A Multiantenna System With High Isolations for Millimeter-Wave Sensing

This letter presents a multiantenna system with several superiorities of compact structure, high isolation, and low profile, which can be applied as a millimeter-wave sensor. The proposed multiantenna system includes three probe-fed patch antennas, which are integrated in a limited aperture (1.2·λ0 × 1.2·λ0, λ0 is corresponding to the center frequency at 24.1 GHz). Although the antennas are tightly arranged, high-isolation performance between each two antennas (> 25 dB) is achieved by rotating the antennas by 45° and introducing an X-shaped decoupling structure. Including with the impedance matching layer for measurement, the total thickness of the proposed antenna system is just 0.056·λ0, which is convenient for the integration with radio-frequency integrated circuits. The impedance matching layer is designed as a coplanar-waveguide-transition between the feed probe and the connector for multiantenna measurement in such a compact space. For demonstration, the proposed multiantenna system is fabricated and measured. The good agreement between measurement and simulation guarantees the promising application of this design for radar sensing.