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International audience; The demonstration of enhanced spatial control of nanosecond microwave plasmas generated by the time reversal plasma source is presented in this paper. This new microwave plasma source relies on the spatio-temporal control of the electric field inside an all-metal plasma reactor by modifying the waveform of a high power microwave signal. More specifically, it originally used the spatio-temporal focusing capabilities of the time reversal method to focus a high electric field in a small location. However, a parasitic microwave breakdown can still occur at sharp corners or wedges inside the cavity due to the local enhancement of the residual electric field during time reversal focusing. Thus, it is proposed to use the linear combination of configuration field method to improve field control inside the reactor. Its transient electric field shaping capabilities turn out to be a good candidate for the development of a low pressure microwave "plasma brush".

A preliminary study of the design of an electrically small plasma-based resonator using a localized surface plasmon resonance (LSPR) above 1 GHz is presented. Such a resonator is intended to be used to develop an electrically small antenna with frequency agility. This resonator consists of a plasma discharge confined in a hemispherical glass shell 3 cm in diameter on a ground plane. From 1 to 1.5 GHz, the plasma electron density required to achieve the LSPR must be between 0. $5\times 10^{11}$ and $1.4\times 10^{11}\mathrm{c}\mathrm{m}^{-3}$. Plasma losses are taken into account in this study and provide information on the required gas pressure. Typically for neon gas, the working pressure must be around 50 mTorr. A practical implementation using a miniature inductively coupled plasma (mICP) source is finally discussed.

This article presents the experimental work performed as part of the use of the non linear plasma-wave interactions in planar circuits to design microwave power limiters. A first non-resonant plasma-based microwave power limiter composed of a pre-ionized plasma discharge integrated into a 50 Ohms microstrip line has been experimentally characterized with steady-state and transient measurements. These results have been then confronted at each step to a resonant one using the same plasma discharge. This study highlights the effect of the resonance on the non linear plasma-wave interactions and its consequences on the behaviour and the performances of a plasma-based microwave power limiter.

BPID5187151.45 GHz. Once characterized, it exhibits 100 MHz data rate modulation capability. The encoded orbital quantum (or index modulation) only uses three states (for Q-PSK) and four array elements. The received signals also suffer from conventional OAM line of sight links drawbacks, especially OAM “cross-talk” which comes from OAM states non ideal orthogonality in the realized setup.

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.

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.

International audience; In order to clearly analyze the fundamental changes when dealing with OAM waves, we try to simplify a conventional point to point microwave link. The geometrical configuration is then reduced to face to face, co-axial, annular antenna arrays. Under assumptions of uncoupled elementary sources and ideal Beam Forming Network, the global link budget is derived from an original asymptotic development and analytically exhibits the topological charge effect. A new expression for antenna's Gain is then obtained, surprisingly increasing with the topological charge l. The specific decrease previously discussed by Tamagnone with respect to the distance is found again.

Full Paper — This paper deals with the proposition of a methodology for the design of reconfigurable antennas. First a basic review of reconfigurable antennas will illustrate the lack of a general method of design. Then the paper will discuss about the limitations of existing design methods and the way to overcome them. The restriction to MEMS switches on planar antennas is introduced. Finally some preliminary works are shown.

In this article, HIS-like resonators are proposed for mutual coupling reduction between the elements of a small array. First, a methodology is proposed for the design of HIS-like resonators. Then, a reference array made of two cavity backed patches working in L-band is designed. HIS-like resonators are then introduced in the array in order to reduce couplings between the patches in E-plane configuration. These two arrays are then manufactured with modular parts, providing the possibility to replace the patches and tune the HIS-like resonators resonant frequency. Simulated and measured S-parameters are illustrated, showing the capability of these structures to reduce significantly mutual couplings.

International audience; We have proposed and validated through simulations the possibility to interleave two pyramidal multi-band antennas. This new design enables to overcome bandwidth limitation problems as only one trap is now needed per radiating element on the radio navigation antenna. The feeding network is simplified as the two applications are now separated and polarizations can be defined independently for the two applications without significant impact on antenna design.

New multilayer configurations for dual and triple-band circularly polarized stacked microstrip antennas (CPSMA) are proposed. More than 7 dB simulated gain for both LHCP frequencies of satellite communication are obtained for the dual-band design and more than 5 dB for both LHCP and GPS RHCP for the triple-band design.

This paper presents a new way of modelling very large planar array antennas included in tridimensional structure. The aim is to match a rigorous method to a Floquet mode expansion. The first method is in fact a multi domain one (a domain decomposition method) based on electrical field integral equation -EFIE- and partial differential equation -FEM-. It describes electromagnetic behaviour of a single radiating element of the array. The description requires the use of generalised scattering matrices. Fields in radiation space are expressed by an Floquet modes combination with usual hypothesis. The array's environment is finally taken into account by asymptotic methods (PO and PTD) or rigorous method (EFIE). The accuracy and efficiency of our technique is illustrated by RCS diagram of a patch antenna placed in a canonical metallic box.

A novel topology of compact dual-band antennas is presented. Stubs are integrated in wire antennas for achieving dual-band feature and fractal geometry is used for compactness purposes. The design methodology is reported and an excellent agreement with the electromagnetic simulations is obtained

An original method is proposed which associates rigorous method (electrical field integral equation-EFIE and partial differential equation-FEM) with Floquet modes through multidomain formalism. Large array antennas can then be accurately analysed.

This paper presents a new family of components based on the MEMS and NEMS (nano-electromechanical system) concepts. They show very attractive properties for future wireless communications systems. The design of such components involves both electromagnetic simulations and mechanical and thermal modelling in order to get an accurate description of their electrical behavior.

This paper outlines the MEMS technology as a contender for the next-generation communications systems. Among the results, we can note that micromachined transmission lines feature very low loss and are now useable up to millimeter wave frequencies. Similar results are obtained concerning the micromachined filter which exhibits impressive performance in term of quality factor and insertion loss. MEMS switches are very promising devices as they will be able to replace a certain number of solid-state circuits, enabling better performances in term of loss, isolation, linearity and power consumption. Furthermore, these technologies are becoming to be involve in the realization of smart devices like micromachined oscillators, front ends, reconfigurable circuits or phase shifters.