Electronically Beam-steerable Dual-band Reflectarray for Satellite Communications

This paper presents a novel continuously beam-steering dual-band, dual circularly polarized (CP) reflectarray. The dual band operation of the reflectarray is obtained by using the interleaved circularly polarized triangular patches as the radiating elements. Each of the patches has two proximity feed lines that are electromagnetically coupled to a branch line coupler, where the phase shifters are integrated. The phase shifter is realized by using a new type of high-frequency tunable dielectric materials, Lead Niobate Pyrochlores $Pb _{n} Nb _{2}O_{5+ {n}}\,($ PN). By controlling the applied voltage, the dielectric permittivity of the PN material can be changed. This characteristic is utilized to the design of tunable dielectric capacitors, which is placed between the ground and the signal line of a Co-planar waveguide (CPW) transmission line. To validate the design concept, X-band passive antenna prototype was designed, fabricated and measured. Preliminary results on the designed phase shifter and tunable dielectric materials are also presented in this paper.