. Mobile one looks the go. Just need to find out if they are ground independent or not. I'm OS at the moment in Bonnie Scotland. Will give them a call on my return.

FollowupID: 815259

Follow Up By: Allan B (Member, SunCoast) - Wednesday, May 07, 2014 at 19:32

Wednesday, May 07, 2014 at 19:32

This is from the Mobile One website:

"Generally speaking the longer the antenna the better the range or distance. In order to achieve the best performance out of a mobile antenna it should be mounted on the highest part of the vehicle and in the case of monopole antennas (i.e.: single whip antennas requiring a ground plane!) they should be as close to the center of the vehicle as possible. This is usually impossible to do on most modern vehicles but this is what to aim for.
The best installation should be, antenna length first, height of the antenna second, then the position of the antenna last."

But not everyone wishes to put a hole in the vehicle roof (as I did) to obtain the advantage of a ground plane.

Good idea to talk to them (0246556677). They are very helpful.

Cheers
Allan

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FollowupID: 815266

Reply By: The Bantam - Wednesday, May 07, 2014 at 22:53

Wednesday, May 07, 2014 at 22:53

You will find very few car radio antennas that are ground independent.....

As far as the need for a ground plane.....having the aerial grounded to a roof rack or a bracket that is grounded to the greater mass of car will be sufficient.

Remember this is recpetion only.

For AM.....no antenna that you can mount on a car will ever be long enough to be resonant....a quarter wave at AM radio frequencies will be a couple of hundred feet.

For FM, it is reasonable to build an aerial that will be properly resonant...the wave length is about 3 meters, thus a 1/4 wave would be about 750mm....still a bit of a chalenge for an efficient & practical ground independent design.

Don't get stuck on this ground independent thing......on UHF ground independedent is the go.....because it is practical at those frequencies....down on VHF is is less practical.

BTW the bullbar is the worst place for any antenna.....best thing is on the side of ya roof rack on a knock down brancket.

cheers

AnswerID: 532081

Follow Up By: Member - Wozikev - Thursday, May 08, 2014 at 15:42

Thursday, May 08, 2014 at 15:42

Hi Bantam,

My phone and UHF are both on the bullbar and are far from ideal. I would like to move them to the rack as you suggest as I'm sure it would be a huge improvement. I would like to mount them centre front of the rack to minimise the risk of tree damage etc. Can you tell me where I can pick up the type of knock-down bracket you refer to.

Cheers ......................... Kev.

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Follow Up By: The Bantam - Thursday, May 08, 2014 at 21:41

Thursday, May 08, 2014 at 21:41

I made my own...its fairly straight forward.

take two short square angle brackets......like 50 x 50x 50.

I did some drilling and tapping and hand filing to make em nice.....but it can be done quick & dirty..still effecive.

you will need to grind the corners on one leg of each bracket to a nice radius concentric will the single hole in these brackets.

put a bolt three washers and a nylock nut thru the two parts.....bolt, washer, angle, washer, angle, washer, nut......when this is all mounted you tighten up the nut till the rig is just tight enough to hold at 110KMH.

You will need to drill out one of the angles to fit your aerial.

easy enough to make...works damn well and costs under $10..plus a little time.

cheers

FollowupID: 815324