A Compact Substrate Integrated Self-Diplexing Antenna for WiFi and ISM Band Applications

In this article a simple compact (0.28 λ
_g
²
) substrate integrated waveguide (SIW) based self-diplexing antenna is proposed. The self-diplexing antenna consists of an SIW cavity, two off-centered stepped patches and two feeding ports. The whole design is developed in a simple three step process. In first step two patches of different lengths are created on the top side and fed separately by two 50Ω feedlines to operate at two different frequencies. In second step, to maintain acceptable isolation the ports are equally off-centered in opposite directions. In the last step, to further improve the isolation the patches are modified to stepped shape. The proposed antenna operates at 5.23 GHz (for WiFi) and at 5.8 GHz (for ISM band) independently/simultaneously with peak gain of 5.22 dBi and 5.1 dBi respectively. At both the resonant frequencies the antenna possesses > 18 dB front-to-back-ratio. Importantly, the design allows each resonant frequencies to be tuned separately using single design parameter. A prototype of the prosed self-diplexing antenna is fabricated and characterized. Good agreement is obtained between the simulated and measured results. As per its performance and compactness the proposed antenna is a suitable candidate for indoor WiFi and ISM band applications.