Studies On The Plasma-Added Intensification Of Gigahertz Radio Frequency Signals

The technology of antenna miniaturization and electromagnetic radiation enhancement has been a hot topic in recent years. And numerous novel methods and techniques have been proposed and investigated towards the future generation of compact antennas with wide-range requests. The application of plasma, a typical metamaterial with negative permittivity, provided a new approach to improve the efficiency of the antenna radiation on communication [1, 2]. In this paper, to further research the technology based on modulation and enhancement effects of sub-wavelength plasma structures on radio frequency (RF) electromagnetic radiation, the numerical simulation and corresponding experiment have been conducted. Firstly, a numerical model based on multi physics simulation software Comsol Multiphysics was built to reveal the enhancement law and mechanism of sub-wavelength plasma structures on RF electromagnetic radiation by changing the shape of plasma, the density distribution of plasma and the collision frequency of plasma. Correspondingly, an inductively coupled plasma was applied to provide appropriate sub-wavelength plasma structures aiming at enhancing RF electromagnetic radiation of an omnidirectional ellipse dipole antenna. And a significant enhancement of electromagnetic radiation up to $5 \sim 10$ dB higher than the free-space radiation on RF antenna signals of $\sim 1$ GHz or higher has been observed, which exhibited a good agreement with the numerical simulation results, the absolute bandwidth reached 170 MHz and the fractional bandwidth reached 17.6%. The results and their discussions have demonstrated the feasibility of the RF radiation enhancement by subwavelength plasma structures in an applicable range of RF bands, such as L-band, and a promising potential in the field of antenna radiation modulation and enhancement.