Circularly Polarized SIW DRA Fed by Ridge Gap Waveguide for 60 GHz Communications

A compact planar dielectric resonator antenna (DRA) is designed based on the substrate integrated waveguide (SIW) technology for 60 GHz communications. The proposed antenna is constructed from a multilayered dielectric substrate separated by metallic sheets. A dog-bone shaped DRA is formed by perforating the upper dielectric substrate with air holes surrounding the dog-bone structure. The DRA is surrounded by metallic vies connecting two metal sheets above and below the substrate containing the DRA. The DRA is fed through a slot coupled microstrip transmission line printed below the slot. The ridge-gap waveguide technology (RGW) is used in the feeding layer to suppress the surface wave surrounding the microstrip transmission line and improve the peak gain. The RGW unit-cell structure has stop-band of 46-95 GHz. The SIW DRA introduces impedance bandwidth from 59.4 to 60.4 GHz (1.67% referenced to 60 GHz) with peak gain of 6.78 dBi. The circular polarization (CP) is achieved by the rotation of the dog-bone shaped DRA by 45 degrees with respect to the feeding slot. It produces left-hand CP with a bandwidth of 0.22 GHz (0.36%). A 2 x 1 SIW-DRA elements are designed with sequential rotation and phases for CP bandwidth enhancement. The peak gain increases to 9.1 dBi, and a broadband AR of 4.8 GHz (8%) is achieved. 2 x 2 SIW-DRA elements with 90 degrees orientation rotation angle and phases of 0, 90 degrees, 180 degrees, and 270 degrees are designed. An improvement in the peak gain of 11 dBi is produced with wide AR bandwidth of 10.8 GHz (18% from 54.2 GHz to 65 GHz) for 60 GHz communications.