Design of a Dual-Layer Filter-Antenna with Good Frequency Selectivity

The proposed antenna is based on a dual-layer Substrate Integrated Waveguide (SIW) cavity structure, designed to achieve both radiation and filtering characteristics within a compact form. The SIW cavity is realized by placing periodic metallic vias along the edges of the substrate, which act as sidewalls and confine electromagnetic waves within the structure. The top and bottom metal layers serve as conducting planes, forming a closed waveguide-like configuration. The antenna consists of two stacked dielectric layers. The bottom layer primarily supports the SIW cavity and guides the electromagnetic energy, while the top layer contains the radiating slot responsible for energy radiation into free space. A coupling slot is introduced between the layers to enable controlled energy transfer from the cavity to the radiating element. The geometry of the antenna is carefully designed to ensure proper interaction between the cavity modes and the slot. Key structural parameters include the slot length, slot width, via diameter, and via spacing, all of which influence the resonance behavior and radiation characteristics. The dual-layer arrangement enhances coupling between modes, which is essential for generating radiation nulls and achieving frequency selectivity. Overall, the configuration provides a compact and efficient platform for integrating filtering functionality directly into the antenna structure, eliminating the need for additional filtering components.

The obtained results demonstrate that the proposed antenna successfully achieves: ⚫ Good impedance matching at the operating frequency ⚫ Efficient radiation with moderate gain ⚫ Controlled bandwidth ⚫ Effective suppression of unwanted frequencies through radiation nulls These results confirm that the antenna integrates both radiation and filtering functions within a compact structure, making it suitable for practical wireless communication application