Novel High-Performance SIW Cavity-Based Switching Structures

In this article, novel architectures for high-speed substrate integrated waveguide (SIW) filtering switches with high-power handling are presented. A four-port filtering double-pole, double-throw (DPDT) switch and a three-port filtering routing switch are demonstrated as a proof-of-concept. For both switches, the structure consists of a main switching circular cavity with concentric posts. These posts enable the excitation of multiple resonant modes. The resonant modes are aligned in frequency using loading capacitances. p-i-n-diodes are used to short loading posts. Consequently, the generated fields interfere constructively and destructively at the output ports. Concept-proving structures are designed, implemented, and measured. For the SIW-DPDT switch, a measured insertion loss and isolation of 2.95 and 26 dB are achieved, respectively, at 7.4 GHz. Furthermore, a 2.98 and 30 dB measured insertion loss and isolation are obtained for the SIW-routing switch, respectively, at 7.7 GHz. The measured insertion losses include the losses of the filtering cavities. The proposed structures share the same switching technique. As a result, the power handling measurements are performed only for the routing switch, which is measured to handle 40 dBm of input power. Also, the employed switching technique is demonstrated to exhibit a switching speed of less than 80 ns.