A Low-Cost Vector Network Analyzer based on Software-Defined Radio

The measurement of the scattering parameter $S_{11}$ is fundamental for the characterization of radio-frequency (RF) devices and antennas. This paper presents the development and experimental validation of a low-cost Vector Network Analyzer (VNA) based on Software-Defined Radio (SDR), using the BladeRF platform. The system operates in full-duplex mode, enabling simultaneous transmission and reception across a frequency sweep. An Open-Short-Load (OSL) calibration method was implemented using the scikit-rf library in Python. Results obtained with physical calibration standards and a Vivaldi antenna show high agreement with a commercial VNA (HP 8722D), achieving magnitude errors below 0.13 dB and phase deviation within 12.3°. These findings validate the system’s metrological accuracy and robustness under non-ideal conditions. The proposed SD-VNA offers a flexible and accessible platform for RF education, antenna prototyping, and emerging biomedical imaging applications.