https://www.allaboutcircuits.com/news/teardown-tuesday-hb100-doppler-radar-module/
Join us as we crack open an HB100 Doppler radar module and delve into the mysteries of RF component design.
In this special edition of Teardown Tuesday, we crack open an HB100 Doppler radar module and delve into the mysteries of RF component design.
The HB100 Doppler Radar module costs about $5 from the usual online suspects, which is down at the "insanely cheap" end of the spectrum when you're talking about 10Ghz radio gear. Does it work? Surprisingly, yes. It needs some support components for most uses (like a post-amplifier for the "couple of millivolts" signal it outputs) but does its part of the job well enough.
[...] Frankly, I was rather shocked by what I found. I wasn't expecting much, but I got far less.
I don't know who designed this, but they were a master of the black art of Radio Frequency waveguide engineering. I am impressed. The PCB, itself, is a major component. Not only for the patch antennas but also several RF filters, the local oscillator, and the mixer are all largely made from peculiarly-shaped PCB tracks.
What would you build with it?
(Score: 4, Interesting) by VLM on Saturday July 06 2024, @04:00PM (1 child)
For more DRO fun you can check out direct broadcast satellite LNBs that are essentially free at rummage sales and thrift stores (for DirectTV and similar). They are not frequency stable enough for narrowband stuff but are "stable enough" for digital TV satellite service or screwing around with ham radio stuff. An interesting, weird, cool, tech.
The article author seemed confused about YIG technology when he was pondering if the DRO used magnets somehow. YIGs are cool but a BIT power hungry. Like watts of input to get a couple dBm of output. They are also cool tech but I don't know how you get one other than being ungodly wealthy or mil surplus. YIGs are the components that made HP 1980s microwave gear have six digit price tags. I bought a stack of them at a hamfest "decade or two ago" for pretty much nothing, thought I was wealthy, but little $20 solid state VCO modules have taken over the industry so they are indeed worth like $1 a piece now. Funny that a replacement YIG used to sell for more than a new car in the 80s, but times change fast in electronics hardware...
(Score: 5, Interesting) by VLM on Saturday July 06 2024, @04:09PM
Correction, $1 a piece for hobbyist use, unknown condition, no serial number, etc.
Famously there's a guy on ebay selling refurb and tested HP YIGs for a cool kilobuck a piece. Not new, but repaired. New in box, back when they were available, were like $20K and up.
If you've ever wondered why you can get "untested" aka broken HP microwave gear from the 80s up to 90s for only $100, but guaranteed tested and working to published spec is like $1100, well, this one single component is why.
Something in the yig wears our or breaks over time; I don't know what, thermal expansion/contraction stress, or physical shock or maybe some slow corrosion, donno? In theory a YIG should run forever, but they sure as hell do not, and are very expensive to repair, something of a miracle they're repairable at all.