Millimeter-Wave Slot Array Antenna Front-End for Amplitude-Only Direction Finding

A novel millimeter-wave (mm-wave) amplitude-only direction finding (DF) antenna front-end is proposed and experimentally demonstrated based on multiport leaky-wave antennas (LWAs). The multiport LWA is realized using an array of $N$ linearly polarized slot antennas. Each slot antenna is engineered to produce a beam pointing along a specific direction, exploiting the beam scanning law of LWAs. Realizing progressively shifted beams angularly in space by controlling the slot geometry of each antenna, the multiport LWA becomes sensitive to a large finite angular sector. Using this architecture, a unique mapping between the angle of arrival (AoA) and the port locations is achieved. Using detailed full-wave simulations, the DF operation of the slot-based LWA is successfully demonstrated for several examples involving single and multiple signals illuminating the antenna. It is demonstrated that the AoA can be determined by measuring the received power at each of the ports and the known radiation patterns of the LWAs. The DF antenna front-end is demonstrated experimentally at 60 GHz using a ten-port slot array antenna fabricated using substrate integrated waveguide (SIW) technology and tested in various incoming signal scenarios.