Over-the-Air Test of Dipole and Patch Antenna Arrays at 28 GHz by Probing them in the Reactive Near-Field

A test concept for millimeter-wave antennas and antenna arrays using metallic probes inserted in the reactive near-field of the single radiating element is presented. Demonstrated for patch antennas and planar dipole antennas operating at 28 GHz, the transmission line probes are designed to avoid de-tuning of the antenna feed-point impedance. When applied to antenna arrays, the unwanted coupling to neighboring elements is shown to be suppressed by more than 10 dB, compared to the coupling with the antenna radiator under test. Therefore, parallel probing of several array radiator elements becomes possible. Additional aspects of the proposed technique are discussed.