Compact Dual-band Bandpass Filter Using Coupled Lines Multimode Resonator

A quad-mode resonator is proposed for novel design of dual-band bandpass filters (DBBPFs) with good selectivity and compact size. The symmetrical resonator consists of a pair of coupled line sections (CLSs) and a transmission line section (TLS). Odd-/even-mode method is used to clarify the mode characteristics. Four excited resonant modes are applied to produce two passbands. The frequency ratio range can be adjusted by the CLSs, and the bandwidths can be controlled by the TLS. After installing a pair of U-shape coupling arms, a DBBPF with five transmission zeros ( TZs) around the two passbands are designed and fabricated. The measured results are in good agreement with the simulated results, demonstrating that the proposed filter is feasible in practical use.

[1]  Lei Zhu,et al.  A Dual-Band Ring-Resonator Bandpass Filter Based on Two Pairs of Degenerate Modes , 2010, IEEE Transactions on Microwave Theory and Techniques.

[2]  V. Krozer,et al.  Coupled Transmission Lines as Impedance Transformer , 2007, IEEE Transactions on Microwave Theory and Techniques.

[3]  Chang-Hong Liang,et al.  Compact Microstrip Dual-Band Bandpass Filter Using a Novel Stub-Loaded Quad-Mode Resonator , 2013, IEEE Microwave and Wireless Components Letters.

[4]  Lei Zhu,et al.  Synthesis Design of Dual-Band Bandpass Filters With $\lambda/4$ Stepped-Impedance Resonators , 2013, IEEE Transactions on Microwave Theory and Techniques.

[5]  Quan Xue,et al.  Dual-Mode Dual-Band Bandpass Filter Based on a Stub-Loaded Patch Resonator , 2011, IEEE Microwave and Wireless Components Letters.

[6]  Xiu Yin Zhang,et al.  Dual-Band Bandpass Filters Using Stub-Loaded Resonators , 2007, IEEE Microwave and Wireless Components Letters.

[7]  Lei Zhu,et al.  Wideband Microstrip Ring Resonator Bandpass Filters Under Multiple Resonances , 2007, IEEE Transactions on Microwave Theory and Techniques.

[8]  Shen Li,et al.  Compact Dual-Band Bandpass Filter Using Quadruple-Mode Square Ring Loaded Resonator (SRLR) , 2013, IEEE Microwave and Wireless Components Letters.

[9]  Lijun Zhang,et al.  A dual-mode dual-band bandpass filter using a tri-stubs loaded multimode resonator (TSLMR) , 2014 .