Design and Measurement of a Microstrip Antenna Array on a Broad Wall of a Rectangular Waveguide for 45-Degree Linear Polarization

Abstract

This paper presents a microstrip antenna (MSA) array on a broad wall of a rectangular waveguide for 45-degree inclined linear polarization. A two-element MSA array connected by a microstrip line at the corners on a dielectric substrate, which is fed by an inclined slot on the broad wall of the rectangular waveguide, is used as a sub array of the proposed array for grating lobe suppression due to the slot array arranged at a spacing of one guided wavelength. In this paper, a basic configuration of the novel planar array for 45-degree linear polarization on a broad wall of the rectangular waveguide is described. Then, a six-element MSA array fed by three inclined slots on the broad wall with standing-wave excitation is designed by using ANSYS HFSS and a prototype array is fabricated. The measured radiation pattern of the prototype array is agreed well with the simulated one and reveals that the grading lobes due to the inclined slots arranged at a spacing of one guided wavelength can be suppressed below −10dB.