Miniaturized Wearable Fractal Antenna for Military Applications at VHF Band

Abstract

Abstract-This paper presents the design and development of Koch fractal dipole antenna for wearable applications at 450 MHz. Common jeans cotton is used as a flexible substrate material having a dielectric constant of 1.6 for the design and fabrication of the proposed antenna. Increasing the number of iterations increases the number of sections, which eventually results in 32% reduction in size. Size miniaturization is obtained using second iteration Koch geometry with the antenna bandwidth of 10%, and the return loss of −25 dB is achieved under the flat condition. The investigations are to characterize the antenna not only in flat condition, but also under different bendings and crumpling conditions. The proposed Koch fractal antenna is close to the proximity of the body, and the absorption of electromagnetic power on human body is also examined. It is found that the Specific Absorption rate (SAR) is much below a safety level of 0.119 W/kg and hence suitable for wearable applications.

Exposure Assessment to Radiofrequency Electromagnetic Fields in Occupational Military Scenarios: A Review

“…The peak SAR 1g resulted equal to 0.0252 W/kg and 0.175 W/kg for f = 1.575 GHz and 915 MHz, respectively, both at 1 W input power. Poonkuzhali et al [ 33 ] modelled an antenna on a human arm operating at 1 W input power at 450 MHz and found a peak SAR equal to 0.1427 W/kg. An E-shaped patch wearable textile antenna was considered in [ 34 ] and it was positioned on a torso model; in this study, the peak SAR 1g for f = 1.85 GHz and f = 2.45 GHz, with the input power of 1 W, resulted equal to 0.54 W/kg and 0.35 W/kg, respectively.…”

Solar Cell Integrated Wearable Patch Antenna on Artificial Magnetic Conductor for On-Body and In-Body Communications

“…For high performance radio LAN (HIPER-LAN) applications, the radiation performance of copperbased and Zelt-based conductive fabric-based wearable patch antennas [24] aided by polyester fabric substrate was investigated. Under bending and crumpling conditions, the copper foil koch fractal wearable dipole antenna in the very high frequency (VHF) band (430 MHz-475 MHz) for military applications [25] and the ring resonator wearable patch antenna [27] at 5.8 GHz aided with a common jeans cotton substrate were investigated. A parametric study was demonstrated on the rectangular textile patch antenna [26], which was made from both copper and nickel-plated polyester fabric with a denim substrate for ISM band wireless body-area network applications.…”

Human Exposure Assessment to Wearable Antennas: Effect of Position and Interindividual Anatomical Variability

“…Since the wearable devices are often integrated into the user's clothing, the wearable antenna must be lightweight, thin, easily integrated into the garment, and it should not obstruct the user's movements [7]. Moreover, the position of the antenna relative to the human body is a crucial aspect since, because of that, the wearable device may vary from its original setting and consequently, its performances could change.…”