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International audience; In this paper, a detailed study and the optimization of a Negative Impedance Converter (NIC) circuit are presented to increase the bandwidth of a passive metasurface. The design and optimization procedure take into account the biasing and the effect of the transistors. The optimization ensures that the load can be realized with passive components.

International audience; This paper presents a metasurface reflector, characterized with a 0° reflection phase, which can be tuned to operate at any frequency within the band [1.1 – 1.7 GHz] and in two orthogonal polarizations independently. The proposed metasurface, based on a double layer of periodic metallic patches and varactors, behaves like an artificial magnetic conductor (AMC). By varying the capacitance values of the varactors, the positions of the resonant frequencies of the AMC can be tuned in real time. The proposed solution offers the possibility to overcome the narrow band characteristics of AMC structures and to control the two orthogonal polarizations independently.

This paper presents an anti-jam GPS array. The antenna is comprised of 4 small size radiating cavities filled with two stacked patches and a series of dielectric substrates and a foam layer. The main features of the antenna are low profile shape and low inter-element coupling. The antenna design is compatible with high impedance surface (HIS) insertion, which can potentially improve the anti-jam capabilities of the array by providing further inter-element coupling reduction.

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.