Textile Bandwidth-Enhanced Half-Mode Substrate-Integrated Cavity Antenna With V-Slot for WLAN Communications

Abstract

In this letter, a textile bandwidth-enhanced half-mode substrate-integrated cavity (HMSIC) antenna is designed for the wireless local area network (WLAN) communications. Through simulations over the vector surface current on the top layer of a basic HMSIC antenna, a simple strategy of adding a slot on the top layer to shift the resonance frequency of the rotated TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ {_{2,2,0}^{\rm {HM}}}$</tex-math></inline-formula> mode towards the counterpart of the fundamental TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${_{1,1,0}^{\rm {HM}}}$</tex-math></inline-formula> mode is presented. Based on this, the parameters of the slot are optimized to merge the two corresponding bands into one with an enhanced bandwidth. A prototype with a 0.35 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ {\times }$</tex-math></inline-formula> 0.7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ {\lambda _{\varepsilon }^{2}}$</tex-math></inline-formula> cavity is fabricated and measured to verify the design. The measured −10 dB impedance band is 5.04–5.90 GHz with a 15.7% factional bandwidth covering the 5 GHz WLAN band, and the radiation efficiency is above 94% in free space and 80% on the human body. Besides, the proposed antenna shows high robustness against the human body and cylindrical bending conditions, and the simulated specific absorption rate proves its safety on the human body.