Compact Folded Patch with Stretchable PDMS Substrate for On-Body RFID Applications

A compact folded patch is proposed for designing an on-body UHF RFID tag. Stretchable polymer such as PDMS (polydimethylsiloxane) has been employed as a substrate to increase the flexibility of the antenna, and it allows conformal mounting on human body. It has small footprint ($25\times 25\ \text{mm}^{2}$) and low profile (3 mm). For the proposed antenna design, its operating frequency can be easily tuned by adjusting the geometrical dimensions of the two shorting stubs. A ground layer has been incorporated into the design for achieving platform isolation. The proposed tag antenna has hemi-omnidirectional radiation patterns and it is able to achieve a maximum realized gain of −5 dBi when tested on a phantom that imitates human tissue.