Investigation of Virtual Array Antennas With Adaptive Element Locations and Polarization Using Parabolic Reflector Antennas

Abstract

A novel multi-phase center parabolic reflector antenna is investigated that utilizes a single hardware system to displace the antenna phase center location electronically in any direction, while generating identical broadside secondary radiation patterns at the far-field region to convert the reflector antenna into a virtual array. The primary feed is a dual-mode circular waveguide operating at the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> type modes. The combination of these modes with different polarizations, amplitude ratios, and phase differences are considered. It is shown that the phase center location of the antenna can be displaced from the physical center of its geometry by changing the excitation amplitude and phase of each mode, and more importantly by employing different mode orientations. This results in a virtual array antenna with element locations that can be displaced in any direction, depending on the polarization of each mode, by a simple signal processing procedure without mechanically moving the antenna itself. The antenna developed using this technique has potential applications as a transceiver antenna in precise positioning systems, radars with moving platforms, and virtual smart antennas. The operating frequency is 10 GHz. The proposed multi-phase center virtual antenna concept is verified experimentally exhibiting excellent agreement with the numerical results.