Benjamin Potelon

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.

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

Reconfigurable Planar SIW Cavity Resonator and Filter

A new reconfigurable frequency cavity compatible with planar technology has been designed, manufactured and measured. An original tuning solution is proposed, based upon the insertion of vertical capacitive posts integrated within SIW cavities. One extremity of each post is connected to a floating metallic ring, located on the substrate supporting the SIW cavity. The frequency agility is obtained once the metallic ring is connected to the ground plane by short-circuited the corresponding annular slot using surface actuators. Such combination of volumetric cavity and planar activation leads to reconfigurable filters with high Q values and simplified tuning control conditions

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.

Fabrication and characterization of a fully integrated biosensor associating microfluidic device and RF circuit

This paper presents the first results of the fabrication and characterization of a biological sensor based on two complementary parts. A microfluidic channel along with a micromachined stop-band filter are used to detect the type of fluid which flows beneath the electronic circuit. The tridimensional (3D) structure of the microstrip technology is integrated using SU8 material which thus supports the use of buried channels. Besides being a method without contact, this bio-sensor avoids evaporation, contamination, or label fixation. Changes to the cutoff frequency and attenuation allow us to differentiate three values of the salt in water concentration with a maximum variation of attenuation of 6.5%.

Ultra-compact X-band SIW filter in LTCC technology using high permittivity substrate for a space application

Substrate Integrated Waveguide (SIW) provides a better Q-factor compared with the other planar techniques. Its integration capabilities and fabrication cost are other benefits that make it attractive. But SIW filters are bulkier than their equivalents achieved in microstrip technology. This paper reports on the association of two solutions to reduce size and make SIW even more attractive: LTCC technology to stack cavities and high permittivity substrate. The objective is to demonstrate the possibility to build high performance X-band filter on a ceramics through a multi-layer approach. The solution is tested on a X-band-dedicated 6th-order filter with drastic specifications for space application.