Design and Implementation of Novel H-Shaped Self-Diplexing SIW Rectangular Cavity-Backed Antenna with Harmonic Suppression for Terrestrial Communications

A novel and low profile, planar, rectangular cavity-backed self-diplexing substrate integrated waveguide (SIW) antenna with H-shaped slot for dual-band wireless services was designed and demonstrated. The proposed antenna structure radiates from H-shaped slot, which is etched on top of the SIW rectangular cavity, and is excited by two separate 50 Ω microstrip feed lines. The H-shaped slot is a combination of two vertical slots and one horizontal slot; because of that the presented antenna radiates at two distinct frequency bands around 8.95 GHz and 10 GHz, simultaneously. The design methodology results show that the H-shaped slot is significantly more effective than various other slots in the proposed geometry to suppress the unwanted harmonics, attaining good impedance matching and bandwidths and achieving better isolation between these two ports. Hence, the complete design mechanism helped to achieve self-diplexing characteristics. Furthermore, a self-diplexing H-shaped SIW rectangular cavity-backed antenna was fabricated and characterized for the complete demonstration purpose and found good covenants between the simulated one. Measured results show that the presented designed has impedance bandwidths for the lower and upper frequency bands of around 2.0% (8.89–9.03 GHz) and 3.1% (10.01–10.32 GHz), respectively, and obtained maximum measured gain of 5.11 dBi and 5.41 dBi at 8.95 GHz and 10.15 GHz, respectively. The proposed self-diplexing SIW rectangular cavity-backed structure shows that front-to-back ratios (FTBRs) are more than 21 dB, and on the other side, it provides good isolation between the two ports, which is more than 20 dB.