The design and experimental validation of a wide scanning dome antenna with reduced profile is presented. The antenna is based on the combination of a planar phased array with limited scanning capabilities and a dielectric lens which allows to broaden the field of view. The angular variation of the scan loss can be almost arbitrarily designed if no constraint is imposed on the size of the dielectric lens. However, the focus of the paper is on the size minimization of the dome as required for applications where the form factor is critical. Therefore, a lower boundary of the height of the dome is derived and imposed as a design constraint. The antenna is analysed using in-house ray tracing and physical optics software tools. It is shown that, when the array is combined with the dielectric dome, a significant directivity enhancement can be achieved for wide scanning. A demonstrator of the lens is designed, manufactured and combined with an available phased array working in Ku-band. The experimental tests confirm the theoretical predictions, validating the analysis tools, and show a scanning range of 70° in all scanning planes over a 15% bandwidth. The directivity is enhanced by approximately 2 dB at the limits of the scanning range compared to the stand-alone illuminating array. The active element pattern is rotationally symmetric, thus, the radiation performance is almost independent on the scanning plane. Moreover, the dielectric lens allows to preserve the cross-polarization performance of the illuminating array without adding a significant contribution.

One planar 18x18 cm2 reflectarray prototype, capable of generating adjacent pencil beams with orthogonal circular polarizations (CP) in Ka-band (19.2-20.2GHz), has been designed, manufactured and measured as a proof-of-concept to demonstrate the possibility of beam separation in dual CP applications. The prototype exhibits main beams pointing at elevation angles of 16.7° and 21.3° for left-hand CP and righthand CP respectively. A 1.5dB gain variation and 66efficiency is achieved in the frequency band 19.2-20.2GHz for a design center frequency of 19.7 GHz. These results will be useful for future work involving the design of multi-spot dual CP and dual band planar reflectarrays.

A synthesis method for the design of large planar array antennas with phase-only control is here presented. The synthesis is based on the use of Zernike polynomials, as global basis function for the phase, to reduce the number of optimization variables with respect to the number of elements of the array. Invasive weed optimization (IWO) is applied to polynomial coefficients’ optimization to circumvent non-linearity and local trapping issues typical of phase-only problems. The periodicity of the array factor is exploited to reduce the optimization to a Voronoi cell of the grating-lobes’ lattice and non-uniform meshing is introduced to best adapt the control stations to the beam shape requirements. The technique is applied to the design of shaped beams for continental coverage from geostationary satellites.

The design, manufacturing, and testing of a 0.65-meters doubly curved polarization selective reflectarray for dual-band multiple spot beam communication satellites in Kaband is presented. The configuration is based on a single-offset reflectarray consisting of rotated split hexagonal-loop dipole elements printed on a single-layer substrate. For RHCP, the reflectarray scans the reflected beam half a beamwidth in one direction, and for LHCP, the reflectarray scans the reflected beam half a beamwidth in the opposite direction. This is achieved in both Tx (17.7-20.2 GHz) and Rx (27.5-29.3 GHz) frequency bands. Using a feeding array with 22 feeds, 41 beams over the Earth can be generated, permitting to cover the entire Earth coverage from a geostationary satellite employing the 4-color frequency/polarization re-use scheme using only two reflectarrays while maintaining single-feed-per-beam operation. The reflectarray has been manufactured and measured, and an excellent agreement between simulated and measured patterns is obtained, thus validating the proposed concept.

This contribution describes the design of a multibeam parabolic reflectarray to produce two adjacent beams per feed in orthogonal Circular Polarization (CP) simultaneously at transmit (Tx) and receive (Rx) frequencies in Ka-band. The Variable Rotation Technique (VRT) has been applied to reflectarray cells based on two types of resonant elements, which makes it possible to provide orthogonal beams at Tx and Rx, as well as to implement an in-band optimization procedure to reduce the cross-polarization. A 90-cm parabolic reflectarray has been designed, manufactured and tested to produce multiple adjacent beams in RHCP and LHCP at both 20 and 30 GHz. The results are satisfactory and validate the concept of generating two spaced beams in orthogonal CP by a single feed, changing the polarization of the beam between Tx and Rx. This concept can be suitable for multispot satellites in Ka-band, enabling to halve the number of onboard antennas and feeds.