Substrate effect and structure optimization of fabric-based circularly polarized dipole antenna for radio frequency energy harvesting

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Radio frequency energy harvesting on textiles is seen as a method of enabling sustainable battery-free operation for wearable devices, while few works have clarified the influence of fabric properties on antenna performance. To prepare successfully a fabric-based circularly polarized antenna for radio frequency energy harvesting, this paper will clarify the effect of key fabric characteristics (such as dielectric properties and fabric thickness) on antenna performance by a finite element simulation. The simulated results showed the antenna resonant frequency is inversely proportional to the half square of the fabric’s dielectric constant, and the antenna radiation efficiency and gain are inversely proportional to the square of its dielectric loss tangent and thickness. Then, for the typical fabric substrates, the structure parameters of the existing circularly polarized antenna are optimized to work in the expected working frequency band, and the dominating structure parameter of the antenna in performance was identified. The optimized antenna prototype has excellent performance. The antenna has a bandwidth of 350 MHz and a maximum transmission distance of 190 cm. The received signal strength indication per unit area is 2.35 mW/cm ² and the output voltage is 1.19 mV/cm ² at a distance of 100 cm. It is concluded that the flexible size-minimized wide bandwidth circularly polarized radio frequency energy harvesting antenna screen-printed on fabric was derived from a commercial circularly polarized antenna with fiber-reinforced epoxy plate (FR4) substrate, and the critical geometrical and material parameters of the fabric substrate for this antenna performance as well as the affecting mechanism were identified.

Related collections

Most cited references 47

Record: found
Abstract: not found
Article: not found

Dual-Band Wearable Textile Antenna on an EBG Substrate

Shaozhen Zhu, Richard Langley (2009)

0 comments Cited 70 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: found

Is Open Access

Textile Materials for the Design of Wearable Antennas: A Survey

Rita Salvado, Caroline Loss, Ricardo Gonçalves … (2012)

In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented.