Comparative study of reflectarrays based on cells with three coplanar dipoles and reflectarrays based on cells with three stacked patches

Reflectarray Antennas for Dual Polarization and Broadband Telecom Satellite Applications

“…2 = I-For these geometrical parameters, the magnitude and phase of co-polar reflection coefficients at normal incidence in Tx (11.3 GHz and 12.6 GHz) and Rx (14.00 GHz) frequencies are shown in Fig. 2(b) and (c) as a function of the dipole lengths for X-polarization A similar response is obtained for Y-polarization In spite of the presence of 5 dipoles, the results do not show a significant improvement with respect to those obtained for three dipoles [21]. In fact, only two resonances and a range of phase-shift around 400° is obtained for the lower frequency.…”

“…The cross-polarization only increases in the area close to the dimensions / D2 = 9.5 mm, l c = 12.0 mm, due to a spurious resonance. We have observed that this type of resonances also appear in other reflectarray elements, as in the case of three parallel dipoles and stacked patches [21], for a certain combination of dimensions and angle of incidence (out of the principal planes). For these combinations of dipole lengths and angle of incidence, which should be avoided in a practical design, some energy is transferred from co-polar to cross-polar components.…”

“…It has been checked by e.m. simulations that the cross-polarization introduced by this type of reflectarray elements is lower when the parallel dipoles are symmetric in the periodic cell, at the cost of reducing the degrees of freedom (independent dipole lengths). Four coplanar parallel dipoles have not been chosen because they only provide 2 optimization variables for each polarization in a symmetric configuration, as it happens in the case studied in [21] where three parallel dipoles were used. In the following, an odd number of laterally coupled dipoles will be assumed, the lateral dipoles being symmetric with respect to the central dipole, in order to keep low levels of crosspolarization.…”

“…Different broadband reflectarray elements have been proposed, including stacked patches of variable size [12]- [13], aperture coupled elements [5], modified Malta crosses [8] and multi resonant elements on a single substrate layer [9]- [11]. In all these configurations, the element bandwidth is improved by adding more degrees of freedom to control the phase in the reflectarray cell, and by adjusting the associated geometrical parameters [21].…”

Optimized Periodic MoM for the Analysis and Design of Dual Polarization Multilayered Reflectarray Antennas Made of Dipoles

“…The set of parallel dipoles is an alternative multiresonant reflectarray element showing a flat slope of the phase as a function of dimensions and a phase range that well exceeds 360° [7]- [12]. The single layer element based on parallel dipoles has been used to design reflectarray antennas with performances that are similar to those attained with the element based on stacked patches for single polarization applications [10]- [12]. For dual polarization applications with frequency reuse, one can arrange two different sets of orthogonal dipoles in two levels of metallization so that the first set controls one polarization, and the orthogonal set controls the other polarization.…”