Simple Dual-Band Polarization Rotator with Independent Control of Transmissive and Reflective Modes

This study proposes an independently controlled polarization rotator with transmissive and reflective capabilities operating in two different frequency bands. The proposed independently controlled transmissive and reflective polarization rotator (ICTR-PR) unit cell consists of four metal layers separated by three substrates. The transmissive polarization rotator mode is realized by two strips (receiving strips) on the top layer, which are connected with two vias through circular holes inside the ground plane to two 90^◦ rotated strips (transmitting strips) on the bottom layer. The reflective polarization rotator mode was produced by connecting another pair of strips on the top layer to a microstrip line located in the middle layer. Properly adjusting the length of each strip allows both transmissive and reflective features to be independently controlled. The proposed rotator exhibits dual-frequency band resonances at 7.7 and 9.48 GHz for reflection and transmission responses, respectively. Furthermore, a high polarization conversion ratio (PCR) of more than 80% was achieved for both modes. A prototype was fabricated and measured to validate the simulation results. A good agreement between the experimental and simulated results was obtained.