http://github.com/profdc9/VNA

A two port vector heterodyne network analyzer for frequencies 200 kHz to 500 MHz based on the STM32F103C8T6 Bluepill and can be constructed at a very low cost from readily available components. It has touchscreen support using a ILI9341/XPT2046 based touchscreen, or it can be used with the USB serial support only using a terminal program. It can perform reflection or transmission measurements with an impedance range of about 1 to 10000 ohms or about 50 dB of dynamic range, with full phase measurement capability. The VNA supports open/short/load/thru calibration. PCB designs are available for both through-hole and SMT. It has limited MiniVNA compatible support.