Numerical Investigation on Interference and Absorption of Electromagnetic Waves in the Plasma-Covered Cavity Using FDTD Method

We present real-time status of the electromagnetic (EM) scattering by the plasma-covered metal cavity, using the 2-D finite-difference time-domain method. The interference and absorption of EM waves of such progresses were analyzed. The variations in their return loss as a function of incident angle, frequency of EM wave, electron density of plasma, and plasma collision frequency were also presented. The results show that when the EM wave hits the cavity at the front aspect angle, the signals propagate along the central axis of the cavity, and the returning waves converge to source for all incident frequencies. On the contrary, when the EM wave hits the cavity at the oblique aspect angle, the combining of reflected waves among the inner walls of the cavity will result in constructive or destructive interference, consequently the returning wave not converging to source any more. The values of peak return loss are extremely different between plasma-covered metal plate and plasma-covered metal cavity. The former is less than 4 dB, while the latter reach to as large as 25 dB. The appropriate parameter regimes of plasma can be chosen for more efficiency design.