An Epsilon-Near-Zero-Inspired PDMS Substrate Antenna With Deformation-Insensitive Operating Frequency

Abstract

In this letter, we transplant the epsilon-near-zero response into the design of a flexible antenna with invariant operating frequency using the magnetron sputtering and through-silicon-via crafts. The antenna is based on a section of substrate-integrated waveguide operating at its transverse TM<;span style="font-size: 14.5px;"> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</sub> <;/span>and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> modes, to provide a difference pattern and a sum broadside pattern, respectively. The flexibility of the polydimethylsiloxane (PDMS) substrate enables the radiation pattern to be adjusted by arbitrarily bending the antenna without changing its operating frequency. The prototype operating at the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</sub> mode around 6.58 GHz is fabricated and tested. Measured results are in agreement with the simulation, demonstrating stabilized operating frequency and radiation pattern adjustability in terms of gain, beamwidth, and mainlobe orientation. Our design may survive harsh deformation and lead to rich applications in flexible wireless electronics, such as biosensing and smart bracelet.