Abstract
The gain of some aperture antennas can be significantly increased by making the antenna near-field phase distribution more uniform, using a phase-transformation structure. A novel dielectric-free phase transforming structure (DF-PTS) is presented in this paper for this purpose, and its ability to correct the aperture phase distribution of a resonant cavity antenna (RCA) over a much wider bandwidth is demonstrated. As opposed to printed multilayered metasurfaces, all the cells in crucial locations of the DF-PTS have a phase response that tracks the phase error of the RCA over a large bandwidth, and in addition have wideband transmission characteristics, resulting in a wideband antenna system. The new DF-PTS, made of three thin metal sheets each containing modified-eight-arm-asterisk-shaped slots, is significantly stronger than the previous DF-PTS, which requires thin and long metal interconnects between metal patches. The third advantage of the new DF-PTS is, all phase transformation cells in it are highly transparent, each with a transmission magnitude greater than − 1 dB at the design frequency, ensuring excellent phase correction with minimal effect on aperture amplitude distribution. With the DF-PTS, RCA gain increases to 20.1 dBi, which is significantly greater than its 10.7 dBi gain without the DF-PTS. The measured 10-dB return loss bandwidth and the 3-dB gain bandwidth of the RCA with DF-PTS are 46% and 12%, respectively.
Highlights
The gain of some aperture antennas can be significantly increased by making the antenna near-field phase distribution more uniform, using a phase-transformation structure
This paper addresses the challenge of mechanical stability and presents a novel dielectric-free phase transforming structure (DF-PTS)
We propose a novel dielectric-free phase-shifting cells (DF-phase-shifting cell (PSC)) configuration that is slot-based as opposed to the patch-based approach in[38]
Summary
The gain of some aperture antennas can be significantly increased by making the antenna near-field phase distribution more uniform, using a phase-transformation structure. This design draws its inspiration from the multilayered dielectric based printed metasurfaces, but with a notable difference that instead of dielectric laminates, the array of conducting patches are mechanically supported by a grid of thin metallic strips The width of these metal strips in the grid is only 0.4 mm, which made metasurface fabrication complicated and significantly compromised the mechanical strength and stability of the metasurface when hundreds of conducting patches are required for a typical metasurface, for example, to correct near-field phase distribution of a high-gain antenna
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