A Bandpass Filter With Switchable Frequency and Bandwidth on Substrate Integrated Waveguide

This paper presents a substrate integrated waveguide (SIW) bandpass filter with switchable center frequency and bandwidth (BW). PIN diodes are used to control the on-off between the via posts and the ground or to change the length of the slot line. When the via posts located in the middle of the resonator is grounded, the electric field is disturbed and the frequency rises. When the column at the coupling window is grounded, the coupling quantity decreases and the bandwidth also decreases. Thus the BWs and frequencies can be switched in the same filter. The SIW filter has three center frequencies that can be switched: 2.62 GHz, 2.86 GHz and 3.10 GHz. And there are two switchable BWs for each center frequency. Return loss is better than 13 dB and insertion loss range from 1.58 dB to 2.25 dB.