Wideband Antenna Systems for Millimeter-Wave Amplitude-Only Direction Finding

Two-antenna systems for wideband amplitude-only direction finding (AODF) are demonstrated. Tapered slot antennas (TSAs) are integrated into two flush-mounted configurations to achieve desired performance over 18-45 GHz range. The first system is made of two TSA elements embedded inside an absorptive cavity. Fed by a 90° hybrid, this phased-array topology supports two squinted beams required for AODF. The second system is made of two identical TSA elements physically squinted off boresight to produce required beams without beamforming. This allows each TSA element to be embedded in a separate nonabsorptive and shaped cavity for much improved AODF including widened field of view, higher gain, better dynamic range, and eliminated sidelobes. The system implications for the use of the proposed antenna front ends in terms of bearing errors to amplitude imbalances and receiver noise are also discussed. The construction of both antenna systems is disclosed, and experimental results closely resembling and therefore verifying theory are obtained.