Radio frequency identification (RFID) tags on thin substrates of less than 0.3% of a wavelength are presented. The tag antennas are formed of balanced lines wrapped around conducting rectangular patches and separated by a gap. The elements are above ground planes which lie entirely, or partially, beneath them. Good conjugate matches are offered to the RFID chip and read ranges close to the maximum quoted for a given system are achievable with these designs, even when attached to lossy or conducting bodies.
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