Multifunctional Microstrip Array Combining a Linear Polarizer and Focusing Metasurface
Although microstrip reflectarrays/transmitarrays have been extensively studied in the past decades, most previous designs were confined to monofunctional operations based on either transmission or reflection. In this communication, we propose a scheme to design multifunctional arrays that can simultaneously exhibit the functionalities of a reflectarray and a transmitarray on the basis of the appealing feature of a polarizer we discovered (i.e. constant phase difference between its cross polarization transmission and copolarization reflection within a broadband) To demonstrate the proposed scheme, we designed and fabricated a multifunctional device comprising a 15 x 15 array of twisted complementary dual split ring resonators, each carefully designed to exhibit the desired transmission phase satisfying a parabolic distribution. Feeding the device by a Vivaldi antenna at its focus, we numerically and experimentally demonstrated that our system functioned as a directive emitter working in a transmission/reflection mode for cross polarization/copolarization radiation at low/high frequencies, and it can radiate directively in both directions with different polarizations at intermediate frequencies. The half power beamwidth of the array antenna was ~15deg, which is 40deg narrower than that of a bare Vivaldi antenna. Moreover, the gain was higher than 13 dB in all cases studied, which is at least 7 dB higher than that of the Vivaldi antenna.
IEEE Transactions on Antennas and Propagation