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Antenna for Radar Detector

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WG1337

New Member
Hi!
I got a radar detector, gladly didn't buy it, and got a problem - it doesn't work.
Well I know why - windshield! It is protected with some kind of a layer, that doesn't allow radiation in from the sun and maybe something more.
And of course it doesn't let in radio waves from police radars.
So I thought a simple solution - get a radar detector with an external antenna, but that was a problem, because there were no such things.
As far as I know then these detectors are like radios - they have an antenna and they make a sound when they find a radio wave and the laser detector isn't much different - it uses a diode to detect light (I think).
So if it is quite that simple, then why there are no external antennas for these radar detectors (there are no models from any vendor that would support it)?
And maybe I could make it outside - add wires and glue it somewhere...
I know for Wi-Fi's there are special coaxial cables that allows to move the antenna, sadly I don't know if it works.
 

Sceadwian

Banned
What is the coating on the windshield you think is b locking the radar? There are only a few windshields on a few models of cars which can block radar.
 
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WG1337

New Member
It is blocking. I tried it with an automatic door (laser), windows closed it had no beep, soon as I opened my window - gone crazy.
I don't know what coating it is, but I have Mercedes-Benz W220 S500. Other devices don't work because of the windshield, like remote control for gate etc.
The window coating doesn't block radars, it blocks signals to get in the car, not blocking every single radio wave, GSM seems to work, but barely.
 

Sceadwian

Banned
It's probably a heated windshield so it's actually conductive. As far as remote antenna's go I doubt there common so few cars have windshields like this it's not something they design for typically. You could take it apart put an RF connector on it and use a remote cable but I have no idea what type of coax you would use.
 

WG1337

New Member
I took apart the radar detector.
It actually very small, as far as I understand then the antenna is at the back and uses about 1/2 of the whole chip.
Sadly there are no 2 wires that could be the antenna, but is soldered together on the chip.
I will try to remove the antenna and figure out a way to connect essential connections with long wires, I don't see other ways to make this antenna external.
But yeah, windshield doesn't let radar signals in, I tested it with 2 different radar detectors.
I guess adding a cola can on a wire connected to the antenna won't help :p

Oh, the car does have an antenna for GSM, it is used for the phone that is connected with a wire, actually it always have a very good connection, almost all the time, but I have no idea where it is connected and how it is connected and I wouldn't want to take it apart.
 
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JimB

Super Moderator
Most Helpful Member
Sadly there are no 2 wires that could be the antenna, but is soldered together on the chip.
I will try to remove the antenna and figure out a way to connect essential connections with long wires, I don't see other ways to make this antenna external.
I guess adding a cola can on a wire connected to the antenna won't help :p
The radar uses frequencies up around 9 or 10 Ghz, thats 10,000 Mhz. At that frequency "long wires" are going to have a lot of loss, you will not succeed in this venture, I promise you!

The reason you dont find any radar detectors with an external antenna connector is because of the cable loss.

Coax cable which may be OK at 10Ghz is type LDF 4-50 which has an attenuation of about 12dB per 100ft at 10Ghz.
(Just looked at the LDF4-50 spec again and it is only rated to 8.8Ghz.)
Assuming a short routing between the detector in the car and antenna at the front of the car, say 10ft, that will give an attenuation of 1.2dB, thats not too bad.

However, LDF4-50 is 16mm dameter and very stiff, and has a minimum bend radius of 125mm. It is also very expensive, as are the connectors, You may find some offcuts for £5 - 10 per metre and used connectors for £10 each.

JimB
 

WG1337

New Member
The other idea I had was to move the monitor and speaker away.
Monitor has 2+3 wires and speaker as usual - 2, that could be even more possible.
But like you said, a great loss, I thought about that and I assumed that as the reason why there are no extendable (lol, why google chrome doesn't recognize this word?) antennas.
Thanks for the help!
 

Sceadwian

Banned
Moving the display and the speaker sounds possible, the speaker isn't going to mind a little bit of a longer cable, the display might be not necesarily, what kind of display is it?
 

WG1337

New Member
I don't know what kind are there...
But I think it is a very simple one, it has a small LED behind and at the front only uses a letter shape.
Not a good picture, but this one: Whistler Laser/Radar Detector Features - Model 1743
But the number seems different, it is similar to the way calculators show up numbers.
Model number for the display doesn't seem to be valid: LGM-326YEGYXE-10!
 

Sceadwian

Banned
The picture shows enough. You can run that almost as far as you want without problems.
 

Sceadwian

Banned
If you DO have problems, come back and make me eat my words and I'll do my best to help you fix them =)
 

Sig239

Member
I took apart a radar detector about 15 yrs ago, and it had a forward facing feedhorn to pick up the radar.
 
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