Build a Phased-Array Radar in Your Garage That Sees Through Walls (2015) | Hacker News Reader

Build a Phased-Array Radar in Your Garage That Sees Through Walls (2015)

hackaday.com

208 pointsdmmalam19 comments

This is cool.

Radar's ability to steer the beam without moving always seems almost magical to me.

Fun fact: Radars control/ signal processing are now software.

Some caution is in order when playing with these things, remember, microwaves aren't just for radar they're for cooking too (one of the original microwave oven was called "radarrange")

https://en.wikipedia.org/wiki/Percy_Spencer

I implemented/updated code that analyzed a radars output and made sure that the side lobes weren't cooking people if they happened to be standing around the radar (or in the control house which was shielded). Even if you aren't in the path of the radar (eg its pointed up) there is some rf being spilled down by side lobes. work radar was significantly larger than this one, but on this one you can stand right in its beam path.

"Fun fact: Radars control/ signal processing are now software."

Well some of it. I'd call base-band processing in FPGA as hardware, as RADAR bandwidths are generally still too high to allow real-time processing in software; i.e a true software defined radar on a CPU. The software is always playing catch-up as bandwidths and array density increase.

Even 2G wireless comms still are not fully software; it take an FPGA implementation due to latency. Never mind 5G comms.

I suppose it's a point of contention, but I don't consider HDL to be software, as it's easier to go from (an HDL synthesized to) FPGA to an ASIC than HDL to software on a general purpose CPU.

I've never met anyone who designs ASICs or FPGAs professionally that thought HDL was software. I'm not sure it is contentious.

Our shop treats our FPGA HDL as software.

What does your company do?

Robotics.

I'm very curious about Fpga applications. Can you share any details? (Company name, target application, verilog vs vhdl, etc.)

That transition to software is what makes this so approachable. Also exciting that cars are starting have radar where volume will bring down price to something accessible to people outside of aerospace.

The most exciting thing for mobile robotics is that soon LIDAR will be solid state (like RADAR is today). See Quanergy.

This will bring the cost and size of precision proximity/ranging/mapping sensors down by an incredible amount.

What happens if you get in the path of a microwave beam at this kind of power? I'd imagine you notice your skin getting hot. What's the biggest risk? (I'm not saying I'm OK having my eyeballs heated, I'm just curious about what the biggest dangers are.)

Eye lenses and testicals are the the things that are effected most quickly if I remember correctly.

https://en.wikipedia.org/wiki/Microwave_burn

The microwave oven was actually invented by a guy who walked in front of a powerful radar with a candy bar in his pocket, and had a eureka moment when it melted.

It seems that they figured out modern microwave cookery very quickly. The first thing they cooked on purpose was popcorn, and the second was an egg, which exploded.

> [...] and made sure that the side lobes weren't cooking people if they happened to be standing around the radar

But what if your neighbors build a reflector dish specifically aimed at cooking any see-through-wall-radar-operators?

Not too many people can build such a thing in their garage...

Has anyone considered "phased array" optics?

Yes. Phased array optics is a thing.

You can build lens from dielectric material with a refractive index > 1, or metal lens from metal plates if you need refractive index < 1.

You can also build a lens from beam-forming network. Rotman lens is part of many AESA radar elements.

Yes. https://en.wikipedia.org/wiki/Phased-array_optics

Needs a 2015 perhaps?

Reply on news.ycombinator.com