Self-Progressive Near-Field Focusing 2-D Full Frequency Scanning Slot Array Antenna Based on Ridge-Gap Waveguide

A millimeter-wave self-progressive near-field focusing (NFF) 2-D full frequency scanning ridge-gap waveguide slot array antenna is proposed in this article. In the proposed array antenna, the adjacent linear NFF leaky-wave antennas (LWAs) are connected end to end in a double layer folded structure to construct a self-progressive phase shift feed network. Thus, the desired high phase progression in the design of the 2-D frequency scanning is provided by the linear NFF LWAs themselves with the superposed propagation length. As a result, the NFF 2-D frequency scanning performance can be achieved without increasing antenna area based on the proposed high-density self-progressive feed network, which is built by applying the ridge-gap waveguide. The proposed antenna prototype is fabricated through the computer numerical control (CNC) machining process and is verified by the experiment. The test information of the object under test in the near-field region can be directly obtained with a certain frequency band, showing good promise in the near-field detection application.