Abstract
In this article, a design of planar cavity‐backed antenna‐triplexer is proposed for WLAN/WiMAX/ISM band at 5.2/5.5/5.8 GHz. The substrate integrated waveguide (SIW) technology is employed to realize a planar cavity‐backed antenna‐triplexer. The proposed geometry entails two SIW cavity resonators where a bowtie‐shaped smaller cavity is inserted inside the larger rectangular one. The rectangular cavity consists of two bent‐transverse slots those are excited by two different microstrip feedlines and the Bowtie‐like slot inside the Bowtie cavity, excited by a coaxial feed. The antenna generates three different resonances at 5.2, 5.5, and 5.8 GHz simultaneously with flat gain characteristics. By exciting cavity modes (TE110) by Port2/Port3 and a patch mode (TM010) by Port 1 simultaneously, average isolation of better than 23 dB is accomplished among the three input ports. To validate the proposed idea, the design is fabricated and experimentally tested. The measured responses show a good matching with the simulations. Moreover, the antenna shows front to back ratio better than 18 dB and simulated gain values of 7, 5.45, 4.75 dBi at the three resonances.