Design of A Reconfigurable Filtering Switch with Sharp Rejection and Wide Stopband

This paper presents a reconfigurable filtering switch based on stub-loaded resonators (SLRs). The resonance conditions of SLRs are obtained using the odd-/even-mode analysis. The mechanism of the switching and reconfiguration is then described. By introducing two signals at symmetrical positions of the SLR, the excited odd mode resonance will be canceled out. Controlling the access of the terminal grounding resistors at the stub enables the detuning of the even mode resonance without affecting the odd mode circuits. In the off-state, both resonant modes are detuned, resulting in an ultra-wide stopband with exceptional isolation. A four-pole prototype is designed for validation. The prototype showcases two switchable passbands centered at 1.52 and 2.66 GHz, with the fractional bandwidth of 11.8% and 13.1% and the minimal in-band insertion losses of 1.75 and 2.28 dB, respectively. The off-state isolations are 42 dB and 20 dB for the two operating bands.