Microwave Linear Displacement Sensors Integrated With Filtering Antenna for Simultaneous Sensing and Wireless Communication

In this article, a novel microwave linear displacement sensor integrated filtering antenna (SIFA) is proposed, which can be used for linear displacement sensing and wireless communication simultaneously. The proposed SIFA system is designed based on a coshared resonance element, a monopole antenna, a single-mode ring resonator, and a phase alignment element. By cleverly using the even/odd resonance modes in the coshared resonance element it can simultaneously provide two independent passbands for linear displacement sensing and wireless communication. It is worth noting that the coshared resonance element is also beneficial to constructing the filtering antenna (FA) with the monopole antenna and providing one more sensing parameter for the linear displacement sensor. The proposed SIFA system consists of two substrate layers. With the displacement of the slider in the top layer, three sensing parameters (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\angle S_{22}$ </tex-math></inline-formula>, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\angle S_{21}$ </tex-math></inline-formula>, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{tz}$ </tex-math></inline-formula>) can obtain a relatively linear variation while not affecting the wireless communication function. A comprehensive analysis is carried out to guide the proposed SIFA system design. In order to verify the proposed design method, a demonstrated prototype integrated with linear displacement sensors and FA for 2.4 GHz Wi-Fi communication is simulated, implemented, and measured. Satisfying results are obtained in the simulated and measured results, showing the feasibility of the proposed codesign method for the SIFA system.