Laurent Liard

Static and dynamic control of limiting threshold in plasma-based microstrip microwave power limiter

Static and dynamic control of the limiting threshold in a very low-loss plasma-based microstrip power limiter is investigated in order to prevent receivers from being threatened by high-power microwave (HPM). An analytic model of the microstrip circuit is proposed to derive the influence of its design on the limiting threshold of the microwave power limiter. Experimental results are in good agreement with those expected. Finally, an original approach to allow discrete limiting threshold tunability is presented and validated experimentally.

Modeling and experimental measurements of a tunable microstrip resonator using plasma discharges

In this paper, we suggest the use of a cold plasma as tunable material inside a microstrip resonant cavity. Plasma dielectric constant can indeed be moved to values below 1 to tune its resonant frequency. DC plasma analysis were conducted and integrated into classic electromagnetic solvers to investigate tuning abilities. Numerical simulations are consistent with experimental results and make this original tuning techniques viable for high power applications.

Antena impresa invertida reconfigurable en frecuencia a base de una microdescarga de plasma

espanolEn este articulo se propone el estudio de una antena impresa invertida reconfigurable en frecuencia a base de una microdescarga de plasma. La idea es generar una microdescarga controlada en corriente al interior de una cavidad situada entre el plano tierra de la antena y su conductor principal, cuyo objetivo final es de modificar la frecuencia de resonancia de la antena. El interes en la utilizacion del plasma como elemento reconfigurable es su tiempo de conmutacion y, sobre todo, su capacidad de manejo de altas potencias. Se demostro de manera teorica que la reconfiguracion en frecuencia de una antena tipo parche, con una microdescarga en su cavidad, es dependiente de la densidad electronica del plasma. Ademas, se implemento un prototipo de antena impresa invertida reconfigurable en banda X integrando una microdescarga, la que tuvo excursion en frecuencia medida de 180 MHz. EnglishThis paper proposes the study of an inverted microstrip plasma-based reconfigurable antenna. The scope is to generate controlled microplasma inside the cavity between the antenna ground plane and its main conductor. This plasma will modify the resonant frequency of the antenna. The interest of using a plasma discharge as an active reconfigurable element is its switching time and mainly its capability of handling high microwave power. It was demonstrated, theoretically, that the reconfiguration frequency of a microstrip patch antenna with a microdischarge in its cavity, depends on the electron density of the plasma. Furthermore, a prototype of an X-Band inverted microstrip patch antenna, which integrates a microdischarge, was implemented. The measured frequency excursion for this prototype was 180 MHz