Microstrip Grid and Patch-Based Dual-Band Shared-Aperture Differentially-Fed Array Antenna

The design of a shared-aperture dual-band differentially-fed array antenna with microstrip grid and patches is presented in this paper. The patches as high frequency elements operating at 38 GHz are inserted into microstrip grid array antenna (MGAA) operating at low frequency band of 28 GHz. The impedance bandwidth of MGAA can be enhanced from 3% to 16% at 28 GHz, due to the introduced resonance from its coupling with the patches. The measurement shows the proposed antenna can achieve impedance bandwidths of 15.65% and 16.7%, isolation of more than 20 dB, and peak gains of 14.7 dBi and 14.5 dBi at dual-band of 28 GHz and 38 GHz, respectively. Therefore, the design scheme will be useful for dual-band millimeter-wave 5G applications.