2010 IEEE MTT-S International Microwave Symposium Technical Program

Session: WE1B	New Synthesis Techniques for Filter and Multiplexers
Chair:	Ming Yu, COM DEV
Co-Chair:	Giuseppe Macchiarella, Politecnico di Milano
Abstract:	This section presents recent achievements on filters and mutiplexer synthesis techniques. In particular new broadband, dualmode and multiband filters as well as multiplexer networks are discussed.

WE1B-1	Design of Triplexer Combiners for Base Stations of Mobile Communications
8:00 AM-8:20 AM	G. Macchiarella¹, S. Tamiazzo², ¹Politecnico di Milano, Milano, Italy, ²Andrew Telecommunication Products, Agrate Brianza, Italy
(1076)	This work presents a design technique for triplexers composed by three high selectivity filters presenting arbitrary transmission zeros (both complex and pure imaginary), which are connected at the input port through a 4-port junction. The design consists in a procedure for the evaluation of the characteristic polynomials of the three composing filters, once the input junction topology and the transmission zeros of the filters have been assigned. The network synthesized from the characteristic polynomials presents the same reflection zeros of the three filters synthesized separated from the triplexer with an equiripple response in their respective passband; in this way the overall synthesized triplexer presents a quasi-equiripple response in the three passbands.The proposed design approach has been verified through a fabricated prototype, whose measured performance is in good agreement with the expected response obtained from the synthesized network.

WE1B-2	Direct Synthesis of General Chebyshev Bandpass Filters with A Frequency Variant Complex Load
8:20 AM-8:40 AM	M. Meng, K. L. Wu, The Chinese University of Hong Kong, Hong Kong, Hong Kong
(1493)	This paper presents a direct approach to the synthesis of a general Chebyshev coupled resonator filter with a frequency variant complex load. The new approach is based on the power wave renormalization of admittance parameters of a matched filter with a complex load to unitary load. When the port reference is changed from a complex load to a real load, a set of new expressions of admittance parameters can be obtained for the same filter. By introducing a piece of dispersive transmission line to the original matched filter, the poles of the original admittance parameters are retained, which greatly facilitates the extraction of the new admittance parameters, and consequently the synthesis of the coupling matrix. The approach is applicable to the synthesis of an optimal channel filter of a diplexer and a multiplexer, where the load presented at a port of the filter is a frequency variant complex load in a wide frequency range.

WE1B-3	New Distributed Model for Synthesis of Classical Dual Mode Filters
8:40 AM-9:00 AM	S. Cogollos¹, M. Brumos¹, V. E. Boria¹, C. Vicente², B. Gimeno³, M. Guglielmi⁴, ¹Universidad Politecnica de Valencia, Valencia, Spain, ²Aurorasat, s.l., Valencia, Spain, ³Universidad de Valencia, Burjasot, Spain, ⁴European Space Research and Technology Centre (ESTEC), Noordwijk, Netherlands
(1148)	Up to now, distributed models for classical dual mode filters have not been developed. In this paper, the whole procedure to derive such distributed models is shown step by step. The resulting formulas are very similar to those standard ones used for in-line filters since the 1960s. Model limitations, very similar to those related to classical formulas, in terms of precision and bandwidth, are pointed out. Finally, two practical examples of distributed models of dual mode filters for satellite transponders with different orders have been extracted.

WE1B-4	Wide-Band Bandpass Filters Simulation, Design and Diagnosis
9:00 AM-9:20 AM	H. Lee¹, K. A. Zaki¹, A. E. Atia², ¹University of Maryland, College Park, United States, ²Orbital Sciences Corporation, Dulles, United States
(1169)	Full wave EM modeling is used to design wide bandpass filters and extract a lumped elements equivalent circuit. Electric and magnetic couplings are represented by capacitor- and inductor-coupling elements instead of frequency-independent reactance or impedance inverters. Optimization is used to extract the filter parameters that reproduce the EM simulated response. To verify the validity of the circuit model, an 8-pole combline-like filter with a 50% bandwidth is designed. Excellent agreement between the EM simulated and the lumped elements extracted responses is obtained. Filter synthesis is also carried out by an optimization process. With the extracted and synthesized parameters, the filters can then be diagnosed and fine tuned efficiently.

WE1B-5	Tri-band Filter Design using Substrate Integrated Waveguide Resonators in LTCC.
9:20 AM-9:40 AM	W. Tsai¹, R. Wu², ¹Graduate Institute of Communication Engineering, Taipei, Taiwan, ²Graduate Institute of Communication Engineering, Taipei, Taiwan
(1349)	This paper exploits the modal orthogonality to present a new design technique for tri-band filters with minimum number of resonators. Taking advantage of the multiple modes inside one substrate integrated cavity, the coupling mechanisms for different pass bands can be selectively controlled by the modal field distributions. Thus, a tri-band filter of four-pole quasi-elliptic response can be realized by four resonators only. Also, the design can facilitate the feeding design to meet the required external quality factor at the three bands simultaneously. In terms of low-loss co-fired ceramic (LTCC) technology, the cavities are vertically stacked, and the filter size can be miniaturized.

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