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Radar cross section simulation of metal cone covered with plasma

Plasma is known to absorb electromagnetic waves with frequencies below characteristic plasma frequency ωp, and attenuate those with higher frequencies. The absorption capability is proportional to the square root of plasma density, and its effect can be measured in term of its radar cross section (RCS). Such phenomena appear naturally on reentry vehicle which causes radio blackout. Recently investigations on intentionally generated atmospheric or low pressure plasma in front of projectile to reduce its RCS and achieve low probability of interception (LPI) are of interests. We simulate the RCS of a near 20 degree metal cone, and compared it with the one covered by a ball shape plasma in front of it. The results indicated the RCS dependence with frequency is changed, and the RCS decreases at the bore sight direction when the incoming radar signal is below ωp, but may become higher when frequency is higher than ωp. The shape of the plasma is as important as the density in absorption capability. The results imply plasma cloaking is theoretically effective.