What is it about?

In this paper, new designs of optically transparent wearable antennas have been presented. The explored antennas have the excellent features of high flexibility, small size, low specific absorption rate (SAR) and high optical transparency. The proposed antennas are realised by utilising highly flexible, optically transparent and low-cost materials. For achieving compactness in antenna dimension and for improved transparency, square-ring-shaped radiator is used in the antenna design. To improve the efficiency and gain of the square-ring patch antennas, a new technique is proposed in this paper. The proposed technique utilises a strip line that connects the middle of the two opposite sides of the ring. Full ground plane is used in antenna design to reduce the back radiation. However, full ground plane reduces optical transparency. To elevate optical transparency without affecting antenna's back radiation significantly, a new technique of defected ground structure is investigated in this study. With this defected ground structure, the optical transparency is improved by about 6% without significantly compromising the SAR. The compatibility of the proposed antennas for wearable applications are investigated by examining the performances on flat and bent phantoms. Moreover, the robustness of the antennas are studied by subjecting the prototypes to multiple bending operations.

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Why is it important?

Optically transparent antennas are gaining popularity in wide range of applications, including healthcare technologies, vehicle communications, displays and photovoltaic solar panels. Compact and optically transparent antennas are good form of unobtrusive radiating elements. In many of these applications, it requires antennas having broadside radiation pattern. However, broadside radiating antennas utilizing microstrip technologies have ground plane underneath the radiating patch, which degrades the level of achievable optical transparency. This paper investigates defected ground structure and ring-patch radiator to utilize compact broadside antenna having high optical transparency and high front-to-back ratio. The explored design can be a potential candidate of unobtrusive antenna.

Perspectives

The investigated design in this paper is a novel approach of realizing unobtrusive antennas, especially for wearable technologies. The investigated defected ground structure can significantly improve the transparency without deteriorating the front-to-back ratio of the radiation pattern of the antenna. The utilization of ring-patch as the radiating element instead of solid patches is a novel idea of designing compact antennas with good electromagnetic performance, this technique is highly efficient when antennas are realized from lossy materials, e.g., flexible materials.

Abu Sadat Md Sayem
Macquarie University

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This page is a summary of: Increasing the transparency of compact flexible antennas using defected ground structure for unobtrusive wearable technologies, IET Microwaves Antennas & Propagation, August 2020, the Institution of Engineering and Technology (the IET), DOI: 10.1049/iet-map.2020.0495.
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