Wideband Excitations of Higher-Order Mode Substrate Integrated Waveguides and Their Applications to Antenna Array Design

The utilization of substrate integrated wave-guide (SIW) higher-order modes can significantly reduce the number of metal posts and thus simplify the component structure. In this paper, two wideband excitation structures for higher-order modes in SIWs are proposed and investigated to implement slot arrays. Two parallel coupling slots along the SIW are used to excite the TE
₄₀
mode. The excitation structures exhibit broad bandwidth and good mode purity. Moreover, they can be extended to realize transitions exciting TE
₆₀
, TE
₈₀
,
$\ldots $
, TE
$_{m\mathrm {0}}[m = 6, 8,\ldots 2 \times (n + 3$
), n is a natural number] modes. As application examples, a
$4 \times 4$
-element slot array is designed. Measured results demonstrate that the slot array inherits the merits of the excitation and shows a simple structure, broadside radiation, high aperture efficiency, and good radiation efficiency.