Experimental and numerical studies on the receiving gain enhancement modulated by a sub-wavelength plasma layer

A novel technique based on sub-wavelength plasma structure effects on enhancement of RF communication signals on a receiving antenna is carried out in this paper in laboratory experiments and analyzed by corresponding numerical simulations. Considerable intensification on receiving signal gain up to ～10 dB in comparison with that without the plasma modulation is observed experimentally in ～1GHz RF band, with an effective enhancement bandwidth of ～340 MHz and the fractional bandwidth of ～34%. Then, the optimal modulation parameters of plasma are further studied by a numerical simulation. It is shown that the number density, the layer thickness, and the collision frequency of the plasma, as well as the relative distance between the plasma layer and antenna synergistically affect the modulation. Compared to the metallic antenna with the same overall dimension, the modulated antenna covered by the sub- wavelength plasma structure features higher receiving efficiency and lower radar cross section in the studied RF band. The mechanism of the reception enhancement is further revealed by analyzing characteristics of electromagnetic scattering and electric field distribution in the sub- wavelength plasma layer. The results then exhibit scientific significance and application potential of sub-wavelength plasma modulation on compact receiving antennas with higher performance and better feature of radar stealth.