The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper introduces an adiabatic Floquet modes expansion to design modulated metasurface (MTS) antennas. In these antennas, a MTS implements periodically modulated impedance boundary conditions to transform a bounded surface wave into a radiative leaky wave. A Floquet Wave expansion locally matched to the impedance boundary conditions well describes fields and currents on the MTS. This expansion...
This paper concerns the analysis of fields and currents on modulated metasurfaces (MTSs) and the synthesis of MTSs implementing a given field distribution. The work herein described has been developed to set up an effective design process for modulated MTSs realizing antennas with customizable pattern. Here we give a brief description of the process for the analysis, synthesis and implementation of...
This contribution addresses the use of reconfigurable modulated metasurfaces (MTSs) for the realization of electronically scanning antennas without the use of phase shifters. Different approaches can be used to electronically control the average equivalent impedance or the modulation period of the modulated MTS.
In this paper, we discuss an extension of the Floquet-wave theory to curvilinear locally periodic boundary conditions. The local periodicity of curvilinear impedance surfaces is exploited to adiabatically apply the Floquet Wave theorem to fields and currents. We show that this extension allows for a good description of the interaction between the currents and the curvilinear boundary conditions. Based...
In this paper, we describe an efficient method for the full-wave simulation of printed antennas based on metasurfaces whose texturing is realized by means of elliptical patches. The method is based on the fast solution of an integral equation discretized by using the method of moment with only two entire domain basis functions for each elliptical patch. The two-dimensional version of the Fast Multipole...
In this paper, a procedure to calculate the dyadic impedance (or admittance) Green's function for a grounded layer of LCs is briefly presented. To validate the theoretical procedure, an example of dispersion calculation of a grounded layer of LCs is presented, showing excellent agreement with the simulations made with a commercial software.
This paper proposes a rigorous approach for the analysis of the surface-to-leaky wave transformation by means of a spatially modulated metasurface. The physical insight provided by the results of this analysis allows for accurately designing the metasurface to improve the performances of modulated metasurface antennas. Numerical results relevant to a metasurface antenna with a tapered aperture distribution...
This paper describes the operating principle of a modulated metasurface antenna (MoMetA) capable to provide both Right-hand and Left-hand circularly polarized boresight radiation at Ku-band. This antenna is based on the interaction between two cylindrical-wavefront TE and TM surface wave (SW) modes with perfect polarization and phase balances. Feeding system requirements and characterization of the...
Realizations and measurements of broadside-beam circularly polarized anisotropic metasurface antennas are presented. The validity of the design methodology proposed in a previous paper is here experimentally demonstrated by developing a 28-dBi transmitting antenna and a 22-dBi receiving antenna for space-to-ground links at X-band. High polarization purity is obtained by using a simple vertical (i...
This paper presents a generalization of the Oliner's method used to investigate the guided modes supported by a Sinusoidally-Modulated Surface Reactance (SM-SR). In its original paper, Oliner applied the procedure to the case of a scalar and impenetrable impedance sheet in free space; in this work, this approach has been extended to find the guided mode configurations (both leaky and surface waves)...
This paper presents an efficient and accurate approach for the analysis of anisotropic metasurfaces (MTSs) consisting of elliptical patches printed over a grounded slab. The formulation resorts to an analytical expression of the currents excited on the elements of the periodic texture to define a reduced spectral MoM procedure with only two basis functions. This procedure can be used to effectively...
The suppression of undesired surface waves on a reference array antenna resorting to a low-cost wide-band EBG surface is investigated experimentally through measurements of embedded element radiation patterns. An EBG frame around the array aperture is used to reduce back and side radiation while narrow EBG strips are placed in-between columns or rows of antenna elements to mitigate blind spots. Measurement...
A metasurface is a thin metamaterial layer characterized by unusual reflection properties of plane waves and/or dispersion properties of surface/guided waves. Metasurfaces can be realized at microwave frequencies by printing a dense periodic texture of small elements on a grounded slab, with or without shorting vias. These structures have been widely used for realizing electromagnetic bandgap (EBG)...
In this work an innovative method for the characterization of dispersion in metamaterials is presented. The attention is focused on structures realized by stacks of planar periodic surfaces. The analysis procedure subdivides the artificial material into its constituent planes, performing a full wave analysis of the individual planar periodic structures, and uses analytic formulas from Bloch theory...
This paper demonstrates the design and the analysis of a novel type of horn antennas with a potentially higher directivity. The idea is to replace one plate of an H-plane horn antenna with a plate that has specially designed surface impedance. In our case we generated the surface impedance variation that corresponds to a Luneburg law, thus obtaining the Luneburg lens effect and consequentially increasing...
Advances in spiral circularly polarized surface wave antennas are presented. Such antennas are designed by using the concept of modulation of surface reactance. The surface impedance is reconstructed by printing a dense texture of sub wavelength metal patches on a grounded dielectric slab. The final devices are planar thin antennas with a simple layout and feeding. Numerical results are present and...
This work proposes an innovative method for the characterization of dispersion in metamaterials consisting of stacks of planar periodic surfaces. The analysis procedure separates the artificial material into its constituent planes, performs a full wave analysis of the individual planar periodic structures and uses analytic formulas from Bloch theory to determine the dispersion characteristics of the...
This paper demonstrates the properties of an H-plane horn antenna with its characteristics improved using the principle of variable surface impedance. Modifying the surface boundary conditions on one surface of the parallel plate structure is possible by using printed patches of variable size. By doing so, surface impedance profile which corresponds to Luneburg law can be realized. Luneburg lens designed...
This paper presents results for an array of patch embedded in an EBG. The EBG surface is composed by short-circuited microstrips densely coupled each other through interlocked branch stubs. With respect to a conventional mushroom surface, this structure exhibits a better space-wave decoupling performance. The experimental results demonstrate decoupling till 38 dB in both planes for patches separated...
We present here the analysis of surface wave modes supported by anisotropic high-impedance boundary conditions realized artificially by irregular dense patches printed on a grounded slab. A method for the determination of a quasi-analytical forms of this anisotropic boundary conditions is illustrated on the basis of the pole-zero matching method.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.