Serge Verdeyme

Direct electromagnetic optimization of microwave filters

This article explores an optimization procedure for microwave filters and multiplexers. The procedure is initialized by a classical filter synthesis based on a segmented electromagnetic synthesis that provides the basic dimensions of the structure. The optimization loop, which combines a global electromagnetic analysis and a coupling identification, improves the structure response compared to an empirical optimization.

Synthesis and design of asymmetrical dual-band bandpass filters based on equivalent network simplification

Although the synthesis of symmetrical dual-band bandpass filters has been studied, little seems to be known about the general asymmetrical case. In this paper, a procedure for the synthesis of general asymmetrical dual-band bandpass filters implemented with inline dual-mode cavities is proposed. The inline architecture, as well as the asymmetrical nature of the response, lead naturally to the choice of an extended box topology or generalizations of the latter. It was recently shown that these topologies possess the property of multiple solutions, meaning that the related coupling matrix synthesis problem admits several solutions. On one hand, this multiplicity offers some flexibility to the designer, but on the other hand, working with multiple solutions may lead to ambiguities during the tuning process. Our procedure takes the best of both worlds: using the list of equivalent coupling matrices, simplifications of the original topology can be obtained by canceling some particular couplings. The locations of cancelled couplings are chosen so as to preserve the electrical response and to provide some hardware simplifications. It is also shown that the resulting simplified topology no longer has the multiple solution property, therefore solving ambiguity problems. The procedure is detailed and demonstrated on two examples.

Mutual Synthesis of Combined Microwave Circuits Applied to the Design of a Filter-Antenna Subsystem

A mutual-synthesis approach is presented for the design of subsystems combining two microwave circuits. In this paper, we are focused on subsystems combining a filter and an antenna. In a first step, the methodology consists of synthesizing the global subsystem, which realizes both filtering and radiation functions, with respect to overall specifications. Considering circuits interactions within the subsystem, the resulting constraints are distributed optimally between the two circuits. The latter mutual synthesis then leads, on one hand, to a set of optimal impedances for their connection and, on the other hand, to the corresponding ideal characteristics of each circuit. A solution can then be selected by carrying out a compromise between the simplicity of achieving the characteristics of each circuit and the performances and compactness of the subsystem. In a second step, the circuits are designed independently with respect to the synthesized characteristics. Compared to a classical synthesis approach, where circuits are synthesized independently with respect to a common reference impedance (generally 50 or 75 Omega), the proposed mutual synthesis allows to simplify the global subsystem since interactions between the two circuits are considered and used optimally. The technique is illustrated with the design of a filter-antenna at Ku-band.

Ceramic Layer-By-Layer Stereolithography for the Manufacturing of 3-D Millimeter-Wave Filters

Three-dimensional (3-D) ceramic stereolithography has been developed and used to manufacture RF devices using periodic structures. To our knowledge, it is the first time that zirconia and high-performance Ba3ZnTa2O9 ceramics are used with that process to manufacture high unloaded quality factor resonant structures and bandpass filters working in the Ka-band. A theoretical study on the performances of periodic arrangements of high-permittivity structures has been carried out and has led to the manufacture of a high unloaded quality factor cavity and narrow three-pole filter (1% bandwidth) measured at a working frequency of 33 GHz

Coupled Pade approximation-finite element method applied to microwave device design

In this paper, a fast and rigorous analysis method is presented, combining the Pade approximation and a finite element method. The method is applied to the design of two microwave devices: a narrow band bandpass filter and a broadband microwave module. The accuracy of this approach is demonstrated by the good agreement between the coupled Pade approximation-finite element analyses and the standard finite element ones, and also between the coupled Pade approximation-FE analysis and the experimental filter response.

Method of spurious mode compensation applied to manifold multiplexer design

This paper outlines an hybrid circuit/electromagnetic process dedicated to manifold design which take into account spurious modes in the frequency band. The procedure is applied to design an experimental Ku-band triplexer. The multiplexer model and the compensation method are described. Good agreement between theoretical results and measurements ones demonstrates the efficiency of the procedure.

Fast and accurate C.A.D. of narrow band waveguide filters applying an electromagnetic segmentation method

This paper outlines a segmentation method dedicated to filter design applying a finite element software. This method is particularly efficient, simple, accurate and fast to design dual-mode band-pass filters using simple models. Any numerical electromagnetic software can be used to realize the segmentation. At the end of the procedure, all the dimensions of the filter (cavities and irises) are known. The filter can be built without any modification of these dimensions during the tuning. The different stages of the procedure are described in this paper. Experimental results show good agreement with theoretical ones.

Synthesis of Vertical Interdigital Filters Using Multilayered Technologies

Taking advantage of multilayer technologies, a vertical evolution of the interdigital topology is proposed with its associated synthesis method. In order to validate this filter topology, a 4-pole filter, centered at 10 GHz, and an 11-pole filter, centered at 6 GHz, have been designed and fabricated using low-temperature co-fired ceramic (LTCC) technology. Two other multipole filters have also been designed showing a large surface reduction with respect to equivalent interdigital filters. LTCC technology has been chosen for fabricating the filters, but the proposed topology can also be implemented with other multilayer technologies.

Innovative Shielded High

This letter presents a compact design of a shielded high unloaded Q dielectric resonator. The main interest of this work is the use of the three-dimensional stereolithography process to manufacture innovative ceramic radio frequency devices. Thus, a resonator, its support, and the surrounding cavity is manufactured in one part out of alumina by that process. The measured structure exhibits an unloaded Q of 3900 at 11.88GHz and is free of spurious modes over a 3-GHz range

Q

A novel and compact design of a dual-band filter with widely separated passbands is proposed. Applications of such a device can be found in systems where a single device is responsible for both transmission and reception. The proposed filter is composed of resonators working on two distinct modes. The proposed dual-mode structure offers a good rejection of unwanted resonances, producing a widely separated dual-band response. The idea is demonstrated with the design of a four-pole filter comprising two dual-mode structures and the concept is verified experimentally by the measurement of a fabricated prototype. Finally, a six-pole filter is proposed, showing the possibility of designing higher order filters.