THP Semifinalist: A Continuous Wave Radar

There aren’t many Hackaday Prize entries playing around in RF, save for the handful of projects using off the shelf radio modules. That’s a little surprising to us, considering radio is one of the domains where garage-based tinkerers have always been very active. [Luke] is bucking the trend with a FM continuous wave radar, to be used in experiments with autonomous aircraft, altitude finding, and synthetic aperture radar imaging.

[Luke]’s radar operates around 5.8-6 GHz, and is supposed to be an introduction to microwave electronics. It’s an extremely modular system built around a few VCOs, mixers, and amplifiers from Hittite, all connected with coax.

So far, [Luke] has all his modules put together, a great pair of cans for the antennas, everything confirmed as working on his scope, and a lot of commits to his git repo.

You can check out [Luke]’s demo video is available below.


SpaceWrencherThe project featured in this post is a quarterfinalist in The Hackaday Prize.

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Making a 9GHz doppler radar

[Kalle] is currently building an FMCW radar, but as he doesn’t have all the parts finished he decided to build a 9GHZ doppler radar in the mean time. The H-plane horn antennas were made from brass sheet and soldered together. [Kalle] checked the matching between the emitter and the antenna by inserting a directional coupler between the two and measuring the intensity of the reflected signal (approximated return loss). At 9Ghz, the Doppler shift for a 1 meter per second speed is about 30Hz so he connected the radar’s output signal to his soundcard.

A quick explanation of the Doppler effect that a radar uses: if you send an RF signal at a given frequency to a moving target, the reflected signal’s frequency will be shifted. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during the approach, it is identical at the instant of passing by, and it is lower during the recession. Hackaday featured plenty of projects using this effect: a small doppler motion sensor, gesture control using doppler shift, hacking an old radar gun