Cédric Quendo

Detection of micro-cracks on metal surfaces using near-field microwave dual-behavior resonator filters

The aim of this paper is to demonstrate that micro-cracks at the surface of metals can be detected and imaged by using near-field micro-wave resonators. It deals with two novel sensors: a first-order dual-behaviour resonator (DBR) filter and a first-order DBR filter with an open-ing in the ground plane. Measurements were mainly carried out on a stainless steel mock-up with several EDM (i.e. manufactured by Electron Discharge Machining) rectangular surface notches presenting widths between 0.1 and 0.3 mm and depths between 0.5 and 3 mm. The results presented here show the high sensitivity of the DBR probes and their ability to differentiate between notches of different depths and notches of different widths.

An original topology of dual-band filter with transmission zeros

This paper reports on a new topology of high-performance dual-band filters. This topology is derived from the Dual Behavior Resonator (DBR) filter. The resulting resonator is directly dual-band. It allows the control of two bandpasses separated by a transmission zero to ensure a high rejection level between them. Moreover, two other transmission zeros are located on either side of the two bandpasses. The possibilities offered by this structure are discussed and measurements are presented to validate the method.

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.

Synthesis of capacitive-coupled dual-behavior resonator (CCDBR) filters

The two topologies and associated syntheses described here are dedicated to the design of capacitive-coupled dual-behavior resonator filters. The technique is based on the coupling of adjacent dual-behavior resonators (DBRs). The aim is to control the spurious resonances associated to classical DBR filters. In the first coupling technique, the inverter is replaced with an equivalent scheme composed of a set of three capacitors, i.e., a positive capacitor associated with two negative ones in parallel on both sides. The second technique relies on the same principle, but two equivalent schemes are moved along each stub of the resonators; the capacitance is then calculated by considering the position of the coupling effect on the stub and the value of the inverter. In both cases the synthesis is totally defined. In order to validate this concept, capacitive-coupled DBR filters and classical filters were designed on alumina substrate so as to compare simulation and experimental data

Bandwidth and central frequency control on tunable bandpass filter by using MEMS cantilevers

This paper deals with a tunable bandpass filter topology which controls independently and simultaneously both the central frequency and bandwidth. This tunable filter results from the association of MEMS cantilevers, used as variable capacitors, with an original passive topology. The latter is based on dual behavior resonators (DBRs), each of them is constituted of low- and high-frequency open-ended stubs. The associated filter electrical response is characterized by tunable frequency transmission zeros. A millimeter bandpass filter with central frequency and relative bandwidth tunability of about 10 and 75%, respectively, is presented.

Design of a Substrate Integrated Waveguide (SIW) Filter Using a Novel Topology of Coupling

We report on a new topology of coupling between substrate integrated circular cavities designed to produce particular filtering functions through combination with the classical iris-based coupling. This coupling is achieved by a grounded coplanar line etched at the top of cavities. This topology was used to realize a Ku-Band third-order filter, whose synthesis, electromagnetic simulation with HFSS, and experimental performances are presented here.

Integration of optimized low-pass filters in band-pass filters for out-of-band improvement

We propose an original structure for the design of high performance filters with simultaneously controlled band-pass and band-reject responses. The band-reject response is controlled due to the integration of low-pass structure. Thus, the spurious resonances of the band-pass filter are rejected up to the low-pass filter ones. In this way, we have to optimize the response of the low-pass structure in order to control the out-of-band response of the band-pass filters.

Synthesis of dual behavior resonator (DBR) filters with integrated low-pass structures for spurious responses suppression

This paper deals with a rigorous synthesis of dual behavior resonator (DBR) filters with integrated low-pass filter for spurious response suppression. The basic low-pass filter consists in an L-C-L structure associating two transmission lines and an open-ended stub. After full definition, the synthesis is validated from comparisons between simulation- and experimental-data acquired with some third-order filters designed on alumina substrate

Design of Ku-Band Filter based on Substrate-Integrated Circular Cavities (SICCs)

This paper proposes several topologies of filters based on substrate integrated circular cavities (SICCs). SICC works on TM modes and the benefits of this technology are mainly an increased quality factor and a better design flexibility. Filters are made from cylindrical cavities integrated into a planar substrate and are fed by microstrip lines through coupling slots. Cavities are inter-coupled by irises. One-order, second-order and third-order filters are presented. Preliminary measurement data are compared to those from simulations performed with a 3-D electromagnetic structure simulator. These filters rely on the SICC concept, whose principle is explained hereafter

Design of narrow-band DBR planar filters in Si-BCB technology for millimeter-wave applications

This paper discusses a method used to design planar bandpass filters for millimeter-wave applications in U- and W-band frequency ranges. For technical reasons, these filters have to be implemented on silicon-based technology. So as to decrease the insertion losses levels inherent in silicon substrate, we propose a thin-film microstrip-like technology implemented on a benzocyclobutene layer. In addition, a dual-behavior resonator-based filter topology enabled us to fit a hardened specification. In association with this new topology, we employed an automated design procedure that combines both circuit and full-wave simulations. It is based on a statistical sensitivity study performed by design-of-experiment analysis.