A Radar Module Teardown And Measuring Fan Speed The Hard Way

If you have even the slightest interest in microwave electronics and radar, you’re in for a treat. The Signal Path is back with another video, and this one covers the internals of a simple 24-GHz radar module along with some experiments that we found fascinating.

The radar module that [Shahriar] works with in the video below is a CDM324 that can be picked up for a couple of bucks from the usual sources. As such it contains a lot of lessons in value engineering and designing to a price point, and the teardown reveals that it contains but a single active device. [Shahriar] walks us through the layout of the circuit, pointing out such fascinating bits as capacitors with no dielectric, butterfly stubs acting as bias tees, and a rat-race coupler that’s used as a mixer. The flip side of the PCB has two arrays of beam-forming patch antennas, one for transmit and one for receive. After a few simple tests to show that the center frequency of the module is highly variable, he does a neat test using gimbals made of servos to sweep the signal across azimuth and elevation while pointing at a receiving horn antenna. This shows the asymmetrical nature of the beam-forming array. He finishes up by measuring the speed of a computer fan using the module, which has some interesting possibilities in data security as well as a few practical applications.

Even though [Shahriar]’s video tend to the longish side, he makes every second count by packing in a lot of material. He also makes complex topics very approachable, like what’s inside a million-dollar oscilloscope or diagnosing a wonky 14-GHz spectrum analyzer.

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