Electromagnetically coupled microstrip textile patch antenna design model and construction process for smart clothing applications

Resumen

Textile EMCMPA (Electromagnetically Coupled Microstrip Patch Antenna)s currently face significant challenges to be considered for off-body BCWC (Body Centric Wireless Communications) applications. Research has shown that EMCMPAs are suitable for off-body communications, as they avoid the use of rigid components or galvanic soldering; they achieve high gain and radiation efficiency values in desired directions; and its ground plane reduces the negative effect of human body proximity. Nevertheless, they have two main challenges: the lack of a specific design model and their high fabrication complexity. This study aims to determine an EMCMPA design model to easily obtain its initial dimensions, and a textile fabrication process to reliably assemble them. Building on the existing work about textile EMCMPAs for off-body communications, it asks: to what extend modeling EMCMPAs with TL (Transmission Line) models can provide accurate and efficient textile antennas? In this context, TLs are simple analytical models that provide good and intuitive understanding of the initial dimensions and EM (Electromagnetic) performance of the antennas, combined with a reasonably accurate mathematical formulation. Based on the literature, these models can predict the initial dimensions of one part of EMCMPAs, but they do not provide all antenna dimensions. In addition, few designed and measured textile EMCMPAs have been reported, with no validated fabrication techniques, nor efficient antenna results. Analysis of the results demonstrated that using the proposed combination of TL, efficient textile EMCMPAs for the 2.45 GHz ISM (Industrial, Scientific and Medical) band were obtained, presenting initial values for all dimensions of the antennas, with measured resonance frequency errors below 6%, and excellent free-space and on-body measured BW (Impedance Bandwidth), maximal gains, and high radiation efficiencies. It also demonstrated that using an alignment method, based on laser-cut wood, with a fast intralayer attachment method, and thermally activated adhesive sheets to fabricate textile EMCMPAs, exhibited standard deviation results of measured resonant frequencies, BW, maximal gains, and total radiation efficiencies equal to 24.54 MHz, 14.02 MHz, 0.15 dBi, and 3.57%, respectively. The results indicate that the obtainment of efficient textile EMCMPA prototypes, by using a novel antenna design model and a reliable fabrication process, makes them a serious candidate for future smart clothing applications.