Design of Frequency-Agile, Wearable Antenna Using High-Impedance Surface
Date Issued
2010
Date
2010
Author(s)
Shen, Shiou-Yi
Abstract
A frequency-agile, wearable antenna is presented in this thesis. To avoid the influences of the electromagnetic fields radiated on the user’s body while keeping the entire structure low-profile and conformal, we propose a frequency-agile high impedance surface (HIS), which is then integrated with the main radiator/antenna to suppress its backward radiation. The frequency agility is achieved by soldering varactor diodes between adjacent metallic patches that are periodically etched on a dielectric substrate with conductor backing. The operating frequency of the HIS can be tuned by changing the capacitance of the varactor diodes. For integration with the HIS, two broadband planar antennas, including a printed bow-tie antenna and a printed dipole array, are also presented in this thesis. By placing the printed antennas on the HIS respectively, two designs of frequency-agile, low-profile antennas with unidirectional radiation pattern are realized. Lastly, we bend the entire antenna conformally to a cylinder to simulate the situation that the antenna is attached onto a user’s arm. It is found that the performances of the antenna remain nearly unchanged. Moreover, the Specification Absorption Rate (SAR) of the antenna is also discussed. According to the simulation results, the SAR value is reduced significantly by using the HIS. Therefore, the proposed antenna may be suitable for use in body-worn wireless communication systems.
Subjects
Frequency agility
high-impedance surfaces
printed dipole antennas
wearable antennas
Type
thesis
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