Modeling and Analysis of Distortions in Amplitude-Tapered Active Phased Arrays Induced by Temperature and Mutual Coupling

Abstract

An iterative electro-thermal modeling framework for active transmitters is presented. The proposed approach comprehensively accounts for antenna impedance matching, mutual coupling among array elements, and the self-heating effects of power amplifiers (PAs). The four-stage iterative procedure begins with the computation of the PA output signal from the input excitation and reflection coefficients, followed by the evaluation of dissipated power, estimation of junction temperature, and subsequent update of the PA signal model. The effectiveness of the method is demonstrated for a 16-element linear array of rectangular patch antennas employing Class-A amplifiers operating at 2.14 GHz. The coupled electromagnetic and thermal behaviors are analyzed under various inter-element spacings, scan angles, and amplitude tapering profiles. Results indicate up to a 3.82 dB reduction in radiated power and a 13 dB increase in peak side-lobe level (SLL) for a 40 dB Taylor taper, underscoring the importance of the proposed joint electro-thermal modeling approach.