A Referenceless Antenna Measurement System Based on Software-Defined Radio [Measurements Corner]

This article introduces a low-cost time-domain near-field measurement system based on softwaredefined radio (SDR). The method is based on using a low-cost receiver to retrieve by Fourier techniques the amplitude and phase of the signal radiated by antennas. The uncertainties introduced by the receiver are modeled and compared with empirical data. Moreover, a setup based on a reference antenna is explored as a possible solution to fix the phase reference of the measurement. The limitations and optimization of the setup are analyzed for different geometries. Some postprocessing techniques are demonstrated to be suitable to overcome the inherent errors introduced by the setup. Once the amplitude and phase are recovered, diagnostic techniques or near-field to far-field transformation can be applied. The results demonstrate the potential and good accuracy of the method for fast and lowcost characterization of antennas when the reference is not accessible.