Multilayer Substrate Integrated Waveguide Bandpass Filter With Square Complementary Split-Ring Resonators

Using the technology of complementary split-ring resonators (SCRRs), a compact substrate integrated waveguide (SIW) filter is developed with multilayer topology in this paper. Compared to the conventional rectangular type, this filter has compact size, a wider bandpass, high out-of-hand rejection and sharp skirt selectivity. By adjusting the sizes, the angles and the position of the SCRRs, the transmission zero can be created and controlled to improve the frequency selectivity and out-of-band rejection. A 4th-mode bandpass SIW filter with the central frequency and bandwidth are kept at 24GHz and about 40%, respectively, minimum passband insertion loss is 32 dB, and in-band return loss is greater than 10 dB is given and the results showed a good out-of rejection performance.