‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, January 31, 2020 9:03 AM, jim bell <jdb10987@yahoo.com> wrote:
...

I don't know how they do this,  Is it some sort of mini-phased-array radar?


yup, phased arrays and (less) expensive signal processing.

see also: millimeter wave imaging,
 synthetic aperture radar,
  synthetic aperture imaging.

best regards,

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E.g.:
https://www.electronicspecifier.com/products/frequency-control/duo-offer-development-kits-for-4d-millimetre-wave-imaging

Mini Circuits has expanded its collaboration with 4D radar imaging pioneer, Vayyar, to offer researchers in the Radio Frequency / microwave industry and academia a ready-to-use, 4D millimeter wave (mmWave) imaging and sensing application development platform.

The VTRIG-74 is a mmWave imaging and sensing development kit powered by Vayyar’s high resolution integrated RF transceiver technology and radar IP.

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Key features of the kit include:

...