Use S21 mode with an amplifier.
People have been using VNAs as radars for years.
The NanoVNA just makes it easier.
Dealing with the big first reflection is tricky. One way is to use a separate cancellation path that is adjusted to null the first reflection. ?That’s what we did for the FINDER victim detection radar.
FINDER: Radar for Locating Disaster Victims ( )
jpl.nasa.gov ( )
( )
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On Feb 17, 2025, at 08:51, KENT BRITAIN <WA5VJB@...> wrote:
? Hi Larry
I have worked on several GPR projects.? One is currently looking for land
mines in SE Asia.
A LOT of loss going though dirt.??? And a big impedance bump at the
air/dirt interface.
They really need much more power than the Nano puts out.?? And since the
same port is Tx and Rec, an amp will not be simple.????? But lots of neat
stuff down there.?? Kent
On Monday, February 17, 2025 at 10:17:28 AM CST, Larry Rothman via
groups.io <nlroth@...> wrote:
Folks,
Using the NanoVNA as a signal source for Ground Penetrating Radar (GPR)
was discussed a couple of years ago. Today on Hacker News, there is an
article about a home-built Synthetic Aperture Radar (SAR) unit using a
freq around 6GHz.
The article discusses theory and the problem of finding a suitable Rcv
A/D. The LiteVNA has the freq range, is capable of resolving nS time (to a
certain amount), can measure phase and is programmable.
The big issue is probably the switching time of the generator/reflection
ICs in the front-end of the LiteVNA. As for the A/D spec, would the
heterodyne method and DSP used be a limiting factor?
So - might it be feasible to make use of the LiteVNA in a simplified radar
setup using an external controller and appropriate antennas?
Could the TDR routines be adapted?
Could the LiteVNA be used with a TinSA-Ultra and a controller for
something?
Just thinking out of the box here. In my 60+ years of Tech, I have always
looked at repurposing stuff. So, instead of "not possible" answers, I
would rather hear what might need to be changed (electronics /software) to
achieve a minimal proof of concept. Thinking caps on....
... Larry
