A Novel Reflection-Type Polarization Convertor Design Using Connected Orthogonal Tightly Coupled Dipole Arrays

Herein, we design a polarization convertor (PC) using two orthogonally polarized, tightly coupled dipole arrays (TCDAs) connected in cascade, of which one is used for the reception of incident waves and the other is used for their transmission. The operation of the PC is elucidated via a cascading equivalent circuit of unit cells of orthogonally polarized TCDAs. The critical role of vertical metal strips (VMSs) with regard to wide-angle insensitivity is discussed. Moreover, it is found that the undesirable common mode occurs under oblique incidence and its frequency is related to the size-to-height ratio of the unit cell. To demonstrate the performance of the proposed PC, a 40 $\times40$ array structure is fabricated and measured using the Naval Research Laboratory (NRL) arch method. The simulated bandwidth range is 2.06 to 14.54 GHz (7.06:1) for a polarization conversion ratio (PCR) $\ge80$ %, and the measured bandwidth range is 1.68 to 14.51 GHz (8.64:1) for a PCR $\ge72$ % at an incident angle of 10°. At an incident angle of 40°, the simulated and measured bandwidths are 2.15 to 14.13 GHz (6.57:1) and 2.43 to 13.87 GHz (5.71:1) for a PCR $\ge80$ %, respectively.