A novel wideband half-mode SIW bandpass filter based on evanescent-mode technique using complementary Z-shaped resonator
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In this paper, a novel wideband bandpass filter using half-mode substrate integrated waveguide (HMSIW) structure loaded by complementary Z-shaped resonator (CZR) is proposed. The working principle of the proposed filter is based on the evanescent-mode propagation. The CZR unit-cell behave as a magnetic dipole, which is able to generate a backward-wave passband region below the cut-off frequency of the SIW–CZR structure. Since, the electrical size of the proposed CZR unit-cell is larger than the conventional complementary electric-LC unit-cell with the same size, therefore this unit-cell is a good candidate to miniaturize the SIW structure. As well as, the SIW filter loaded by the proposed CZR unit-cell presents a wider bandpass compared to the SIW filter loaded by the conventional resonant metamaterial unit-cells. In order to validate the ability of the proposed CZR unit-cell in size reduction and increasing bandwidth, the proposed one- and two-stage HMSIW–CZR filters have been fabricated and tested. The measured S-parameters of the fabricated filters are in a good agreement with the simulated ones. It is the first time that the CZR unit-cells were combined with the SIW structure to miniaturize the SIW structure and increase the bandwidth. The total size of the proposed two-stage filter is 0.62 λg × 0.26 λg.
KeywordsComplementary Z-shaped resonators (CZR) Magnetic dipoles Half-mode substrate integrated waveguide (HMSIW) Evanescent-mode technique Wideband bandpass filter Compact size
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