Two-dimensional transmit arrays for polar over-the-horizon radar

Two-dimensional (2-D) transmit arrays offer many advantages over traditional over-the-horizon radar (OTHR) arrays, including the capability to steer and mitigate auroral clutter, a clutter type prevalent in polar operation, in all azimuth and elevation directions. The approaches of previous studies on OTHR 2-D transmit arrays are considered suboptimal, but it can be shown that the 2-D array is an effective OTHR transmitter when operated in an appropriate manner. A reference system derived from publicly available information on an operational OTHR array is used as a benchmark to compare the performance of various 2-D OTHR transmit systems with respect to effective isotropic radiated power on target, sidelobe levels, and elevation selectivity.