Probe-based, quasi-near-field phased array calibration

Abstract

Phased array technology provides remarkable scanning flexibility and spatial search capability for the multifunction radar system, airborne radar system, and many other applications. Recent years have seen a noticeable surge towards low cost, small phased array antenna technology in a varied range of sectors due to its diverse applicability. However, lowering the cost exposed phased array antenna to various errors, among which excitation errors, such as incorrect phase and amplitude, is one of the major concerns. Excitation errors affect essential performance parameters such as side-lobe level, antenna gain, active impedance, and beam-forming quality. It is crucial to quantify and compensate for the errors associated with each antenna element's phase and amplitude to ensure the phased array antenna's desired performance. The process of this compensation is widely known as the calibration of a phased array. The diverse application and increased use of a low cost small phased array system make the front end calibration procedure very challenging. This challenge is two-fold. The calibration should be done accurately and quickly as possible. This dissertation focuses on developing a novel technique of phased array calibration using a fixed probe in the quasi-near-field of the antenna. The objective is to significantly reduce calibration time and associated cost without compromising the calibration quality for initial and in-situ calibration. After the development of a successful mathematical framework, a detailed simulation is conducted to analyze the system. The proposed technique was finally validated using an active electronically scanned array inside a custom-made compact range and near field range.