Fractal slot loaded compact wearable button antenna for IOT and X-band applications

A Fractal geometry based compact multiband wearable button antenna with wider bandwidth, less cross polarized radiation in both the orthogonal planes and low specific absorption rate (SAR) at all the resonating bands is presented in this article. The antenna comprises a slotted circular patch printed on the top of a circular piece of low-cost FR-4 substrate with radius 9.6 mm fed through coaxial feeding mechanism. Multiband behavior is achieved by the implementation of fractal based circular slots up to third iteration whereas the loading of two additional circular slots offers significant improvement in both bandwidth and gain. Radii of the circular slots are optimized properly in HFSS to attain the desired performance. On-cloth and on-body analyses of the proposed antenna are also carried out to investigate the effect of interaction with cloth and body materials on the antenna performance. The antenna offers multiband response covering the operating bands 4.1-4.64 GHz, 7.19-8.03 GHz and 8.85-9.67 GHz with very low SAR value ensuring less electromagnetic interaction with body tissues. The fabricated prototype shows comparable measured values with the simulated ones.