Narrow bandpass filters using dual-behavior resonators based on stepped-impedance stubs and different-length stubs

Dual-behavior resonators (DBRs) are based on the parallel association of two different bandstop structures, which implies a constructive recombination. Two kinds of stubs, stepped-impedance and different-length stubs, are examined in this paper. The first section concerns stepped-impedance stubs. We have previously reported some simplifications of the fundamental equations. Here, we propose a new simplification together with synthesis; both allow an independent control of the two attenuated bands. In a second section, a DBR composed of two uniform stubs of different lengths is studied instead of two stepped-impedance open-circuited stubs. This implies a greatly simplified synthesis and implementation. Some other structures combining short- and open-circuited stubs are also introduced. Throughout the paper, simulations are proposed to illustrate the possibilities offered by such topologies. Experimental results in microstrip technology are also presented in order to validate our idea. Finally, benefits and drawbacks of the different structures are discussed.

[1]  C. Quendo,et al.  Integration of optimized low-pass filters in band-pass filters for out-of-band improvement , 2001, 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157).

[2]  A.A. Melcon,et al.  A new simple microstrip open-loop resonators filter for high selectivity applications , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[3]  Eric Rius,et al.  Narrow bandpass filters using dual-behavior resonators , 2003 .

[4]  K. Sarabandi,et al.  Miniaturized slot-line and folded-slot band-pass filters , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[5]  Jr. R. Wyndrum.  Microwave filters, impedance-matching networks, and coupling structures , 1965 .

[6]  Giuseppe Macchiarella,et al.  Single-Sided Filters in Microstrip Technology , 2001, 2001 31st European Microwave Conference.

[7]  Eric Rius,et al.  High Rejection C-Band Planar Band-Pass Filter For a Spatial Application , 2003, 2003 33rd European Microwave Conference, 2003.

[8]  S. Amari,et al.  New parallel /spl lambda//2-microstrip line filters with transmission zeros at finite frequencies , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[9]  C. Person,et al.  Accessing to UMTS filtering specifications using new microstrip miniaturized loop-filters , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[10]  Kouji Wada,et al.  Fundamentals of Open-Ended Resonators and Their Application to Microwave Filters , 2000 .

[11]  Ian Hunter,et al.  Theory and Design of Microwave Filters , 2001 .

[12]  Jen-Tsai Kuo,et al.  A microstrip elliptic function filter with compact miniaturized hairpin resonators , 2000, IEEE Microwave and Guided Wave Letters.