Microstrip Antenna Array With a Beam Focused in the Near-Field Zone for Application in Noncontact Microwave Industrial Inspection

This paper presents a novel antenna having a beam focused to a small spot in the near-field zone which is intended for use in microwave industrial inspection. The array is implemented using broadband U-slotted microstrip patch-antenna elements and an integrated microstrip feeding network. Analogy with a dielectric lens is used to generate appropriate feeding coefficients for the elements of the array. The concept is demonstrated with two practical implementations having 300- and 126-mm focal distances. The measured results are presented and shown to be in good agreement with the predictions, validating the development concept.