A New Class of Waveguide Dual-Mode Filters Using TM and Nonresonating Modes

An innovative class of very compact and selective waveguide dual-mode filters is presented in this paper. The basic structure is the TM dual-mode cavity. Such a cavity employs both resonant and nonresonating modes so as to provide two reflection and two transmission zeros. The high design flexibility in terms of transmission zero positioning and response bandwidth has been demonstrated by means of several single cavity designs. The design of Nth-order multiple cavity filters with N transmission zeros is presented and discussed. Different filter topologies are obtained depending on the waveguide structure used to connect adjacent cavities. An efficient mode-matching analysis method is proposed and verified for fast filter optimization. An eighth-order filter with eight transmission zeros has been designed, manufactured, and tested to demonstrate the potentialities of the filter class proposed.

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

[2]  Wai-Cheung Tang,et al.  A True Elliptic-Function Filter Using Triple-Mode Degenerate Cavities , 1984 .

[3]  R. R. Bonetti,et al.  Application of Dual TM Modesto Triple- and Quadruple-Mode Filters , 1987 .

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

[5]  M. Guglielmi,et al.  Accurate CAD for dual mode filters in circular waveguide including tuning elements , 1997, 1997 IEEE MTT-S International Microwave Symposium Digest.

[6]  M. Guglielmi,et al.  A new family of all-inductive dual-mode filters , 2001 .

[7]  P. Guillon,et al.  Microwave filters-applications and technology , 2002 .

[8]  S. Amari,et al.  Adaptive synthesis and design of resonator filters with source/load-multiresonator coupling , 2002 .

[9]  S. Amari,et al.  -Mode Filters With High-Design Flexibility by Utilizing Bypass Couplings of Nonresonating Modes , 2003 .

[10]  Jens Bornemann,et al.  Inline TM/sub 110/-mode filters with high-design flexibility by utilizing bypass couplings of nonresonating TE/sub 10/01/ modes , 2003 .

[11]  U. Rosenberg,et al.  New building blocks for modular design of elliptic and self-equalized filters , 2004, IEEE Transactions on Microwave Theory and Techniques.

[12]  J. Bornemann,et al.  Singlets, cascaded singlets, and the nonresonating node model for advanced modular design of elliptic filters , 2004, IEEE Microwave and Wireless Components Letters.

[13]  U. Rosenberg,et al.  Characteristics of cross (bypass) coupling through higher/lower order modes and their applications in elliptic filter design , 2005, IEEE Transactions on Microwave Theory and Techniques.

[14]  Simone Bastioli,et al.  Ultra-compact highly-selective dual-mode pseudoelliptic filters , 2010 .

[15]  Roberto Sorrentino,et al.  TM dual-mode pseudoelliptic filters using nonresonating modes , 2010, 2010 IEEE MTT-S International Microwave Symposium.