28-GHz patch antenna arrays with PCB and LTCC substrates

Ka-band spectrum is relatively abundant and therefore attractive for services of satellite communication, targeting radar, and wireless broadband access technologies. However, Ka-band patch antenna is difficult in realization because the accurate manufacturing is indeed a challenge in obtaining excellent antenna performance at such high frequencies. This study develops three patch antenna arrays for operation at 28 GHz. Two of the three patch arrays with 2×2 and 4×1 patches, respectively, are realized on microwave printed circuit boards (PCBs). The experimental PCB patch arrays have bandwidths up to 5.7% and gains up to 13 dBi. Another 2×2 stacked-patch antenna array is fabricated with low temperature co-fired ceramic (LTCC) technology for further bandwidth enhancement. This LTCC stacked-patch array comprises a novel opposite-side feeding structure to prevent any electrical effect on the parasitic patch. A measured gain of 10.35 dBi and a wide bandwidth of 10.1% (26.75–29.6 GHz) are achieved.