FDTD simulations on radar cross sections of metal cone and plasma covered metal cone

Abstract

Electromagnetic wave interaction with a plasma covered metal surface has been studied using the Radar Cross Section (RCS) changes of a 10 cm diameter and 30 cm height metal cone with and without plasma coverage. A Finite-Difference-Time-Difference (FDTD) method was use to calculate the case of a cone with and without a covering of a 1 cm thick sheet plasma for both S Band (2,3, and 4 GHz) and X Band (8, 10, and 12 GHz) frequencies. The characteristic plasma frequency ωpe was set at 10 GHz, and electron-neutral collision frequency νen chosen to be 20 GHz. The results indicate that the metal cone has very small RCS at head-on direction, and a large RCS looking from the back end. A Plasma covered metal cone was shown to achieve head-on direction monostatic RCS changes between −0.47 and −7.2 dBm2 from 2 to 4 GHz, and −11 to −3.2 dBm2 RCS changes from 8 to 12 GHz, but at the back end the RCS increases between 2.2 and 2.6 dBm2 from 2 to 4 GHz, and varies between −0.9 and 0 dBm2 from 8 to 12 GHz. In the two frequency bands investigated, maximum RCS reduction of −15 dBm2 occurs at 8 GHz at the same direction as the incident electromagnetic wave polarization. Plasma stealth offers advantages like frequency tunability, but the challenge is establishing an adaptive feedback mechanism that can main a constant plasma density and thus a constant RCS by adjusting the power supplied to plasma generator while monitoring the changes in air speed, altitude, and humidity.