A Technique for In Situ Calibration of an Antenna Array Using Spherical Mode Expansions

In-situ calibration calls for calibrating an antenna array using the signals the array receives while installed in its operational environment. In-situ calibration is advantageous because it can include effects that are traditionally difficult to measure, such as scattering from the array's mounting platform. Many of the current in-situ techniques estimate the Mutual Coupling Matrix (MCM), which is not an appropriate model for many arrays and does not account for platform scattering. To overcome these limitations, we develop an in-situ calibration technique that represents the array response as a Spherical Mode Expansion (SME). Our proposed technique utilizes an alternating minimization algorithm to iteratively solve for both the unknown signals received by the array and the coefficients of the SME. We demonstrate the effectiveness of this technique using a simulation of a moving antenna array affected by platform scattering that receives signals from multiple stationary transmitters.