Design of a Wideband Low-Profile Substrate-Integrated Waveguide Antenna with a Gamma-Shaped Slot for mmWave Applications

This paper presents a wideband substrate-integrated waveguide (SIW) cavity based slot antenna. Initially, a fullmode SIW cavity is excited in the T E110 mode employing a tapered feed. Further, an I-shaped conventional slot is etched in the ground plane to radiate energy from the T E110 mode. To convert the narrowband behavior of this slot antenna into wideband, the slot shape is modified to a gamma shape (Γ). As a result, two hybrid, controllable slot modes are excited within the cavity and are coupled to generate wideband characteristics. This novel approach provides the benefits of miniaturization and wideband performance with stable radiation characteristics to the proposed antenna design. A parametric analysis is carried out to optimize the antenna dimensions, and an equivalent circuit model is developed to validate the design. The developed antenna prototype achieves a compact footprint of (0.95λg× 0.95λg× 0.25λg) and offers a 10-dB bandwidth of 3000 MHz (from 22.3 to 25.3 GHz). It provides a gain of more than 4.3 dBi and 58% efficiency across the band. With features like low profile, compactness, wide bandwidth, and decent radiation performance, the antenna is a good fit for handheld mmWave systems.