COMPACT HMSIW BROADBAND FILTER WITH SYMMETRICAL CSRRS AND METALLIZED HOLES

A simple broadband and wide stopband half-mode substrate integrated waveguide (HMSIW) filter is proposed. Symmetrical complementary split ring resonators (CSRRs) and metallized holes are loaded on the surface of the HMSIW resonator. Metallized holes placed in the center of the CSRRs are used to create two passbands. CSRRs can reduce the return loss of the first passband, and a transmission zero is introduced to suppress the performance of the second passband, thus generating broadband covering the entire X-band. The simulated results show that the center frequency and fractional bandwidth of the filter are 9.26 GHz and 60.7%. There is a transmission zero at 13.18 GHz, and the insertion loss in the range of 12.30 to 21.46 GHz is better than −10 dB, which means that the out-of-band suppression performance is good. The measured results are in good agreement with the simulated ones. This new combination not only obtains broadband frequency, but also makes the filter more compact. The filter has some practical and application significance.