Measurement of a microstrip antenna array fed by longitudinal slots on a narrow wall of the rectangular waveguide with standing-wave excitation for linear polarization perpendicular to the axis

This paper presents measurement of a microstrip antenna array fed by longitudinal slots on a narrow wall of the rectangular waveguide with standing wave excitation for linear polarization perpendicular to the axis. A dual-ring microstrip antenna with a circumference of 5 wavelengths excited by the longitudinal slot on the narrow wall of the waveguide with a dielectric substrate is used as an element of the proposed array for grating lobe suppression due to the longitudinal slots arrayed at a spacing of one guided wavelength. In this paper, a prototype array consisting of the dual-ring microstrip antennas fed by three longitudinal slots on the narrow wall of the rectangular waveguide with standing-wave excitation is designed and fabricated. The measured results are agreed with the simulated ones obtained by HFSS. The measured radiation pattern reveals that grading lobes due to the longitudinal slots are well reduced by the proposed array. Validity of the design of the proposed array is confirmed by the measurement.