Various embodiments of the present disclosure provide an antenna system including a first set of receive antenna elements and a second set of transmit antenna elements. Each receive antenna element is paired with one of the transmit elements. Paired receive and transmit antenna elements point in the same azimuthal direction, and the receive antenna element feeds its paired transmit antenna element. Each receive antenna element and each transmit antenna element has a phase center, and the phase centers of the receive and transmit antenna elements are all positioned substantially along the same axis. The receive and transmit elements are arranged in a phase-conjugate configuration such that, for each pair of receive and transmit antenna elements, those receive and transmit antenna elements are altitudinally spaced substantially the same distance from a plane through the antenna system.