Fabrication of compact substrate integrated waveguide dual band bandpass filter using complementary split-ring resonators for C and X band applications

• The Design and the optimization of substrate integrated waveguide is done by genetic algorithm and then we Loaded Complementary split-ring resonators (CSRR) at the top layer of the SIW to take advantages of both SIW and CSRRs. The simulation of proposed Filter is done by HFSS software in order to perform the optimal parametric study. • Fabrication of band pass filter is done successfully by LPKF protomat E33 machine, and Rohde/Schwarz ZVB 20 Vector Network Analyzer perform the measure. • The filter has a miniatured size: 13mm*15mm only and displays two passbands: the first has a bandwidth of 2 GHz and resonates at 6.8 GHz, while the second has a bandwidth of 5,55 GHz and resonates at 10.3 GHz. Furthermore, developed BPF filter has low insertion loss: S21=1.7dB and 1.9 dB and improved return loss: S11=24dB and 22 dB, respectively. In addition, two transmissions zero with rejection of 16 dB and 19 dB are achieved at 7.4 GHz and 14.8 GHz. • We have added a parametric study to display the effect of etch geometric parameter on the losses, frequency and bandwidth. This article presents a compact dual-band Bandpass Filter(BPF) based substrate integrated waveguide(SIW) used for C and X band applications. Complementary split-ring resonators(CSRR) are loaded into the waveguide surface to obtain more advantages of compactness and good performance. The SIW cavity undergoes initial optimization utilizing the powerful genetic algorithm, renowned for its robustness in solving complex problems, before proceeding to simulation with Ansys HFSS software with loaded CSRRs. The filter displays two passbands: the first has a bandwidth of 2 GHz and resonates at 6.8 GHz, while the second has a bandwidth of 5,55 GHz and resonates at 10.3 GHz. Moreover, with two resonance frequencies, the developed BPF has the benefit of low insertion loss(S21=-1.7dB and -1.9 dB) and improved return loss: (S11=-24dB and -22 dB) respectively. Furthermore, the proposed combination not only allows the implementation of a forward-wave passband propagating below the characteristic cutoff frequency of the waveguide but also exhibits good rejection, demonstrated by the presence of two transmission zeros with rejection of -16 dB and -19 dB, attained at 7.4 GHz and 14.8 GHz respectively. The proposed SIW BPF was designed using a 0.6mm thick FR4 dielectric substrate measuring 13mm × 15mm. The filter is manufactured to validate the concept and the measured results agree well with the simulation. With all these advantages: compact size, high rejection, and good filtering response, the proposed SIW BPF became suitable for microwave applications.