Uses for the HB100 Doppler Radar Module 10GHz Experiments.

The HB100 module is intended for use as a Doppler radar motion sensor, e.g. for door openers. Could be used as a primitive speed meter, like the speeding detectors used by the traffic police.

The price of the module itself is somewhere around $3

After testing that the modules with the tuning screw could be tuned down to about 10300MHz without serious degradation of the signal, I can now see several uses of the module, some already described by others.

Here is preliminary list (other uses may be added):

1) simple 10GHz signal generator, using the module as it is, with its PCB patch antenna, tuned to a specific frequency. See also the previous post on this blog where I tested the usefulness myself.
A signal generator for 10GHz for $3.

2) Simple 10GHz WBFM (wideband FM) or FM-ATV TX, using the module as it is, but modulating the power supply. A relatively simple modulator/power supply on PCB (or experimental board) is needed. Some people have already tried this, and a Google search will reveal several ways to generate the modulation.
The modulator could probably be made for $5-10.

3) Simple RX down converter for WBFM and FM-ATV, using the module as it is, and adding a receiver at the IF port. Poor sensitivity, so very short range as the module is.
If used as receive converter only, the TX signal should be terminated in 50 ohm or similar in place of being connected to the TX patch antennas.
$3 and a bit of work.

4) Simple down converter for spectrum analyzer/frequency counter. Using the module as in (3), with the IF port connected to Analyzer/Counter.
$3

5) Very simple WBFM transceiver for *very short range* communication, using the module as is, with a modulator and an inexpensive 80-108MHz FM receiver, Chinese module, can be purchased as a simple kit for around $3, and a cheap audio amplifier, also an inexpensive Chinese module.
I estimate that the complete transceiver could be made for about $25, depending on the  external circuits used

5a) The very simple transceiver can, most likely, be enhanced by a low gain "preamplifier" between the IF output of the module and the FM receiver.

5b) Some experimentation with mounting the HB100 inside a "horn antenna", using the module's patch antennas as "illuminators".

5c) The simple TRX can, of course, be mounted in or near the focal plane of a dish antenna.

6) I have a defective HB100 (No oscillation, and high power consumption, most probably due to reversed polarity of the power supply). Experimentation should be done to see, if it can be used as an up converter with a local oscillator suited for narrow band transverters.
A simple test would be trying to insert a low level RF signal at the IF port of a functioning HB100, and check the resulting spectrum radiated from the RX patch.

6a) The mixer could also be used as an RX down converter mixer, in the receive chain of a NB transverter

It should be noted that  the very simple WBFM TRX, or the module used as a simple down converter, has poor RX sensitivity, due to the loss in the passive mixer.
However, some people have made QSOs up to 200km LOS (line of sight) when using parabolic dish antennas, interesting what can be done with just a few mW. True QRP with extremely simple and inexpensive equipment.
Some experimentation with a TV-LNB followed by a WBFM RX, would probably result in enhancing the sensitivity by 10dB or more.

I can see that the is room for experimentation, and I need to try out some of the above ideas.

If you can think of other uses for the HB100, feel free to comment.