A CSRR Loaded SIW Based Band Pass Filter with Improved Stop-Band Rejection

This reports the development a complementary split-ring resonator (CSRR) loaded substrate integrated waveguide (SIW) based band pass filter (BPF) with improved stop-band rejection. A step-by-step investigation has been carried out to arrive at the final optimized layout. The filter exhibits centre frequency at 10 GHz and insertion loss lower than 1.5 dB over the pass-band. The operating band is 9.65 GHz to 10.35 GHz (3dB-bandwidth 700 MHz, fractional bandwidth 7%). A very high stopband rejection of 49 dB at the lower stopband and 35 dB at the higher stopband have been achieved. Some slight modifications in the CSRR configuration inhibits the TE<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</inf> mode and produces an improved stopband rejection of 49 dB. The structure shows good filtering response with a substantial roll-off and compact size with a considerable return loss.