55-GHz Low Sidelobe Ring-Loading Patch Antenna on LTCC Technology

A 2×2 ring-loading rectangular patch antenna array with high gain and low sidelobe is proposed and designed at 55-GHz. The antenna array consists of a H-type substrate integrated waveguide (SIW) power divider, rectangular substrate integrated cavity (SIC), and radiation elements. The radiation element comprises a ring-loading rectangular patch and a backed cavity. A wide coupling slot on the upper surface of the SIC is used to excite the patch while the longitudinal slot on the SIW couples electromagnetic waves into the SIC. The proposed antenna array achieves a low sidelobe level below 13 dB by reducing the spacing of antenna elements. Simulated-results show that 10-dB impedance bandwidth of the proposed antenna array is -19.36% (48.75-59.2 GHz) with a peak gain of 14 dBi at 59 GHz.