5G Antenna in Module (AiM) Architecture to Realize a Large Active Antenna Array with Unequal Shortest Microstrip Paths to Minimize Feeding Loss by Using True-delay Line-based Phase Shifters at Millimeter-Wave Frequencies

Design of Antenna-in-Module (AiM) is presented to realize active and reconfigurable antenna arrays for potential 5G applications at millimeter-wave (mmW) frequencies. Due to the large array configuration, transmission line loss in the dielectric substrates is significant to cause gain degradation and heat issues. To overcome such drawbacks, unequal feeding lines in the beamforming circuits were employed, which were designed based on the available shortest paths. Active digital phase shifters (DPSs) are used to perform the beam steering while, in the meantime, compensate for the phase discrepancy arising from the unequal lengths of feeding lines. For broadband operation, the DPSs are realized by true-delay lines. A calibration technique was employed to perform the phase adjustment. Full-wave simulations by HFSS and experimental measurements on an AiM prototype are presented to validate the feasibility and demonstrate the radiation characteristics.