Development of Low-Profile Filtering Antennas With Dual-Mode Cavities

Two filtering antennas implemented on the dual-mode cavities are proposed, investigated and experimentally verified in this paper. They are developed based on the single-layer substrate integrated waveguide (SIW) technology. The rectangular SIW dual-mode cavities (using TE102, TE201 and TE301 modes) are effectively stimulated with a simple capacitive feeding near the diagonal line of the cavity. Surface current distribution is firstly analyzed for the optimal positions of slot radiators. Two rectangular slots are etched on the top surface of the SIW cavity, which are used to interfere the original current flow of one particular mode and generate radiation. These orthogonal dual-modes are used to obtain a filtering response. Their resonance frequencies are close to each other leading to field rotation and interaction with a radiation null generated outside the passband. The radiation and filtering function are achieved simultaneously by the dual-mode cavity, therefore only one cavity is required, resulting in a compact and simple antenna configuration. Good agreement has been observed between the simulation and measurement. They offer a variety of nice features, such as interesting working mechanism, low-profile, high radiation gain and good passband selectivity, which are also suitable for high-frequency antenna application.