Design of dual frequency antenna with gain enhancement effect for microwave power transmission

This paper proposes a method for enhancing antenna gain based on a zero-refractive-index metasurface, which can improve the gain of antennas under bending conditions and mitigate the gain reduction caused by deformation in flexible antennas. The metasurface enhances gain by suppressing magnetic field changes caused by bending. The key novelty is to leverage the dual-band near-zero refractive index behavior to actively regulate the wave vector so that electromagnetic waves passing through the metasurface tend to be redirected toward the surface normal even under conformal bending or oblique incidence. A flexible dual-band antenna was designed to verify the effect of the metasurface on improving antenna gain. The proposed antenna operates in the frequency ranges of 2.43–2.47 and 5.72–5.9 GHz. The effect of the metasurface is analyzed through the fabrication and measurement of the antenna. This study reveals that when the antenna is flat, its gain at 2.45 and 5.75 GHz is 7.53 and 9.32 dBi, respectively. In bending conditions, the metasurface significantly enhances the antenna’s gain, with greater bending leading to more pronounced improvements. The maximum increase in the gain reaches 1.69 and 2.74 dBi, respectively. When the bending radius is reduced to 40 mm, the received power increases from 68 and 13.7 to 89.7 and 21.3 mW, respectively. The received power of the antenna increases by 31% and 55%, respectively, under bending conditions. The experimental results indicate that, after bending, the antenna with the metasurface can receive more power, consistent with the improved gain results.