Wearable Quarter-Wave Folded Microstrip Antenna for Passive UHF RFID Applications

Table 1

Antenna requirements and specifications.

Operational frequency band	920–926 MHz ISM band in Australia (regulated by Australian Communications and Media Authority).
Impedance	The WISP has a measured input impedance of 78 + 16j Ω after an on-chip matching network. A good impedance matching is crucial for maximum performance.
Read range	The tag should have a suitable read range to properly track the human. The current dipole has a read range of 2.5 m; it is desired to increase this range. It is also desirable to have a low directivity, that is, semidirectional pattern, for good angular coverage.
Materials	The antenna must be flexible so that it can be subject to bending and can be worn by a human.
Reliability	The tag should not be easily detuned because of its location on or near the human body.