Triple-Mode Cavity Bandpass Filter on Doublet With Controllable Transmission Zeros

On the basis of doublet and its properties, a class of multiple-mode narrow band bandpasss filter is designed and fabricated by simultaneously exploiting the three resonant modes in a single rectangular cavity: TE101, TE011, and TM110 modes. The input/output ports of the proposed filter are fed by coupling a microstrip line to a slot on the side wall of a rectangular cavity. Different modes are excited by changing the position and shape of the two slots at input and output of the rectangular cavity without any intra-cavity coupling. Besides three poles within the passband, a pair of transmission zeros (TZs) is achieved, which can be controlled independently by setting the positions of the two TZs at the lower and/or upper stopband. High stopband attenuation and high filtering selectivity are achieved by considerably allocating three transmission poles and two zeros. In order to verify the proposed theory, two filter prototypes are fabricated and measured.

[1]  A. Atia,et al.  Narrow-Bandpass Waveguide Filters , 1972 .

[2]  R. Cameron.  Advanced coupling matrix synthesis techniques for microwave filters , 2003 .

[3]  Ming Hui Chen,et al.  Short-Circuit Tuning Method for Singly Terminated Filters , 1977 .

[4]  U. Rosenberg,et al.  Novel coupling schemes for microwave resonator filters , 2002, IMS 2002.

[5]  M. Guglielmi,et al.  Triple mode filters with coaxial excitation , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[6]  A. E. Williams.  A Four-Cavity Elliptic Waveguide Filter , 1970 .

[7]  U. Rosenberg,et al.  Pseudo-elliptic microstrip line filters with zero-shifting properties , 2004, IEEE Microwave and Wireless Components Letters.

[8]  U. Rosenberg,et al.  New in-line dual- and triple-mode cavity filters with nonresonating nodes , 2005, IEEE Transactions on Microwave Theory and Techniques.

[9]  K. Konno,et al.  A compact elliptic-function BPF using triple-mode cavities for terrestrial digital television transmitters , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[10]  M. Guglielmi,et al.  CAD of triple-mode cavities in rectangular waveguide , 1998 .

[11]  G.-M. Wang,et al.  Highly selective bandpass filter based on substrate integrated waveguide , 2009 .

[12]  S. Bastioli,et al.  Nonresonating Mode Waveguide Filters , 2011, IEEE Microwave Magazine.

[13]  Xiao-Peng Liang,et al.  Dual mode coupling by square corner cut in resonators and filters , 1992 .

[14]  Uwe Rosenberg,et al.  The Doublet: A New Building Block for Modular Design of Elliptic Filters , 2002, 2002 32nd European Microwave Conference.

[15]  W. Yin,et al.  A Novel Single-Cavity Dual Mode Substrate Integrated Waveguide Filter With Non-Resonating Node , 2009, IEEE Microwave and Wireless Components Letters.

[16]  Uwe Rosenberg,et al.  New `Planar' waveguide cavity elliptic function filters , 1995, 1995 25th European Microwave Conference.

[17]  S. Amari,et al.  New dual-mode dielectric resonator filters , 2005, IEEE Microwave and Wireless Components Letters.

[18]  Chi Wang,et al.  A practical triple-mode monoblock bandpass filter for base station applications , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[19]  S. Amari,et al.  A universal building block for advanced modular design of microwave filters , 2003, IEEE Microwave and Wireless Components Letters.