Estimation of delay time difference through space for phased array antennas with true time delay

Abstract

Large aperture and wideband phased array antennas use both phase shifters for each element and true time delay for each subarray to avoid squint. Thus both phase shifter calibration and true time delay calibration are required. In this paper, we focus on true time delay calibration, and propose a method that conducts measurements through space to estimate the delay difference between two subarrays. Our method is essential in systems for which wired measurements are impossible. Additionally, phase measurement is not required in our method because the delay difference is estimated from just the level variation. Experiments and their results are detailed. Delay difference could be estimated with error of 0.37λ or better.