ANALYSIS OF PHASE-FOCUSED NEAR-FIELD TESTING FOR MULTIPHASE-CENTER ADAPTIVE RADAR SYSTEMS

Airborne or spaceborne radar systems often require adaptive suppression of interference and clutter. Before the deployment of this adaptive radar, tests must verify how well the system detects targets and suppresses clutter and jammer signals. The radar antenna diameter can be large and thus the conventional far-field test distance is impractical to implement. This paper discusses the theory and simulations of phase-focused near-field testing for adaptive phased array antennas. With near-field source deployment, standard phased-array near-field phase focusing provides far-field adaptive nulling equivalent performance at a range distance of one aperture diameter from the adaptive antenna under test. Both main beam clutter sources and sidelobe jammer sources are addressed. The test sources are assumed to be bandlimited noise sources radiating from dipole antennas. The phased array antenna elements analyzed are one-half wavelength dipoles over ground plane. Bandwidth, polarization, array mutual coupling, and finite array edge effects are taken into account. Numerical simulations of an adaptive antenna that has multiple displaced phase centers indicate that near-field and far-field testing can be equivalent.