Characterization and Design of Wideband Penta- and Hepta-Resonance SIW Elliptical Cavity-Backed Slot Antennas

Substrate integrated waveguide (SIW) elliptical cavity-backed slot antennas (CBSAs) with either penta- or hepta-resonance are characterized and designed for wideband performance in this paper. First, the resonant behavior of the elliptical cavity is explored. Then the SIW CBSA with penta-resonance is designed by introducing a cross-shaped slot and a pair of unbalanced shorting vias into the cavity to excite two additional odd- and even- half degenerate quasi-TM
₁₁₀
modes, besides other three modes of half quasi-TM
₀₁₀
, and odd- and even- quasi-TM
₁₁₀
. Further, by adding another pair of unbalanced shorting vias, two extra higher-order modes, i.e., odd- and even- quasi-TM
₂₁₀
modes are successfully introduced to design a hepta-resonance antenna. The corresponding mode analysis and design guidelines are discussed in detail. Two prototypes are fabricated and measured at X-band, exhibiting the measured bandwidths of 21.8% and 22.7%, respectively. Measured results agree well with simulations, thus validating the design concept.