Efficiency-Driven Design for Planar Antennas With Lossy Materials

Abstract

This article demonstrates a design strategy for improving the radiation efficiency of a planar antenna made of a layered conductor of MXene with modest conductivity on a lossy PDMS substrate. New methods to reduce the conductor loss and the dielectric loss are proposed. On the one hand, the conductor loss is minimized by identifying the location of high current density on the antenna radiator, and then accordingly altering its shape to redistribute the surface currents as uniformly as possible. On the other hand, the dielectric loss is reduced by employing a folded ground plane with elevated edges. This ground plane structure reduces the concentration of the electric field in the dielectric substrate and thus minimizes the power dissipation due to dielectric loss. The improvement techniques are implemented starting from a standard U-slot microstrip antenna. The method demonstrates to improve the radiation efficiency significantly by an average of 14% for a microstrip antenna fabricated using MXene conductor with a sheet resistance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 {\Omega }$ </tex-math></inline-formula> /square and a lossy PDMS substrate. Importantly, the proposed method can preserve the overall antenna size and the operating frequency band. The optimized antenna exhibits a high radiation efficiency of 71% and offers a wide impedance bandwidth of 56% covering operation for the 5 GHz WLAN band.