UHF radio aerial
Submitted: Thursday, Aug 22, 2002 at 00:00
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michelle
We are having a GME tx 3400 radio installed next week and I was hoping to get some advice as to the aerial that would suit us best (around Oz with a bit of outback travel). Some are suggesting the really tall aerials for better coverage whilst some have suggested shorter ones (price range around $140-$260) and I think I have read about some where you buy the base and can then change the aerials - or do they all do this? Can anyone recommend which would be the best way to go - an actual product code or detailed description of the product would be fantastic. I have heard people mention that it is much better to put the aerial on the roof - can you attach these to your roof racks somehow? Thanks
Reply By: Member - Nigel - Thursday, Aug 22, 2002 at 00:00
Thursday, Aug 22, 2002 at 00:00
The GME AE4700 range of antennas allows you to swap between short (4.5dB) and tall (6 dB) antennas. These are ground plane independent so can be mounted anywhere, although if you intend to swap to the tall one then the bullbar would be the safest place to mount it.
Otherwise the taller high gain (6 dB or more) antennas are better in flat country and the lower gain (usually 4.5 db) are more effective in hilly country. To get an even signal in all directions I'd always recommend getting a ground plane independent antenna.
The higher you can mount an antenna the better, but often you have to consider car parks, etc hence most antennas end up on the bullbar. Also that makes wiring simpler as no holes need to be drilled. If you are putting the antenna on the roofrack then don't under any circumstances, have the coax just go through the door as the kink in the coax will remove any advantage the extra height would have given. If you go for a roofrack mounted antenna then you must have a hole drilled so that the coax can be run smoothly.
AnswerID:
5900
Reply By: Darian - Thursday, Aug 22, 2002 at 00:00
Thursday, Aug 22, 2002 at 00:00
M......AE409L seems the best - is modular - can shorten or lengthen to suit varying conditions...being GME, it would be tailored to your radio choice anyway. As mentioned above, shorties work best in hilly terrain, and long ones go out further in flat country (but only if vertical - the signal mainly runs 90 degrees to the vertical wire, so if it flops around while mobile, you signal will swing up and down). Centre of the roof is the go for everything, but most of us compromise on location, to suit practicalities. Various bases available for the mounting options. Give it a run !
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5901
Follow Up By: Dion - Thursday, Aug 22, 2002 at 00:00
Thursday, Aug 22, 2002 at 00:00
The GME 409L also fits into the 4700 series base, which is very handy.
Cheers,
Dion.
FollowupID:
2572
Reply By: Burnie M - Saturday, Aug 24, 2002 at 00:00
Saturday, Aug 24, 2002 at 00:00
A ground independant aerial is best.
RFI, Mobile One, Benelec all make an aerial with approx 8 inch 'ground' base with a 2 foot whip screwed on.
Note do not purchase the wire whip, get the thicker fibreglass core whip as the wire whips fatigue and snap near the base.
These aerials variously claim 4-5-6db gain and should cost approx $75.
Mounting;
Assuming damage from bush is not an issue, mount as high as possible (on roof rack?) and away from other metal objects.
Think about mounting on a bullbar (personal crusade);
do you really want to be calling for help in a situation where your mounting point (and aerial) may be seriously damaged ?
Cheers,
Burnie M
AnswerID:
5996
Follow Up By: Member - Nigel - Saturday, Aug 24, 2002 at 00:00
Saturday, Aug 24, 2002 at 00:00
True the stainless whips do break (
mine hasn't yet in 3 years with regularly offroading), but they do transmit a better signal than the fibreglass whips. On the other hand the braid used in the fibreglass whips makes them better at receiving signals.
For when
mine does break I keep a 1/4 wave (about 13 cm long) unity gain antenna in the back of the glovebox, which I can screw onto my elevated feed base until I get a new whip.
I also use a 4.5 dB fibreglass UHF antenna for broadcast FM radio receiption (works better than anything else I've tried) so I've got that as a spare too if needed.
BTW - mines not mounted on the bullbar :)
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Follow Up By: Burnie M - Saturday, Aug 24, 2002 at 00:00
Saturday, Aug 24, 2002 at 00:00
The 2 foot fibreglass whips at about $20 for a replacement with the 13cm (5 inch) ones about $14.
Did a comparison between my RFI 8 inch ground base with a 13cm whip (brand unknown from bleep Smith) and
a Mobile One unity gain 30 cm (12 inch) ground independent (short coil mounded into the lower aerial);
The cheaper Mobile One 30 cm produced more sensitive receive and better transmit reports ie the short unity gain whip noticably reduced the range.
The 2 foot whip on my RFI base was better than both.
Cheers,
Burnie M
FollowupID:
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Follow Up By: Burnie M - Saturday, Aug 24, 2002 at 00:00
Saturday, Aug 24, 2002 at 00:00
To the Fourm Manager;
Don't you think it is very silly to 'bleep' the D I C K in bleep Smith ?
FollowupID:
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