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Dispositifs accordables en radiofréquence : Exemples d'un adaptateur d'impédance accordable et d'un filtre passe-bas contrôlé optiquement

Abstract : In the framework of higher need of tunable RF device in the telecommunication industry, the various technological options presently available need to be compared and benchmarked. To this purpose, this work has been dedicated to the design of tunable compact microwave devices. Two functions have been evaluated: a tunable impedance matching network at 1 GHz and a low-pass filter optically controlled at 6 GHz.
In the first study, a compact narrow band impedance matching network has been designed in hybrid technology, employing coplanar waveguide transmission lines and surface mounted components. This device is a Π-structure with tunable components made of varactors in series with inductors. Simulations and measurements have been found in good agreement. Measurements have been carried out using a new approach. They show that complex impedances with magnitudes varying from 6Ω to 1kΩ can be matched at 1GHz, with a 50% bandwidth.
A low pass filter has then been designed in the second study. It consists in a structure whose periodical variation of the characteristic impedance is introduced by the repetition microstrip line pattern. Its tunability has been introduced by additional periodical ground defects masked or not by illumination Thanks to analytical formulas derived from the coupled mode theory, the device scattering parameters excluding harmonic response (only one bandgap) have been extracted for a specific characteristic impedance variation. A prototype of this low pass filter has been fabricated in cleanroom, it demonstrates the tunability of this device.
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https://tel.archives-ouvertes.fr/tel-00342727
Contributor : Christophe Hoarau <>
Submitted on : Friday, November 28, 2008 - 12:36:12 PM
Last modification on : Wednesday, March 10, 2021 - 9:50:02 AM
Long-term archiving on: : Monday, June 7, 2010 - 10:07:42 PM

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  • HAL Id : tel-00342727, version 1

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Christophe Hoarau. Dispositifs accordables en radiofréquence : Exemples d'un adaptateur d'impédance accordable et d'un filtre passe-bas contrôlé optiquement. Sciences de l'ingénieur [physics]. Université Joseph-Fourier - Grenoble I, 2008. Français. ⟨tel-00342727⟩

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