A single sided RF tag suitable for use for electronic article surveillance comprises a tuned circuit formed on one side of a substrate. Provided by a deposited first conducting layer which comprises an inductive coil, which behaves as an antenna and is electrically connected to a first
capacitor plate and a connection means to connect to a second conducting layer. A
low dissipation factor
dielectric layer is deposited onto said first conducting layer. A second conducting layer comprising at least one
capacitor and a connection means to electrically connect to the first conducting layer is deposited on the
dielectric layer. The second
capacitor plate is substantially co-located above the first capacitor plate, to form the capacitor. The capacitor and coil together form a resonant circuit. The circuit pattern for the first and second layer may be formed by known
metal printing techniques, such as, for example the use of a catalytic seed layer which is deposited by a pattern
transfer mechanism into the circuit pattern. Alternatively the circuit pattern may be formed by standard photo-
lithography etch techniques to reveal a circuit pattern from a metallised surface. The tag will preferably incorporate known methods of fusing to deactivate or detune the tag, to permit removal of articles from an enclosed area. The substrate may further include a second RF tag tuned to an alternative frequency on the opposite side of the substrate. Alternatively a plurality of tags may be built up in successive
layers on one or both sides of the tag.