A Multilayer Dipole-Type Element for Circularly Polarized Transmitarray Applications

A simple multilayer unit cell has been discussed for circularly polarized transmitarray applications in this letter. This element consists of three layers of identical substrates. Each substrate is printed by two sets of parallel dipoles of orthogonal directions on the opposite sides to realize a proper phase difference. The transmission coefficients have been studied to balance magnitude against phase difference. Then, the dipole dimensions are analyzed to obtain a satisfactory transmission. A transmitarray prototype of 137 elements has been designed, manufactured, and tested. The measurements present expected radiation patterns compared to the simulations. The measured result suggests a gain of 24.5 dBi with sidelobe level of -18.7 dB and cross polarization of -20.5 dB at 12.7 GHz, which is equivalent to a 38.9% aperture efficiency. The 1-dB gain bandwidth is 7.1%.