Fast Analysis of Stop-Band FSS Integrated with Phased Array Antennas

This paper presents a method for the efficient analysis of multilayer frequency selective surfaces (FSSs) integrated with phased array of open-ended waveguides. The method is based on the assumption that all the periodic surfaces are arranged on the same spatial lattice (of arbitrary shape). The whole structure is represented as an equivalent multi-mode transmission line network, where each interface is characterized by an equivalent Generalized Scattering Matrix (GSM), computed through a fullwave analysis. To reduce the computational effort of the analysis a fast adaptive interpolation algorithm for the scattering matrix entries is included

Metasurface Antennas: New Models, Applications and Realizations

This paper presents new designs, implementation and experiments of metasurface (MTS) antennas constituted by subwavelength elements printed on a grounded dielectric slab. These antennas exploit the interaction between a cylindrical surface wave (SW) wavefront and an anisotropic impedance boundary condition (BC) to produce an almost arbitrary aperture field. They are extremely thin and excited by a simple in-plane monopole. By tailoring the BC through the shaping of the printed elements, these antennas can be largely customized in terms of beam shape, bandwidth and polarization. In this paper, we describe new designs and their implementation and measurements. It is experimentally shown for the first time that these antennas can have aperture efficiency up to 70%, a bandwidth up to 30%, they can produce two different direction beams of high-gain and similar beams at two different frequencies, showing performances never reached before

Dual circularly polarized broadside beam antenna based on metasurfaces

Design details of a Ku band metasurface (MTS) antenna with dual circularly polarized (CP) broadside radiation is shown in this work. By means of the surface impedance tensor modulation, synchronized propagation of two transversal magnetic (TM) and transverse electric (TE) surface waves (SWs) is ensured in the structure, which contribute to the radiation in broadside direction by the generation of a CP leaky wave. The structure is implemented by elliptical subwavelength metallic elements with a cross-shaped aperture in the center, printed on top of a thin substrate with high permittivity (AD1000 with a thickness of λ0/17). For the experimental validation, the MTS prototype has been excited employing an orthomode transducer composed by a metallic stepped septum inside an air-filled waveguide. Two orthogonal TE11 modes excited with ±90° phase shift in the feed couple with the TM and TE SWs supported by the MTS and generate RHCP or LHCP broadside beam. Experimental results are compared with the simulation predictions. Finally, conclusions are drawn

A luneburg lens designed by using a variable artificial surface

This paper presents an innovative method for the design of planar lens inside parallel waveguide using Fakir's bed of nails substrate (FB) [1]. The FB is used to modulate the surface impedance on a boundary of the waveguide in order to obtain the desired refraction index for the guided wave. The method is general and can be used to design any kind of planar lens

Lens effect in parallel plate waveguide realized by using a metamaterial surface

This paper presents an idea for designing a planar Luneburg lens inside a parallel plate waveguide by using an artificial metamaterial surface. In the present article, the surface is realized by a bed of nails. By modulating the heights of the nails, a variable impedance is obtained on one boundary of the parallel plate thus obtaining an equivalent desired refraction index for the guided wave. The method can be used for designing other kinds of planar lenses

Flat leaky-wave lenses

Dielectric leaky wave antennas based on modulation of surface reactance are presented. Changing the reactance surface pattern changes the radiated field properties. The operational principle is simple and promise to be suitable for reconfigurable surfaces. In this optic two devices based on a grounded dielectric slab with variable thickness are shown together with relevant numerical result

A pole matching method for the analysis of frequency selective surfaces

In this work, a pole matching method is presented for the analytical reconstruction, from full-wave data, of the scattering properties of frequency selective surfaces (FSS). This method allows one to synthesize the scattering response of an FSS from the identification of a few parameters, which exhibits a weak dependence with respect to the angle of incidence. This property implies that the full-wave analysis of the FSS can be performed for a limited set of incidence directions, from which the overall response can be obtained by a simple and numerically efficient algorithm. The final outcome is an analytical form for the scattering matrix which may be conveniently used in ray-tracing algorithms, based on local flat-surface approximations of curved FSS

Numerical issues in the analysis of large BoR antennas involving dielectric and metallic parts

The aim of this paper is to investigate some numerical issues involved in the Moment Method solution of the radiated field by axially symmetric antennas (Body of Revolution antennas) that are very large in terms of the wavelength. The approaches found in the literature are reviewed and an improvement is introduced for decreasing the computational cost when the integrands are singular and oscillatory