Electronics > RF, Microwave, Ham Radio
Can a SigGen+SA+Directional Coupler be used as a Poor Man's Scalar Analyzer?
niconiconi:
For some simple experiments, I'd like to test the level of impedance mismatch caused by component footprints on PCB microstrip layouts, up to 3 GHz. I don't have a VNA for that, but I do have a spectrum analyzer and signal generator. I believe all I need is scalar data, namely S11 magnitude in decibel, and low frequency data below 1 GHz doesn't matter, is it possible to make a poor man's Scalar Network Analyzer with an inexpensive directional coupler?
radiolistener:
No
hendorog:
Yes you can make an SNA that way, but you would need some sort of cunning plan to have some confidence that you were measuring the footprint instead of everything leading up to it.
joeqsmith:
--- Quote from: niconiconi on July 12, 2021, 07:16:28 am ---For some simple experiments, I'd like to test the level of impedance mismatch caused by component footprints on PCB microstrip layouts, up to 3 GHz. I don't have a VNA for that, but I do have a spectrum analyzer and signal generator. I believe all I need is scalar data, namely S11 magnitude in decibel, and low frequency data below 1 GHz doesn't matter, is it possible to make a poor man's Scalar Network Analyzer with an inexpensive directional coupler?
--- End quote ---
Yes, a scalar network analyzer can be made with a tracking generator and spectrum analyzer. There is no need for a coupler. Impedance is a complex number and you're missing half the data. Maybe I am not understanding what you are asking or how you plan to get the complex data.
radiolistener:
--- Quote from: joeqsmith on July 12, 2021, 11:45:55 am ---Yes, a scalar network analyzer can be made with a tracking generator and spectrum analyzer.
--- End quote ---
How? I think this is impossible, because there is needs at least measurement bridge.
I tried to use tracking generator with logarithmic power meter and measurement bridge to measure SWR. It can be used for SWR estimation. But it works terrible and needs a lot of movement to calibrate such installation. It's much easier to buy NanoVNA because it will give much better results and more easy to use.
And I would like to see how such DIY installation will be used to inspect a small impedance variations along the microstrip line on a PCB. :)
Navigation
[0] Message Index
[#] Next page
Go to full version