Fun facts, you can build your own VNA from scratch using open source GNU Radio toolkit with any off-the-shelf SDR platform for example using the low-cost ADALM-Pluto or you can go fully gung ho with the more capable RFSoC platform [1],[2],[3],[4]:<p>[1] Lab notebook of experiments in GNURadio:<p><a href="http://www.swigerco.com/gnuradio/" rel="nofollow">http://www.swigerco.com/gnuradio/</a><p>[2] Off-the-Shelf Reconfigurable Software Define Radio Approach for Vector Network Analyzer:<p><a href="https://jati.apu.edu.my/files/2018/12/2018_Issue2_Paper1.pdf" rel="nofollow">https://jati.apu.edu.my/files/2018/12/2018_Issue2_Paper1.pdf</a><p>[3] ADALM-PLUTO: Software-Defined Radio Active Learning Module (USD230):<p><a href="https://www.analog.com/en/resources/evaluation-hardware-and-software/evaluation-boards-kits/adalm-pluto.html" rel="nofollow">https://www.analog.com/en/resources/evaluation-hardware-and-...</a><p>[4] RFSoC 4x2 Development Kit Overview (USD2K):<p><a href="https://news.ycombinator.com/item?id=39427825">https://news.ycombinator.com/item?id=39427825</a>