Single-Layer Dual-/Tri-Band SIW Filtenna Based on Multifunctional Cavity-Backed Slots

Single-layer dual-/tri-band substrate integrated waveguide (SIW) filtenna based on multifunctional cavity-backed slots is proposed in this communication. The cavity-backed slots etched on the SIW cavity can be considered as radiators as well as resonators. When a pair of back-to-back open-loop slots embedded with a straight slot is etched on the SIW cavity, three resonant modes generated by slots combine with the TE101 mode of the SIW cavity to form the superior dual-band filtering response. Moreover, four radiation nulls (RNs) located at both sides of two operational passbands are generated, resulting in sharp roll-offs and deep stopband rejection. To further prove this design concept, a tri-band SIW filtenna is designed by utilizing two pairs of back-to-back open-loop slots embedded with a straight slot, six RNs are introduced in the stopbands, realizing the excellent tri-band filtering performance. The operating mechanism of the proposed antennas is numerically analyzed. Two prototype antennas are fabricated and tested for validation, the center frequencies of the dual-band filtenna are 4.56 and 5.7 GHz, and the tri-band filtenna are centered at 4.1, 4.82, and 5.62 GHz, showing good radiation characteristics in each passband. Compared with other designs, the proposed antennas exhibit the advantages of single-layer structure, small size, and high selectivity, satisfying the requirements of 5G multifrequency communication applications.