Compact Quarter-Mode Substrate-Integrated Waveguide Dual-Frequency Millimeter-Wave Antenna Array for 5G Applications

A compact linearly polarized quarter-mode substrate-integrated waveguide (QMSIW) dual-frequency millimeter-wave antenna is presented in this letter. The antenna has two unequal-sized quarter-mode parts of two square substrate-integrated waveguide (SIW) cavities for two operating bands. Each quarter can be tuned independently. The two quarters are realized within one layer of substrate laminate and are placed in a back-to-back configuration, sharing the same row of metalized vias, which makes the structure very simple and compact. For the demonstration, a QMSIW dual-frequency antenna simultaneously operating at 28 and 38 GHz bands was designed for fifth-generation (5G) applications. Compared with a traditional full-mode SIW slot antenna, our element design merits in an antenna footprint miniaturization of 53.5%. A four-element corporate-fed antenna array was also designed, fabricated, and measured. Good agreement between the measured and simulated results is obtained. The measured peak antenna gains of 9.5 dBi and 11.0 dBi are obtained for the lower and upper bands, respectively.