International audienceThis paper deals with the design of scalar metasurface antennas able to radiate a well-polarized beam in the far field or near field zones. The equivalent electric current over the metasurface is used to derive design equations to generate the desired field pattern based on the scalar impedance condition. In particular, it is shown that scalar metasurfaces can be used to generate linear and circular polarizations for a fixed pointing direction in the far field by properly changing locally the scalar impedance boundary condition. In addition, they can also be used to generate normal polarized Bessel beams in the near field region. Several solutions are presented at 20 GHz, with different polarizations and feeders developed in the framework of a two-year research project financed by the French space agency (Centre National d'Etudes Spatiales, CNES). Measurements and full-wave results validate the proposed approach

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Wide-angle coverage, fine angular resolution and low-power consumption are key characteristics of millimeterwave (mm-wave) short-range wireless systems, such as access points in fifth-generation (5G) cellular networks and automotive radars. In this paper, we present a 60-GHz switched-beam antenna system addressing all these requirements. It consists of two identical parallel-fed arrays of 8 slots, each fed by a passive pillbox beamformer. A switch network comprising four singlepole-multiple-throw (SPnT) switches excites one of the two arrays at a time and selects the radiated beam. The whole system is fully-integrated in a multilayer low temperature co-fired ceramic (LTCC) module. The antenna covers a scan range of about ±39 • in one plane using eleven beams, between 57 GHz and 66 GHz. The proposed architecture enables the simultaneous achievement of continuous coverage (beam crossover levels of about-3 dB) and of low sidelobe levels (SLLs). Dedicated numerical tools are used for a preliminary design of the antenna. The design procedure, the technological development and the experimental results are discussed in detail. Index Terms-switched-beam antenna, millimeter-wave antennas, 5G, 60-GHz communications, low temperature co-fired ceramic (LTCC).