In this paper, a dual-mode switchable bandpass filter based on open loop resonators and PIN diode switches is designed and implemented. The proposed filter has two center frequency states, one at 1.9 GHz and second one at 2.45 GHz with both providing 9% fractional bandwidth. This filer consists of two open loop resonators which are switched by means of two PIN diodes according to their different bias conditions. In addition, the open loop resonators are chosen to be slow-wave open-loop resonators (OLR) in order to extend their stopband by making their first spurious resonant frequency far away from their center frequency. The bandpass filter is numerically studied based on full wave analysis and one prototype is made and tested. Experimental results show insertion loss of -2.99 dB and -3.14 dB at 2.45 GHz and 1.9 GH, respectively and agree well with those obtained by simulation.

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