V940 mod

[merrok45]

I while back I saw a thread were someone added an extended horn made out of cardboard and tinfoil on an 8500 and said there was a noticeable improvement. There also seemed to be improvement in sensitivity when the plastic screen was removed from in front of the antenna. Do you think removing the plastic from the front of a 940 and making a little extension might help with the sensitivity?

[<<JAZZY>>]

I while back I saw a thread were someone added an extended horn made out of cardboard and tinfoil on an 8500 and said there was a noticeable improvement. There also seemed to be improvement in sensitivity when the plastic screen was removed from in front of the antenna. Do you think removing the plastic from the front of a 940 and making a little extension might help with the sensitivity?

It might help your long range detection, but it will make it have tunnel vision (crappy off-axis) and suck at cops shooting radar from an angle.

[€]

... but it will make it have tunnel vision (crappy off-axis) and suck at cops shooting radar from an angle.

I made several horm extensions and absolutely can't confirm this!

Unless you overdo the size and horn extension will give not more than 12 dB gain, increased sensitivity and improved detection will be performed in all conditions and in any case. And I have a lot of experience with European safety cameras angled to the road, with the result that the signal hits antenna almost exclusively reflected and off-axis.

My advise - try it yourself

[Sandman76]

12db gain is still a 16X overall performance gain!!!

3db= 2X gain over previous reading.
6db= 4X
9db= 8X
12db= 16X

[€]

12db gain is still a 16X overall performance gain!!!

3db= 2X gain over previous reading.
6db= 4X
9db= 8X
12db= 16X

Not exactly. This what you wrote is just energy (sensitivity) gain. But energy decreases the square of the distance, so it looks like this:

3dBm = 2X sensitivity = 1.4X detection distance
6dBm = 4X sensitivity = 2.0X detection distance
9dBm = 8X sensitivity = 2.8X detection distance
12dB = 16X sensitivity = 4.0X detection distance

And in real world it's even more complicated, since in road conditions electromagnetic field is usually not regular, and in addition there is an influence of terrain conditions, and even the characteristics of individual detectors, such as reaction time (in response to these irregularities).

However, still think it's worth a try

[michael_gourlay]

I made several horm extensions and absolutely can't confirm this!

This intrigues me. Any chance you could share a picture of what the finished product looks like?

[€]

Sure

3-3.jpgX50E_monster_horn_1.jpgFILE0015.jpgMount003.jpg

Here is small pic-manual how I build it:

Horn_Manual.jpg

And a whole thread: http://www.radardetector.net/forums/...l=1#post690469

[nano]

I had a horn extension for my M4 remote antenna (975R). Detection increased about 40&#37;, off-axis was worse than the V1 but not worse compared to no extension.

The "protoype" horn extension for my Whistler wasn't such a great success. I don't know about the exact numbers, but I guess ~20%. Unfortunately I didn't further the development, because I got bored.

[Sandman76]

12db gain is still a 16X overall performance gain!!!

3db= 2X gain over previous reading.
6db= 4X
9db= 8X
12db= 16X

Not exactly. This what you wrote is just energy (sensitivity) gain. But energy decreases the square of the distance, so it looks like this:

3dBm = 2X sensitivity = 1.4X detection distance
6dBm = 4X sensitivity = 2.0X detection distance
9dBm = 8X sensitivity = 2.8X detection distance
12dB = 16X sensitivity = 4.0X detection distance

And in real world it's even more complicated, since in road conditions electromagnetic field is usually not regular, and in addition there is an influence of terrain conditions, and even the characteristics of individual detectors, such as reaction time (in response to these irregularities).

However, still think it's worth a try

Ahhh yes, forgot about the square root because of the distance increase. I was thinking in terms of audio where 3db is 2X the previous measurement but that's at a constent distance.

[BingoPlayerz]

Just curious why one would want to do this to a nice detector. Are you rich? The old V940 is a stellar performer so why would one want to risk destruction for a mere sensitivity gain? The concept aesthetically looks awful, though you are probably not going for looks if you're asking. Also, this slightly practical horn modification still will not defeat IO/QT, but at least no one will steal you detector since it will look so ridiculous. You could also use some more practical materials such as thin brass or aluminum rather than a milk carton and aluminum foil. Theoretically, as stated before LOS or "straight forward facing" sensitivity will increase but off axis and obstruction reflection will be degraded. Doesn't seem worth it, not to a V940 anyways.