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This work presents a novel dichroic cell for multi-band reflector antenna systems that has two different configurations using a novel resonant element formed by rings connected with tuning stubs. The case study presented shows the design of a symmetrical cell using two resonant elements in both faces of the dichroic cell and the design of a non-symmetrical cell using one novel resonant element in one face of the cell and a single ring in the other face. These two configuration allows to perform different topologies of dual band feeds.

In this work, the authors compare two designs of reflectarray antennas made of two different types of elements. One of the reflectarray designs is intended to generate a collimated beam and the other is intended to generate a contoured beam. In order to produce these radiation patterns, in one case three coplanar parallel dipoles are used as reflectarray elements, and in the other case stacked square patches are used as reflectarray elements. The results obtained indicate that the collimated beam and shaped beam reflectarrays made of parallel dipoles have a good bandwidth performance, which is comparable to that of the collimated beam and shaped beam reflectarrays made of stacked patches. However, the reflectarrays made of parallel dipoles achieve the broadband goal with a manufacturing process that is easier and cheaper than that required by the reflectarrays made of stacked patches.

In order to design printed reflectarray antennas within reasonable CPU times, fast and accurate numerical tools for the analysis of periodic multilayered structures are required. In this work the spectral domain method of moments based on multilayered Green's functions (SDMOM-MGF) is applied to the analysis of periodic arrays of three parallel dipoles printed on the same interface of a multilayered medium. Basis functions with edge singularities are used in the approximation of the current density on the dipoles. The set of three parallel dipoles is a very convenient element in the design of refelectarray antennas since it leads to simplifications in the manufacturing process while retaining important design features such as phase range and bandwidth. In this work, the results obtained with the SDMOM-MGF in the analysis of periodic arrays of three parallel dipoles are compared with results provided by the electromagnetic simulator CST, and with measurements carried out in a waveguide simulator. Good agreement is found between the three sets of results, and it is shown that the CPU times required by the results obtained with the SDMOM-MGF are about two orders of magnitude shorter than those required by CST.

Planar arrays are a very interesting option to substitute reflector antennas because of their well-known characteristics of low profile, potential low cost, reliability and flexibility in achieving contoured beams and multiple beams with a simple planar geometry. Suitable solutions using planar antennas for space applications have been proposed using reflect-arrays with countered beams and multibeam. Another proposed solution consists of transmit arrays. In this case, the antenna acts as a lens [1]. This consists of a periodic planar array having two patch antennas connected by a line. One element receives the signal from –z direction and the other transmits the signal in the +z direction. By a proper selection of the phase delay in the connection line, the phase distribution in the transmitting array can be adjusted. In an equal output phase configuration the transmitting array behaviour would be similar to the obtained with a parabolic reflector, having the advantage of removing the feed blockage.

A shaped-beam reflectarray based on aperturecoupled elements is demonstrated as central station antenna for Local Multipoint Distribution System (LMDS) in the 10.10- 10.70 GHz band. The antenna must cover a 60° sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the squared patches, in order to achieve the phase distribution synthesized in the previous step. A reflectarray antenna has been designed for vertical (V) polarization. A breadboard has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns.