Design and Evaluation of a Q-Band 4-Element DBF Antenna as Part of Direct Digital RF Transmitter Antenna Modules for On-Board SATCOM Systems

This paper presents the design, fabrication, and evaluation of a circularly polarized Q-band 4×1 digital beam-forming (DBF) array antenna for SATCOM applications. Single beam forming and multi beam forming radiation pattern of the fabricated Q-band array antenna was measured to assess its performance. Conventional analog phased antenna array (PAA) method and DBF method were employed for single beam measurements at 40GHz. Simultaneous multi beam forming measurement at 40GHz and 40.5GHz was also conducted. Measured main polarization gain pattern results closely align with the simulated values, validating the antenna's design. Also, good axial ratio (AR) values across the main lobe are obtained, showing a good polarization purity. Moreover, the array antenna is demonstrated for simultaneous multi beam forming at 0° and - 30°, as well as 0° and +30° main beam direction combinations. The measurement results confirmed the potential of the fabricated antenna array for advanced beam steering applications like SATCOM systems.