This is really three tools in one: a sine wave generator (0-72MHz @ 0dBm), a power detector (LF-500MHz, -70dBm to +10dBm), and, when used in concert together, a scalar network analyzer.
The license is the MIT License, as it seems to have almost no restrictions on use. Do what you will with it, just don’t hold me liable if it goes wrong.
As an electrical engineer, I love test kit. However, it’s really expensive. I have the idea of building a Spectrum Analyzer with a dual conversion superheterodyne architecture. It would cover DC to daylight and be everything I’d ever wanted…
But I decided to start smaller. Besides, one of the most important parts of a Spec An is the RBW filter. How do I know if I had a good one? I could use the Spec An itself to tell me or I could make a simpler piece of test kit (this Network Analyzer shield) that would help out in building all manner of RF things.
This was a great way to get my feet wet and learn many things about building circuit boards for RF work. What you see here is Rev 2. Rev 1 had many issues, the worst of which was the amplifier on the output. I used an Op Amp which couldn’t swing rail to rail so I was getting lot’s of distortion (that I could see on my Rigol 70MHz scope) and also made a really great oscillator at ~600MHz (which I only found when I put it on a Spec An at work (+3dBm… my bad, FCC, when I hooked it up to a short piece of wire and briefly listened to my sine wave signal on a short wave receiver)). I also screwed up the DC biasing… Oh well, that’s why I made Rev 2!
I wrote a program to display the trace and control the board in Python. It has a known error where sometimes when decreasing the number of samples in a sweep, it throws an index out of array bounds error and stops working. I could fix it by putting a state machine into the program, but it works pretty well as is so I haven’t done that yet.
Read more: Arduino Network Analyzer