Tuning of Passbands in Compact Substrate Integrated Waveguide Bandpass Filter using perturbation slot

Tuning the center frequencies and bandwidth of dual passbands using circular arc perturbation slot in compact substrate integrated waveguide (SIW) filter is presented here. A miniaturized SIW cavity is extracted from circular SIW cavity and perturbation slot is loaded to disturb the excited modes. After rightly placing the slot, the arc angle is adjusted to change the surface current path of the excited modes and control the frequency of resonance and passband bandwidth. 1stpassband center frequency (CF) can be tuned within a range of 1.23 GHz while 2ndpassband remains almost unchanged when the slot is placed 12 mm away from cavity center. If the slot is placed 8 mm away from the cavity center, 1 GHz shift in CF and 1.2 GHz change in 3dB BW of 2nd passband is attained keeping 1stpassband undisturbed. Minimum insertion losses of passbands during the process of tuning are maintained within 1.2dB.