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Inside antennas & reception

This forum is dedicated to helping people with questions about installing radio equipment in vehicles. This can include antenna installs, electrical wiring questions/problems, and mounting systems. Pictures of installs are welcome.

Note: Discussions regarding lighting, sirens, and other equipment now has its own forum in the 'off-topic' section below.

Moderator: Queue Moderator

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PhillyPhoto
was LuiePL
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What radios do you own?: XTS/XTL5000

Inside antennas & reception

Postby PhillyPhoto » Mon Apr 07, 2014 8:55 am

Looking around all I can really find is RF radiation from antennas mounted inside vehicles. That's not too much of a concern to me as I'll be mostly monitoring. My main question is what kind of loss is there by mounting the antenna inside vs on the trunk or roof? I'm trying to keep this as low-profile as possible because I don't want it to look like a cop car. 1 is UHF and the other is 7/800.
-Luie-

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Bill_G
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Re: Inside antennas & reception

Postby Bill_G » Mon Apr 07, 2014 9:18 am

Depends on the glass. If its heavy tint, it might be copper vapor which turns the car into a Farraday cage.

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PhillyPhoto
was LuiePL
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What radios do you own?: XTS/XTL5000

Re: Inside antennas & reception

Postby PhillyPhoto » Mon Apr 07, 2014 9:57 am

I'm 99% sure this is for the tint I have on my car:

SUN-GARD’s top of the line, non-reflective, color-stable film will stand the test of time. Many car manufacturers are advising that metallized film may interfere with keyless locks, GPS and satellite radio systems. Shadow’s metal free construction makes it the perfect film to avoid signal disruption.


I have the antennas just sitting on the ends of the NMO cables now with no ground-plane and they're picking up signals pretty decently. I'm sure that partially answers my own question, but I wasn't sure if there was a general rule-of-thumb for or against it.
-Luie-

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Bill_G
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Re: Inside antennas & reception

Postby Bill_G » Mon Apr 07, 2014 11:34 am

Well, there you go.

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escomm
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Re: Inside antennas & reception

Postby escomm » Mon Apr 07, 2014 5:10 pm

A paper clip would work

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Bill_G
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Re: Inside antennas & reception

Postby Bill_G » Mon Apr 07, 2014 6:44 pm

12oz pop can will too. Plus it's dual band 450 and 800. Bonus!

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escomm
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Re: Inside antennas & reception

Postby escomm » Mon Apr 07, 2014 7:05 pm

It would work better since the signal would receive on both sides of the wall

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Bill_G
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Re: Inside antennas & reception

Postby Bill_G » Mon Apr 07, 2014 7:38 pm

I used to make them for the local beer distributor. They do lack physical strength, and get a gnarley lean back after going +60 down the highway.

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PhillyPhoto
was LuiePL
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What radios do you own?: XTS/XTL5000

Re: Inside antennas & reception

Postby PhillyPhoto » Tue Apr 08, 2014 5:18 am

What about staples from my red Swingline stapler? They say it never jams, but I had to test it out. Now I have some staples sitting on my desk and I don't know what to do with them.
-Luie-

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Bill_G
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Re: Inside antennas & reception

Postby Bill_G » Tue Apr 08, 2014 5:42 am

Covert antenna disguised as a staple necklace or a dream catcher.

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PhillyPhoto
was LuiePL
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What radios do you own?: XTS/XTL5000

Re: Inside antennas & reception

Postby PhillyPhoto » Tue Apr 08, 2014 6:09 am

Bill_G wrote:Covert antenna disguised as a staple necklace or a dream catcher.

Or a yagi disguised as a Pine tree air freshener.
-Luie-

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Bill_G
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Re: Inside antennas & reception

Postby Bill_G » Tue Apr 08, 2014 10:01 am

Don't laugh. I've had to put radomes on yagis and decorate them with flags so they meet the visual blight standards of a rooftop, and put white plastic cross arms on fiberglass sticks so they look like the crucifixes on Calvary (which actually turned out kind of cool looking). Those third grade skills suddenly came in handy.

KE7JFF
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Re: Inside antennas & reception

Postby KE7JFF » Tue Apr 15, 2014 2:36 pm

Bill_G wrote:Don't laugh. I've had to put radomes on yagis and decorate them with flags so they meet the visual blight standards of a rooftop, and put white plastic cross arms on fiberglass sticks so they look like the crucifixes on Calvary (which actually turned out kind of cool looking). Those third grade skills suddenly came in handy.


I think I have a picture of your grade A skills somewhere then if thats the case...

Back on topic, one of the very small limo companies around here, they had radios installed in their 3-vehicle fleet, which was two limos and a towncar. The towncar was suposed to be the "supervisor car" so it had a MTS2000 convertacom installed in some werid spot by the back seats, but the quarter wave antenna for the covertacom was mounted upside down on U bracket by the back window.
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N4DES
was KS4VT
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What radios do you own?: APX,XTS2500,XTL2500,XTL1500

Re: Inside antennas & reception

Postby N4DES » Fri May 02, 2014 8:42 am

I have had pretty good luck with this for scanner and low power portable usage.
http://www.tessco.com/products/displayP ... ventPage=1

LAX1
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Re: Inside antennas & reception

Postby LAX1 » Tue Jul 29, 2014 7:14 pm

I've 2 Stealth-Inside car antennas. Results were not so good. In one case the glass tint contains some metal which works to detune and attenuate the antenna. The other case had a matching network between the radio and the stealth antenna. The matching network couldn't maintain its tuning with temperature variations and the vehicle bouncing over pot holes plus the insertion loss. Transmit is most critical for a good match. Receive will be most affected by the signal to noise ratio. Best solution is to use a stealthy external antenna.


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