Influence of Relative Humidity on Textile Antenna Performance

Abstract

The next generation of garments is sensorized, and therefore requires an adapted wireless communication tool such as a textile antenna. However, when integrating this flexible antenna into clothing, stable and reliable functioning in the operating frequency range is required. Climatic changes, especially altering relative humidity, might influence the textile antenna performance. This effect has to be taken into consideration when selecting the textile materials that comprise the antenna. A variety of antenna substrate materials has been investigated in this paper. It was found that antennas based on materials with a small moisture regain (less than 3 %) provided a more stable antenna characteristic, and can therefore preferably be applied as antenna substrate.

Wearable Antennas for Off-Body Radio Links at VHF and UHF Bands: Challenges, the state of the art, and future trends below 1 GHz

“…This process will alter the antenna characteristics. In 2010, it was established that, to ensure stable antenna performance in different environmental conditions, hydrophobic fabrics should be preferred, with a low moisture regain [16] (MR<3, as a rule of thumb).…”

“…The wideband material properties found by non-resonant methods may be used as initial values in a second more accurate resonancebased procedure, where narrowband patch antennas are constructed that resonate close to the frequency band of interest [17], [22]. These structures also enable to accurately quantify the effects of relative humidity or moisture [16], [19], [26], [35], of compression or strain [29], and of repeated washing cycles on the material properties [32]- [34], [36].…”

High-Gain Textile Antenna Array System for Off-Body Communication

“…On the other hand, for the antenna on cotton, the resonance frequency decreases with increasing rH, and the ISM band is no longer covered when the rH is 90%. This is related to the MR value of the two nonconductive substrates: in fact, when choosing a textile material as a substrate for a textile antenna suitable for integration into garment, the MR value of the textile must be taken into account, as indicated in [20]. When varying the rH, the antenna efficiency of the array fabricated on Azzurri substrate remains nearly constant, whereas for the antenna elements of the array produced on the cotton substrate, the radiation efficiency decreases with increasing rH [21].…”

A Dual-Band Low-Profile Metasurface-Enabled Wearable Antenna for Wlan Devices

“…The research of wearable computing systems has experienced rapid development over the past decade due to their great potential applications such as health monitoring, wireless communication and other intelligent terminals [1][2][3]. As one of the key components in the communication system, wearable antennas have received much attention in both academia and industry since their unconventional operating environment is in extremely close proximity to the human body [4].…”