A Broadband VHF/UHF-Loaded Dipole Antenna in the Vicinity of a Human Body

A broadband dipole antenna with a very simple low-cost mechanical structure is proposed. This dipole of the height of 173 cm with inductor/resistor (LR) loading circuits is designed to operate in the frequency range of 30-512 MHz - hence a 17:1 bandwidth (178%). By choosing the optimized location of LR loads, the radiation pattern is controlled. Meanwhile, the VSWR 1:3.5 is adjusted by an input matching circuit, tuning a number of LR loads, and using a transmission line transformer. The impedance matching is better than -6.5 dB in whole frequency bandwidth. The antenna gain is gradually increased from -20 dBi at 30 MHz to -2 dBi at 512 MHz. The manufactured prototype is presented along with its measured characteristics which map well onto software simulated counterparts. The antenna is considered to be used in portable applications. Therefore, the simulations and the measurements are conducted near the human body. A simple model of the adult human body at the frequency band of the proposed antenna is used, which helps to study the effects of the human on the antenna performance. Moreover, the electromagnetic exposure on the human body is investigated. Experimental evidence is presented to verify the conclusion.