On glass mount uhf cb antenna

Submitted: Thursday, Aug 28, 2014 at 16:26
ThreadID: 109304 Views:10526 Replies:5 FollowUps:4
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How good are GME AE5002 on glass mount uhf cb antena's ? Or would my 5w hand held using the stumpy antenna from inside the car be as good?

Paul
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Reply By: Ross M - Thursday, Aug 28, 2014 at 16:54

Thursday, Aug 28, 2014 at 16:54
Paul
Do you mean "through" the glass?
It does work but there must be a loss involved.

Why not a external aerial/magnetic base and coax to inside for a dash unit or handheld with an adapter?

Inside, the handheld may project forward OK, but the vehicle body will shield much of the side and rearward transmission.
AnswerID: 538265

Reply By: The Bantam - Thursday, Aug 28, 2014 at 18:19

Thursday, Aug 28, 2014 at 18:19
look at the specifications..gain figures don't lie....well not much.

If the particular aerial produces more than 2dbi, that means it will be better than a dipole and many on radio aerials.

remember on the top of the screen it will be much higher and clearer than the radio inside the car.




The gme aerial you mention lists 2.1dbi......which is equavalent to a plain quarter wave whip on a ground plane..like the AE4002...more or less unity gain compared to a dipole.

not fantastic, but probably better than a bare handed radio inside a tin box with some holes cut in it

cheers
AnswerID: 538273

Reply By: Robin Miller - Thursday, Aug 28, 2014 at 19:06

Thursday, Aug 28, 2014 at 19:06
Its relatively ineffective Paul, depending on how you hold the HH.

The best thing you can do is mount HH in a phone type holder where its aerial can see thru the cars windows and use a seperate mic which allows you to keep your hands off the HH and not distort its radiation field.
(good thing to do with a phone as well if using it with a bluetooth connection)

When using the on glass device you lose 1/2 you signal up front then a bit more in cable and then a bit more as usually you can't mount the on glass vertical.

Note there are 2 types of on glass , one that is on glass sort of like a see through stick on transfer which stays on inside and a 2nd type which is tranformer coupled thru the glass to a vertical rod on the outside.





Robin Miller

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Follow Up By: The Bantam - Thursday, Aug 28, 2014 at 22:35

Thursday, Aug 28, 2014 at 22:35
sorry robin the specs simply do not reflect your assertions.

If you lost half the power ( that is minus 3db) thru the on glass a half wave on glass aerial would have a gain of -1dbi.......they don't...the aerial in question and others spec up similar to a base mounted 1/4 wave.

good on glass antennas, the coupling is pretty damn efficient.

The main drawback is thet mounts are not strong enough to support the heavier high gain sticks

If an on glass areial specs up as having a gain of 2.1dbi.....that is equavalent to a 1/4 wave areial on a ground plane.

At 400 Mhz..cable loss is not great over the lengths involved..even with the small coaxes used.

if mounting the onglass on the top left hand corner of the windscreen.....most vehicles there is no problem at all getting the aerial vertical.

An onglass is never going to compete with a good 6.5dbi colinear...but it will work...amd probaly way better than the aerial on the hand held.

cheers
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Follow Up By: Robin Miller - Friday, Aug 29, 2014 at 08:00

Friday, Aug 29, 2014 at 08:00
You have been taken in by the spin Bantam - the 2.1 is an approximate theoretical dipole gain , they do not measure and publish the gain of the whole antenna and feedline.

Robin Miller

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Follow Up By: The Bantam - Friday, Aug 29, 2014 at 21:01

Friday, Aug 29, 2014 at 21:01
The reputable suppliers most certainly DO measure the whole antenna.

They will as a matter of course " zero out" the feed line.

Oh yess indeed some of the lesser manufacturers work off theoretical figures or figures derived from the antenna they are coppying.

The good on glass...or should I say more correctly.."thru glass" systems are quite efficent...particularly in a certain frequency range.

There may be some loss....but nowhere near "half the power" or 3db.

fair enough there may be loss in the feed line...but there is always loss in a feed line regardles of the aerial in question.

in light 3mm coax like RG174 the losses can be reasonably high ..like 3db in 5 meters.
in the common more or less normal 5mm RG58 the losses are half that about 1.5 DB in 5 meters.

So...if the thru galss system will connect with RG58 in place of the very light stuiff often used it is worth using it if possible.

and within reason keep the cable short.

cheers
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Reply By: Member - P and JM - Thursday, Aug 28, 2014 at 20:59

Thursday, Aug 28, 2014 at 20:59
Hi Paul,

I have been using an "On Glass Antenna" for VHF for years and they perform well as long as setup on the glass is done correctly.
They usually have a trimmer capacitor on them so you can adjust the VSWR to perfection.

When buying make sure you can purchase replacement double sided tapes for the antenna so you put on another vehicle at a latter date.

Good luck and cheers P&J
AnswerID: 538283

Follow Up By: The Bantam - Thursday, Aug 28, 2014 at 22:36

Thursday, Aug 28, 2014 at 22:36
Most of the UHF aerials will require no tuning.

cheers
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Reply By: Freshstart - Friday, Aug 29, 2014 at 09:36

Friday, Aug 29, 2014 at 09:36
May I suggest that, as mentioned above, you get either an external antenna for the hand held, a 6Db is best all rounder would be a good start, or best of all get a no thrills and simple proper transceiver and install it in the car with an external antenna.

Keep the hand held for directing a recovery or when parking a van etc. It's more effective saying "NO! the other left you twit" over a radio.

I have never heard of a through the glass antenna performing anywhere near satisfactory nor as good as an external antenna. The claim above is a first for me in 40 years radios. But I suppose there is always the exception.

For us, we wouldn't use the through glass system as we consider the CB as part of our emergency kit and thus wouldn't compromise.
AnswerID: 538302

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