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° with respect to the feeding slot. It produces left-hand CP with a bandwidth of 0.22 GHz (0.36%). A 2 × 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 × 2 SIW-DRA elements with 90° orientation rotation angle and phases of 0, 90°, 180°, and 270° 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.