Cost-Effective Near-Field Calibration for Uniform Linear Array Antennas

This paper presents a novel near-field calibration method for uniform linear arrays (ULAs) without requiring anechoic chambers. Our approach uses a single near-field source transmitting frequency-modulated continuous-wave (FMCW) signals. We propose a joint gradient descent algorithm that simultaneously estimates array error parameters and precisely locates the calibration source, initialized with an approximate source position. The method leverages FMCW signal characteristics to model channel delay and phase errors. Through simulations, we determine optimal signal-to-noise ratio (SNR) and iteration requirements. The algorithm's effectiveness is validated on a 64-antenna ULA, demonstrating improved performance in ranging and back-projection imaging applications. This cost-effective technique offers a practical solution for ULA calibration in non-ideal environments, potentially expanding the use of high-precision phased array systems.