Abstract: A method for forming a radio frequency responsive target formed of a pattern of thin dipoles, each of which has a position and angular orientation within the pattern, which produce a composite analog radio frequency signal in response to an interrogating signal. A first metallic film layer is deposited on top of a non-conductive substrate, an etchant resistant pattern correspondent to the thin dipole pattern is deposited on top of the first metallic film layer, and a second metallic layer occupying the first metallic layer in at least one area without etchant is applied on top of the first metallic film layer. The etchant resistant pattern is removed to expose portions of the first metallic film layer, and the second metallic layer and the exposed portions of the first metallic film layer are etched simultaneously.

Abstract: A radio frequency automatic identification system detects targets which include a plurality of radio frequency resonators. Information is attributed to the target in accordance with the radio frequency response characteristics of the target, such as the resonant frequencies of resonators present, and/or the spatial locations within the target of the resonators. Preferred resonators include thin dipoles, which may be metallizations on a plastic film substrate. Information may be attributed to a target by fabricating the target with resonators disposed at locations to encode information in accordance with a predetermined encoding system; alternatively, resonators may be randomly disposed, and a translation code applied to convert the radio frequency information to particular information in a particular format. Readers for use in the system read the radio frequency response characteristics of a target in the near field of a radiating aperture which is illuminated by a radio frequency source.