Wideband 4 by 4 Microstrip Antenna Array with H-Slot Coupling for Ka-Band LEO Satellite Communications

Abstract

This paper presents the design, implementation, and measurement of a wideband 4x4 microstrip antenna array for Ka-band (27.5–31 GHz) Low Earth Orbit (LEO) satellite uplink applications. To address the bandwidth limitations of conventional microstrip antennas, a H-shaped slot coupled feeding mechanism is utilized in a stacked substrate configuration. A symmetric X-axis feeding network is designed to enhance phase consistency and minimize radiation loss. The fabricated array demonstrates a measured impedance bandwidth of approximately 30.6%, fully covering the required uplink frequency band, with a peak realized gain of 15.4 dBi. Furthermore, this study experimentally investigates the sensitivity of millimeter-wave antenna performance caused by fabrication tolerances. The effects of the air gap between substrate layers on impedance matching and radiation patterns are analyzed, providing critical insights for practical ground station deployment. Good agreement between simulation and measurement results validates the effectiveness of the proposed design.