Dual-Band Frequency-Reconfigurable Wearable Antennas for UHF Radio Band Applications

A dual-band multifunctional body-worn textile antenna is proposed. The antenna has the capability to tune its resonance frequency at its lower band, which aims for applications in the upper range of the ultrahigh-frequency (UHF) radio frequency band. At the same time, it independently operates with a fixed resonance frequency at 2.45 GHz for general communications or data transfer purpose. The antenna concept is first proposed with a single feeding port design, which achieves a frequency tuning range of 60% in the lower band. Then, an alternative configuration with two independent feeding ports is demonstrated, which is able to efficiently use the fixed frequency at the higher band. This second antenna is optimized to have an isolation of at least 15 dB between its two ports for operation with two coexisting transceiver systems. At the lower band, the fractional tuning range is approximately 37%. The two antennas are fabricated and measured to validate the design concepts.