A Broadband Double-Layer Transmitarray Antenna Based on Polarization Conversion Elements

A broadband double-layer transmitarray antenna (TA) is proposed in this letter. In order to obtain broadband performance in a double-layer structure, we use a "receiving- transmitting" (RX-TX) structure instead of a double-layer frequency selective surface. The elements of the new TA are composed with metal layers and dielectric substrate. Both the metal layer are connected by a metallized via and etched with orthogonal slots. The RX and TX layers work without interfering while converting the linearly polarized incident wave into orthogonal polarization. Phase compensation can be achieved by changing the direction and length of the microstrip meander ling. Then, a broadband TA is designed. Considering the simplicity of the design, we sequentially selected eight phase states at 45 degrees intervals for phase modulation. The measured maximum antenna gain is 24.5 dBi. The center frequency is 10 GHz. The measured 1 and 3 dB gain bandwidth are 18.7% and 29.4%, respectively. The maximum aperture efficiency is 51%.