Compact Flexible Wideband Antenna for On-Body Electromagnetic Medical Diagnostic Systems

A flexible on-body antenna that is compact, unidirectional, and wideband is presented for electromagnetic (EM) biomedical diagnostic systems. To achieve a low operating-frequency band with compact size, an annular ring antenna is loaded with a capacitive gap, a shorting post at its end, and a shorted circular parasitic element. The antenna is designed and fabricated on a purposely built, highly flexible, low-loss, low-cost room-temperature-vulcanizing silicone (RTV) substrate with a tremendously compact size of 0.055\lambda _{0}\times 0.055\lambda _{0}\times 0.009\lambda _{0} , where \lambda _{0} is the free-space wavelength at the lowest frequency of 0.55 GHz. The antenna exhibits a measured bandwidth of 0.55-3 GHz at different locations of the human body. The measured near-field radiation patterns demonstrate that the antenna attains unidirectional near-field radiations with more than 10 dB front-to-back-ratio. The received dominant signals of the antenna also exhibit a low distortion level with more than 90% fidelity factor. The achieved features of the proposed antenna confirm its merits for EM biomedical diagnosis applications.