Why is an alarm system with radar sensor + warning not approved in the StVO?

Hello, So I have a little problem … I have installed a hifi system for several thousand euros and I like to leave a navigator or a laptop in the car – don’t see it at all why I should change my habits because of a stray. But now it’s the case that I was already broken into and yesterday when I went to my car I saw a parasite with its nose glued to my disc … probably has probed the “location”. In order to scare off such rattles from the front (before the disk is hit) I came across a 2 zone radar sensor, which in addition to the interior also monitors a few centimeters around the car. If one “too close” starts a pre-alarm. Unfortunately I had to find that such a radar sensor “not in the stvo” is approved with Voralam. Why is that so?Do you have other ideas as I can protect my property from this specific clientel? adar sensors not allowed? What penalties do I expect if I still install such a sensor? Is there legal alternative? Something you have to do! A very hot candidate with me would be http://www.ampire.de/security/ampire/508a.html Julianchen…who has a right to retain her property!