On Alternative Approaches to Design of Corporate Feeds for Low-Sidelobe Microstrip Linear Arrays

Abstract

Two design approaches, illustrated by simulations and measurements, aiming at a systematic computer-aided design of printed circuit feeds for low-sidelobe microstrip antenna arrays are described. The novelty of these approaches resides in identification of the optimal feed architectures with subsequent simulation-based optimization of the feed and array aperture dimensions. In this communication, we consider microstrip corporate feeds (CFs) realizing nonuniform amplitude excitation of linear arrays of microstrip patch antennas. Two types of the microstrip CFs are considered: with equal power split junctions and with unequal power split junctions. For each feed type, we identify candidate prototypes of feed architectures using numerical optimization of the corresponding fast feed models. Subsequently, the architectures are implemented as microstrip subcircuits within the antenna array electromagnetic (EM) models. For the sake of comparison, the antenna array circuits are defined with the same linear array of microstrip patch antennas featuring the half-wavelength element spacing, and implemented on the same microstrip substrates. Finally, the EM models are tuned—using simulation-based optimization techniques—to ensure an appropriate input reflection coefficient and minimum sidelobe levels. Selected optimal designs of antenna array circuits with 12 microstrip patches and different feeds are manufactured and measured.