Workshops and Short Courses

The design of microwave filters and multiplexers usually starts with the synthesis of an equivalent circuit for determining the optimal architecture of the device. One can observe that the requirements for filtering devices in the last-generation of communication systems have broadened the area of traditional filter synthesis. In the recent years, many studies have concerned the synthesis of advanced filtering devices, such as multiband and broadband filters, compact multiplexers, and more recently synthesis of devices providing both filtering and matching. The objective of this workshop is to provide an overview on recent advances in the field of filter and multiplexer synthesis, and to present new challenges for the next generation of filtering devices. Programme 8:30 08:40 Welcome 8:40 09:10 Coupling matrix synthesis and identification of filters with frequency-dependent couplings and finite resonator Q-factors Michal Mrozowski, Lukasz Szydlowski and Adam Lamecki, Gdansk University of Technology, Poland  Abstract 9:10 9:40 Filter synthesis through polynomial factorization Alejandro Garcia-Lamperez, Universidad Carlos III de Madrid, Spain  Abstract 9:40 10:10 Filter synthesis on a frequency varying load. Application to multi-port synthesis and antenna matching Fabien Seyfert, INRIA, France  Abstract 10:10 10:50 Coffee Break 10:50 11:10 Synthesis of multiport networks consisting of arbitrarily coupled resonators Guiseppe Macchiarella and Stefano Tamiazzo, Politecnico di Milano, Italy  Abstract 11:10 11:35 Synthesis of multi-port Butler matrix with inherent filtering V. Tornielli di Crestvolant and M. Lancaster, University of Birmingham, UK Petronilo Martin Iglesias, ESA ESTEC, Noordwijk, The Netherlands  Abstract 11:35 12:00 Special filter design for SIW-SMW implementation Smain Amari, Royal Military College, Kingston, Canada – Uwe Rosenberg, Mician Global Engineering, Bremen, Germany  Abstract 12:00 12:25 Design of compact multiport filtering devices and subsystems Stéphane Bila, XLIM, Limoges, France  Abstract 12:25 12:30 Discussion WORKSHOPS AND SHORT COURSES 8:40 09:10 Coupling matrix synthesis and identification of filters with frequency-dependent couplings and finite resonator Q-factors Michal Mrozowski, Lukasz Szydlowski and Adam Lamecki, Gdansk University of Technology, Poland Abstract The most common approach to the design of microwave filters with generalized Chebyshev response involves a low-pass prototype of a lossless cross-coupled filter with frequency-invariant couplings. Such a filter is usually represented in the form of a coupling matrix model and the synthesis process finds the elements of the coupling matrix for the assumed filtering network topology. The classical filter theory can be however readily extended to a more realistic case of circuits involving frequency depended couplings and lossy resonators. Such network description offers several advantages such as allowing for design of filters with improved selectivity. What is more, taking into account these effects in the filter synthesis procedure significantly improves the quality of a circuit model resulting in the process of extracting a coupling matrix from measured data. This in turn is instrumental in filter diagnosis and tuning. 9:10 9:40 Filter synthesis through polynomial factorization Alejandro Garcia-Lamperez, Universidad Carlos III de Madrid, Spain Abstract A well-established method of filter synthesis consists of the successive extraction of elements or blocks in a predefined sequence, so that the only unknowns to be computed by the algorithm are the coefficients of those subnetworks. This approach has several drawbacks, namely its limitation to some particular blocks (usually low-order ones) and the numerical instability associated to the accumulated precision loss of each extraction step. Here a generalization of this method, overcoming these problems, is presented. It is based on the factorization of the characteristic polynomials as composition of lower order ones, representing in fact an a priori segmentation of the complete resonator topology as a set of cascaded subnetworks, each one with arbitrary order, transmission zeros and coupling topology. A proposed application for this method is the coupling matrix extraction for optimization, where the topology is only partially imposed. 9:40 10:10 Filter synthesis on a frequency varying load. Application to multi-port synthesis and antenna matching Fabien Seyfert, INRIA, France Abstract Filter synthesis is usually done, by supposing that both input/output ports of the device are matched on a given resistive load (50 Ohm). In this case, an "optimal" filtering response is usually derived from explicit formulas in the case of quasielliptic responses. We consider the problem of synthesizing a filter response, under the hypothesis that the output port is connected to an arbitrary frequency variable load. We prove that, for a filter of MacMillan degree N, and a given transmission polynomial there exists a unique filtering response matching the load in N arbitrary frequency points. We also present an analytical algorithm to compute the latter. Applications of this technique to multi-port synthesis as well as antenna matching are discussed. 10:50 11:10 Synthesis of multiport networks consisting of arbitrarily coupled resonators Guiseppe Macchiarella and Stefano Tamiazzo, Politecnico di Milano, Italy Abstract Multiport filtering networks are typically implemented with 2-port microwave filters suitably interconnected (multiplexers). In recent years there has been some interest in more general configurations for these networks, no longer made up of filters but instead realized with N resonators and p ports, arbitrarily coupled. From the synthesis point of view this is a formidable problem and further constraints must be specified for finding solutions of practical interest. In this talk the general synthesis problem is formulated in the general case, with reference to a suitable set of characteristic polynomials. It is first discussed the polynomials evaluation, highlighting how this is still an open problem (no analytical solution is available in the general case). The evaluation of the polynomials is however possible imposing additional constraints (concerning for instance the network topology, as in the case of star-junction multiplexers). An example of practical interest is then introduced, where the characteristic polynomials can be evaluated and the network topology doesn’t belong necessarily to multiplexers class. Finally a general family of canonical topologies is introduced for multiport networks and its derivation from the classical transversal prototype is illustrated. 11:10 11:35 Synthesis of multi-port Butler matrix with inherent filtering V. Tornielli di Crestvolant and M. Lancaster, University of Birmingham, UK Petronilo Martin Iglesias, ESA ESTEC, Noordwijk, The Netherlands Abstract The Butler matrix is a multi input/output network providing power and phase distribution. Common applications are antenna beam forming and power divider/combiner in multi-port power amplifiers (MPA). In some space applications it is necessary to cascade a bank of bandpass filters to the MPA in order to clean the near band of the spurious frequencies generated by the power amplifiers. A solution that incorporates the both the properties of a Butler matrix and the band-pass filter selectivity is reported here through a circuit based only on coupled resonators. The synthesis procedure proposed for such network is discussed and comparisons are made with regards the standard techniques for multi-port resonant networks. Some experimental measurements are given. 11:35 12:00 Special filter design for SIW-SMW implementation Smain Amari, Royal Military College, Kingston, Canada – Uwe Rosenberg, Mician Global Engineering, Bremen, Germany Abstract 12:00 12:25 Design of compact multiport filtering devices and subsystems Stéphane Bila, XLIM, Limoges, France Abstract Multiplexing and routing devices used in the payload of a communication satellite represent usually an important part of its mass and bulk. The purpose of compact devices is to improve integration with structures formed exclusively of coupled resonators, which eliminates all the connecting elements (manifold, waveguides and junctions). This talk will report on the design and the characterization of compact multiplexing and routing devices. Moreover, the talk will introduce some results on the co-design of filtering networks for optimized multibeam antenna systems.