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Post Info TOPIC: Glass Mount Aerial for CB
LLD


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Glass Mount Aerial for CB


Anyone use one of these?

Antenna Link

I have a hand held CB that really only reaches vehicle in line of sight. Would like to use an aerial with it.



-- Edited by LLD on Wednesday 14th of November 2018 01:12:55 PM

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Have similar on our Sprinter Campervan, ours is 70cm high and I think the gain may be a bit more, your link show the gain is 1.5DB, others on ebay suggest 2.1 db.

Since we do not have a Bull Bar and I did not want to have the Bonnet bracket to mount a normal CB aerial, what I have is better than nothing.

Peter

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Chief one feather

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Do they have the same cover as the whip style fitted to bull bars etc?

Good idea though.

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No idea if the thru glass ones are effective, or not. It is likely not as good as a proper coax connection. But in any case, 1.5dB gain is plenty for vehicle to vehicle transmission.
Higher gain will give longer transmission, but be less reliable.
I use the little rubber zero or 0.5 gain units for best quality transmission (and they cost less than a quarter of that one). There is no way I want to hear everyone for a 30km radius.
They are all essentially "line of sight", even the very high gain ones.
The most important thing with any antennae is to mount it as high as possible. Even at the top of the windscreen, it is likely to produce a shadow behind the vehicle because of the caravan.
Cheers,
Peter



-- Edited by Peter_n_Margaret on Wednesday 14th of November 2018 07:01:12 PM

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A roof mount magnetic base will be a lot more efficient at CB (477MHz) than a capacitive glass mount antenna.



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Not wishing to derail the thread

But...

Would this type of antenna be any good

https://www.ebay.com.au/itm/UHF-Radio-Antenna-2-1DB-150MM-Whip-Short-Flexible-Aerial-For-Oricom-Uniden-GME/323469536078?hash=item4b50496b4e:g:oGwAAOSwvdxbrD61

It is a screw on aerial, for a hand held CB @ 2.1 DB

Also I have one question

Will increasing the DB of a hand held radio aerial, increase clarity, or just increase the range

Edit as I forgot to say that I notice the EBay seller has 100% positive feedback, so I will assume that he does not sell rubbish



-- Edited by Tony Bev on Wednesday 14th of November 2018 07:24:03 PM

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LLD


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The gain is actually 2.1 - the fine print shows 2.1DBi gain = 1.5db.

I looked at external mounts but that means I have to thread the wiring into the car cabin somehow. After issues with my daughters CB setup, not sure I want to do that.

With a roof mount magnetic base what's the easiest way to get cable into the cabin?

Good point about being in the shadow of the van.

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I understand that the AE4018 is GMEs most popular fibreglass whip aerial at 640mm and 6.x Db gain.

I had a bigger aerial on my Bullbar with more gain, but it had an argument with a tree, now have a cheaper/shorter aerial on the roof of the cruiser.


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Tony, that antennae will not help much unless you are sitting on the roof :)
"Will increasing the DB of a hand held radio aerial, increase clarity, or just increase the range"
As I said earlier, increased gain may increase range (depending on terrain), but will definitely reduce quality of transmission.
Cheers,
Peter

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LLD


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Tony.

Not derailing the thread. Other other suggestion very welcome. I'll look further into your suggestion. No idea on what you get by increasing except that have a look at coverage of various DBs in the GME flyer. Looks like it may be coverage.

www.gme.net.au/media/2689390/landantennarange_b_web.pdf

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Peter_n_Margaret wrote:

Tony, that antennae will not help much unless you are sitting on the roof :)
"Will increasing the DB of a hand held radio aerial, increase clarity, or just increase the range"
As I said earlier, increased gain may increase range (depending on terrain), but will definitely reduce quality of transmission.
Cheers,
Peter


 Thanks for that Peter. it is appreciated.

I had obviously misread/misinterpreted your post
I had assumed that you had meant, that the clarity would decrease, the further away it was picking up the signal

Like you, I am not concerned about listening to people 30 kilometres away
My fear, (with my hearing), is that I may not be able to distinguish, between a person 500 metres away, and one 20 kilometres away

I have a 0.5 (half) watt hand held
I can hear people, without seeing anyone on the road, in front or behind me
The boss makes me turn off the squawk box, as she calls it, when we are in a built up area, or duel carriageway



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Tony

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Tony, the 0.5W power of that hand held will definitely reduce the range and the quality, but it is probably OK for close range communication (especially in front, lesser to the rear).
Better performance all round will be achieved with a 5W unit, or much better again if you can fit an external antennae high up to that unit you have.
Cheers,
Peter

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Thanks, Peter, and LLD

You have both given me food for thought

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Tony

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PeterInSa wrote:

Have similar on our Sprinter Campervan, ours is 70cm high and I think the gain may be a bit more, your link show the gain is 1.5DB, others on ebay suggest 2.1 db.

Since we do not have a Bull Bar and I did not want to have the Bonnet bracket to mount a normal CB aerial, what I have is better than nothing.


 Peter, without denigrating your vehicle, it does not have much of a bonnet, does it? If you mount an antenna down there its radiation to the rear will be blocked and you will effectively only get any good radiation to the front. We used the through the glass antennas a bit when mobile phones were first introduced. We found that metal mounted antennas were superior so the through the glass ones fell out of favour. Even though your antenna is not the best it will outperform an excellent model mounted down on the bonnet. The section of the antenna projecting above the roof will give you better radiation to the rear. The only way you can get better performance is to mount a 2.2 dB antenna on the roof.



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LLD , have you actually checked to see if the antenna is removable on your handheld ?
0.5w units tend to be on the cheaper end of the scale and don't always have a removable antenna.

If that's all a go, make sure you look closely at the antenna socket / plug. It's likely to be an SMA but some radios are female and some are male, which means you will need to pick the correct antenna to fit it.

Those window antennas do work but won't be as good as a roof mounted unit.
That said, it's going to work better than using the HT in the car.
To be honest, don't get caught up in gain on your antenna.
For your 0.5w and the area of coverage, it's not going to make squat difference as compared to getting the signal on the outside of the vehicle which the window mount will do for you.
Also whilst your half a watt may not get you very far, any improvement will also allow you to hear signals from further away and sometimes that's a benefit in itself.

cheers Brett



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LLD


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Brett.

My handheld is a Wireless Pacific GTR 5W. I used in on my motorbike using bluetooth to the helmet. The aerial screws out. I checked the height of the window attachment on the rear of my Ranger XLT and it barely rises above the roof. Trying to see where the wiring from the tub enters the cabin so I can attach a proper antenna to the rear rack and feed the wire into the cabin. I can see the wires but cannot see clearly where the enter the cabin. The Colorado is a piece of cake but the Ranger is not as obvious.

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I've got a mate who has a ranger and is also a ham, so his car looks like a porcupine like mine. I've a feeling he ran all of his out through the firewall though and up the windscreen.

I'll hit him up and see if he can offer any advice on your wiring situation at the back.
I'll get back to you

cheers Brett


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LLD


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denmonkey wrote:

I've got a mate who has a ranger and is also a ham, so his car looks like a porcupine like mine. I've a feeling he ran all of his out through the firewall though and up the windscreen.

I'll hit him up and see if he can offer any advice on your wiring situation at the back.
I'll get back to you

cheers Brett


Called van aerial disease.

My daughter had aerials on the front bull bar and wiring up thru the firewall. I want to avoid that. Had it put in professionally but muggins had to remove it when her vehicle was sold. Been trying today to find out where the equipment went.



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Long time ham here....

Glass mount antennas are a heavily compromised antenna. I use one with the understanding that there can be huge losses in the system - both receive and transmit. While transmitting more than half of your power can be lost. If you have a 0.5W transmitter you'll likely only be radiating around 0.1 or 0.2W and at 5W you'll only be radiating around 1 or 2W. Receive losses are of a similar magnitude.

Antenna gain is usually expressed as x.x dBi and generally the higher the number the better. A full discussion of antenna gain is well outside the purview of this forum but there is a wealth of material available - google "antenna gain" for a bewildering number of articles.



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markf wrote:

Antenna gain is usually expressed as x.x dBi and generally the higher the number the better. A full discussion of antenna gain is well outside the purview of this forum but there is a wealth of material available - google "antenna gain" for a bewildering number of articles.


 I would argue that higher gain is usually not better for vehicle mounted CBs.

The link provided by LLD clearly demonstrates this with the pic of the 2 vehicles in undulating country showing that the lower gain antennae gets a good reception and the higher gain antennae gets none. This is also my experience and I choose to use low gain antennaes on a day to day basis, but carry a high gain antennae for emergency use only (in flat terrain). I have never needed to use it.

https://www.gme.net.au/media/2689390/landantennarange_b_web.pdf

Cheers,

Peter



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that's because of the angle of radiation Pete rather than the gain, albeit that the 2 a directly linked in this instance.

As an example, I had a higher gain antenna on the front bar and moved over to a lower gain unit on the roof.
The difference was night and day.
This is because I talk into repeaters which are set up high on mountains and if I'm talking simplex, I'm often in around buildings too.
So the radiation pattern of the low gain antenna works well.
If you're out covering large flat open plains, then a higher gain antenna with a lower radiation angle would see better results.
Swings and round abouts really.

Get it as in the open as you can and as high as you can.
The CB band isn't for covering massive distances. If you're getting a few kms out of it, that's usually enough.
Regardless of which option is taken, anything is going to work better than sitting with a handheld in the car.






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