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Theory, design, realization and measurements of an X-band isoflux circularly polarized antenna for LEO satellite platforms are presented. The antenna is based on a metasurface composed by a dense texture of sub-wavelength metal patches on a grounded dielectric slab, excited by a surface wave generated by a coplanar feeder. The antenna is extremely flat (1.57 mm) and light (less than 1Kg) and represents a competitive solution for space-to-ground data link applications.Index Terms-Leaky wave antennas, surface impedance, holographic antennas.

This two-part sequence deals with the formulation of an efficient method for the full wave analysis of large phasedarray antennas. This is based on the method of moments (MoM) solution of a fringe integral equation (IE) in which the unknown function is the difference between the exact solution of the finite array and that of the associated infinite array. The unknown currents can be interpreted as produced by the field diffracted at the array edge, which is excited by the Floquet waves (FW's) pertinent to the infinite configuration. Following this physical interpretation, the unknown in the IE is efficiently represented by a very small number of basis functions with domain on the entire array aperture. In order to illustrate the basic concepts, the first part of this sequence deals with the two-dimensional example of a linearly phased slit array. It is shown that the dominant phenomenon for describing the current perturbation with respect to the infinite array is accurately represented in most cases by only three diffracted-ray-shaped unknown functions. This also permits a simple interpretation of the element-by-element current oscillation, which was recently described by other authors. The second part of this paper deals with the appropriate generalization of this method to three-dimensional (3-D) arrays.

Abstract-A novel type of leaky-wave antenna is presented. Differently from previously reported leaky-wave antennas, it is characterized by a constant beam direction over a very wide range of frequencies. The radiation originates at a slot etched at the interface between air and a dense dielectric, which is shaped to form a cylinder of elliptical cross sections of decreasing dimensions. Two prototypes have been designed, manufactured, and tested. The measurements are in very good agreement with the expectations, demonstrating the potentials of the leaky lens concept to realize integrated transmitters or receivers that are extremely broadband and directive.Index Terms-Broad-band antennas, leaky waves, lens antennas, slot antennas.