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Radar Detector

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Broz

New Member
Hello. It's been a long time since I posted anything here. I have been doing some electronics projects and worked my way into micro-controller projects with the help of this forum. I want to learn about something new now. I've done nothing with RF, and I'm wanting to do a few RF projects now. One of the projects has to do with the cheaper radar guns which operate on the K band (10.525 GHz). I want to build a real simple radar detector as an RF project. Yes I know I can buy one, but I want to build one just as a learning experience. I know just the very basics of how RF detection works. I'm hoping it's an easier project as I don't want to communicate with RF yet, I just want to detect it, however, I do not have an O-scope, so I will be doing this blind (which is why I always shy away from RF projects).

Any advice on how to get started?
 

bychon

New Member
Buy a scope!

But seriously, RF is FM to me (f***n magic). Report regularly. I'll be watching.
 

Broz

New Member
Buy a scope!

But seriously, RF is FM to me (f***n magic). Report regularly. I'll be watching.
I wish I could buy a scope. I know there's some cheaper scopes out there, but I really don't have the kind of money to view frequencies such as the K band radar guns.

FM, we used to use that phrase when I worked on radar jamming equipment in the Corps. If something was a mystery, it was FM. :D
 

Boncuk

New Member
I wish I could buy a scope. I know there's some cheaper scopes out there, but I really don't have the kind of money to view frequencies such as the K band radar guns.

FM, we used to use that phrase when I worked on radar jamming equipment in the Corps. If something was a mystery, it was FM. :D
Airborne radar jamming is based on frequencies beyond 10GHz. Target tracking radars normally work close to it, missile tracking tracking radars are not very far away from that frequency band.

Jamming is not the most effective way to fool AA-missiles. Range-gate and azimuth pull-off are much more effective. (Returning the missile to sender if required.)

All you need is a scope displaying frequencies beyond 10GHz.

It'll be settled in the 50,000US$ class.

Boncuk
 

jbeng

Member
The K-band radar antennas that I used to work with had a center frequency of 24.150GHz. The X-band ones were centered at 10.525GHz.

An oscilloscope which could resolve those kind of frequencies would be seriously expensive, if they exist at all.
 

lord loh.

Member
You could use an oscilloscope to view the envelope of the received high frequency signal. Rectify the signal if you find a diode that can handle it (i seriously doubt) and see the rectified-filtered signal. Alternatively, I am sure there are points down the radar gun circuits where the frequencies are lower and can be viewed on a lower bandwidth scope. If you see something expected there, you can be sure that the other parts are working.
 

jbeng

Member
In the systems we made for speed measurement, the only place RF was found was in the microwave section of the antenna. Everything else was audio frequency.

After the transmitted microwaves were reflected by a moving object (usually vehicles or baseballs), a difference signal was generated by mixing a small amount of the transmitted signal (as a reference) with the return signal. This was accomplished by using a Schottky barrier diode (SBD) as a mixer in the microwave cavity. The difference signal coming out of the SBD was an audio frequency signal corresponding to the speed of the object which reflected the microwaves.
 

crutschow

Well-Known Member
Most Helpful Member
Unless you are familiar with microwave circuit design (where you must use micro-strip type PC traces and all circuit dimensions are critical) I would not recommend that as a first RF design project. Stick with something below 100MHz (even for those frequencies, careful layout is required for proper circuit operation).
 
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