Jean-François Favennec

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

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.

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

Planar tri-band filter based on dual behavior resonator (DBR)

This paper reports on the application of dual behavior resonators to design triband filters. The principle is briefly presented by considering monoband, dual-band and triband filters. A circuit is proposed by using an approximate synthesis. Then, a hybrid (electromagnetic / circuit) simulation is performed to take into account the parasitic effects induced by the junction discontinuities and to allow a fast triband optimization in the same time. An example of layout with associated simulated and experimental results is proposed.

Ka-band Lange coupler in multilayer thick-film technology

A 3-dB Ka-band Lange coupler was implemented in a multilayer thick-film technology, which avoids the drawbacks of planar technology, e.g. bonding-wires and the limitation of the coupling level induced by the minimal resolution of the slot between the coupled lines. The coupler was realized and measured by using 50-Ω thick-film resistors as terminations. Finally, the electrical performances exhibited by the proposed coupler proved to be good with a coupling level of 4.2 dB at the central frequency, a return loss greater than 15 dB and isolation greater than 20 dB in the coupler passband.

Miniaturized C-Band SIW Filters Using High-Permittivity Ceramic Substrates

This paper introduces an effective way to build efficient miniature C-band filters using high-permittivity ceramics. The objective was to evaluate the feasibility of such filters using commercial electromagnetic simulators and a conventional fabrication process. For the demonstration, the substrate integrated waveguide (SIW) technology was chosen. Compared with planar solutions, this configuration offers good quality factors and good electrical performances as a consequence. However, its dimensions are large, leading to unacceptably large footprints for many applications. The solution proposed in this paper is based on a ceramic substrate with a permittivity of 90, which allowed us to work with shorter wavelengths. In comparison with a standard alumina substrate (permittivity εr= 9.9, this approach makes it possible to reduce the footprint up to nine times. Two prototypes were realized on a Trans-Tech ceramic substrate (thickness = 635 μm, εr = 90, and tanδ = 9 · 10-4. The first prototype is a folded sixth-order SIW filter including a cross coupling combining coplanar waveguide probes and a thin microstrip line on an InterVia substrate. The second one is a folded eighth-order SIW filter without cross couplings. Here, we compare the sixth-order prototype with an identical one built on alumina. The eighth-order filter, which had no alumina counterpart, is a potentially useful alternative for situations where complex technological steps must be avoided.

Development of a microsystem based on a microfluidic network to tune and reconfigure RF circuits

This special issue presents devices and the results of a tunable microwave microsystem associating RF circuits and microfluidic components. A channel is buried inside the substrate of a microstrip waveguide. This channel is located beneath a resonant stub. With this configuration a microfluidic passive tunable filter can be fabricated. Dielectric fluids are used to disrupt the electric field in a microstrip structure and thus modify the effective permittivity of the substrate. In this work, a notch filter is realized with an open-ended quarter-wavelength stub placed on top of a hollow SU-8 structure. This structure offers two advantages: channels can easily be fabricated and a reduction of SU8 losses. The filter shows a good performance; the initial cut-off frequency of 25 GHz shifts more than 20% when deionized water is used in fluidic channels. And the shape of RF function is kept throughout the range.

Design of Bandpass Filter Based on Hybrid Planar Waveguide Resonator

This paper presents a new concept of bandpass resonator based upon the association of planar and substrate integrated waveguide technologies. The selectivity, control of rejection, and ease of design are significantly enhanced by the hybrid planar waveguide resonator compared to the classical substrate integrated waveguide resonators. The hybrid planar waveguide resonator is built from the association of two elements: a substrate integrated circular cavity and a transmission line. When these two elements are connected together, they permit the occurrence of the pole and the transmission zero of the hybrid planar waveguide resonator. This paper describes and discusses the design procedure for n th-order filters. This procedure relies on an iterative process between synthesis equations and a graph. Electrical performances and particularly Q factor are brought to the fore through the realization of a single resonator. The design procedure is then validated through the realization and measurement of a C-band second-order filter. Finally, a third-order filter in the Ku -band is designed, realized, and measured.

C-Band Multilayer Bandpass Filter Using Open-Loop Resonators With Floating Metallic Patches

This letter presents a fourth-order quasi elliptic bandpass filter based on a multilayer technology. Thanks to the use of the third dimension, multilayer technology appears as a very convenient solution when a high coupling is required. This led us to use a coupling coefficient-based approach to design a very compact filter through the association of open-loop resonators and floating metallic patches to elevate coupling.