Christian Person

Patch antenna adjustable in frequency using liquid crystal

The topic considered here is the design, achievement and test of a liquid crystal-based patch antenna. This device was realised in planar technology with low-cost foam substrate. Liquid crystal dielectric anisotropy permits frequency agility. Owing to technological difficulties of the foam, we used this dielectric property to adjust the shift of the antenna resonance frequency whenever required. The comparison of simulation and measurement data evidenced that frequency can be adjusted.

Wide band, high rejection and miniaturized fifth order bandpass filter on LCP low cost organic substrate

This paper deals with miniaturized and wide band bandpass filter. This filter is based on an original topology based on series and parallel resonators. Series resonators are realized using open-ended coupled lines and parallel resonator is implemented using an open-ended stub. This hybrid topology based on two kinds of stub leads to a twice more compact 5th order design compared to the conventional 5th order approach. Moreover, the use of resonators presenting different periodic behaviors implies additional transmission zeros and so, enhances the rejection of the filter. Liquid crystal polymer (LCP) is chosen by considering its low cost, good and stable RF performance over the frequency of interest and its ability to act both as a substrate and a package to obtain wide band filter. So, the combined use of this technology and this topology leads to a filter that presents very good electrical performances in a reduced occupied area. A compact wideband filter (2.38-4.2 GHz) with insertion loss of 1.2 dB and rejection has been designed by using a full-wave analysis and measurements are presented.

Ku-band microstrip diplexer based on dual behavior resonator filter

This report describes the design of original planar filters and of a diplexer based on dual behavior resonator (DBR) filter, and introduces measurement data. The specifications dealt with a limited frequency band in Ku-band where a high isolation is needed between Rx and Tx frequency bands. This study evidences the benefits of oversized DBR in particular for getting a high rejection level. Moreover, folding the oversized resonators allows one to keep constant the filter overall size. The first DBR filter for the Ku-band receiver is of 3rd-order with a central, folded, oversized and low-frequency stub; the second DBR filter for the Ku-band transmitter is also of 3rd-order with three folded, oversized and high-frequency stubs. Then, a diplexer as presented in Rhodes and Ievy (1979) and Matthanei et al. (1980) was realized from both filters as stated in Goron et al. (2003) and Tudosie and Vahlieck (2004).

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.

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.

Foam Micromachined Aperture-Coupled Antennas for V-Band Low-Cost Applications

In this paper, we present a novel micromachining approach for realizing 60 GHz foam aperture-coupled antennas. The foam is indeed an ideal antenna substrate provided by its electrical properties close to those of the air. At 60 GHz, the optimum foam thickness supporting the printed antenna must be about 400 mum, which is a technological obstacle due to the poor mechanical resistance of the foam. It has been surrounded by this new micromachining method. A single patch and a 2 times 4 antenna array have been realized and measured. They exhibit wideband bandwidth and excellent radiation efficiency. The gains are about 6.7 dBi for the single patch and 13 dBi for the 2 times 4 antenna array. These results demonstrate the great potential of foam substrate for 60 GHz antennas. To the best knowledge of the authors, this work is the first report of a low-cost, high gain and high efficiency 60 GHz foam aperture-coupled antennas.

Cross-Coupled Microstrip Dual Behavior Resonator (DBR) Filter

This paper deals with the design of cross-coupled microstrip dual behavior resonator (DBR) filters. It evidences the several ways of cross-coupling DBR filters to get, in particular, either a high level rejection or a flat group delay with a 4th-order filter. The two coupling structures described here are based on the DBR to allow a positive or negative cross-coupling effect. In order to validate this concept three different filters were realized on an alumina substrate. Simulation and experimental data are compared and discussed

A Wideband Circularly Polarized Patch Array for V-band Low-Cost Applications

In this paper, we present a 60 GHz low-cost circularly polarized patch array antenna which exhibits excellent axial ratio performances. The 3 dB axial ratio bandwidth has been measured to be about 11.25%. The 10 dB return loss bandwidth is up to 17% while the gain is about 10.2 dBi at 60 GHz. These results have been obtained by applying a sequential feeding array to an aperture-coupled truncated corner patch. To the best knowledge of the authors, this work is the first report of a 60 GHz low-cost microstrip aperture-coupled patch antenna which presents such performances.

High rejection C-band planar band-pass filter for a spatial application

This paper describes an original planar solution used to realize a high rejection planar filter in C-band for a given spatial application. Because of the very strong specifications for the filter, a classical topology such as a coupled-lines one was forbidden. The proposed solution is based on the use of Dual Behavior Resonators in which high frequency stubs are oversized to increase rejection. Low-pass structures are also integrated in order to suppress spurious resonances.

Dual-Behavior Resonator (DBR) C-band planar band-pass filter for a space application

This paper describes an original solution used to realize a C-band planar filter for a given space application. Because of the particular and strong specifications for the filter, a classical topology is forbidden. The proposed solution is, thus, based on the use of dual behavior resonators where high frequency stubs are oversized to increase the rejection at a specific frequency. Low-pass structures are also integrated in order to suppress spurious resonances. Two frequency planes with different local oscillators (LO) frequencies are studied. Simulated and experimental data are compared.