A Compact Switchable Filtering Diplexer Based on Reused L-Shaped Resonator

A switchable filtering diplexer utilizing a reused resonator is proposed to reduce the size and insertion loss. This diplexer consists of two multi-coupled filters which reuse a switchable L-shaped resonator. The co-design of the input matching network and the shared resonator simplifies diplexer's architecture and reduces the insertion loss further. The fabricated diplexer demonstrates insertion loss of 1.3 dB@ 2.35 GHz and 1.34 dB@ 3.5 GHz, fractional bandwidth of 25%@ 2.35 GHz and 28%@ 3.5 GHz, respectively. The occupied area is as small as 12 × 20 mm2. Compared with reported state-of-the-arts, the fabricated diplexer achieves a lower insertion loss and a smaller size simultaneously.