Degradation of on board antenna performances by re-entry plasma during supersonic or hypersonic re-entry of flight vehicles and its mitigation technique by application of d.c magnetic field

Ionization of neutral air molecules and heat shield ablation are the prime sources for generation of non-uniform and non-equilibrium plasma layers around re-entering supersonic or hypersonic missile liked flight vehicles. The ionized plasma layer not only reflects and attenuates the propagating electromagnetic (e.m) wave at certain concentration of electrons but it also degrades the on board antenna performances and produces very poor antenna efficiency, input impedance mismatch and undesired nulls in the desired radiation patterns-which results in RF black out during re-entry. This paper presents the analysis of degradation of on board antenna performances caused by the non-magnetized re-entry plasma and its mitigation technique at transmission frequency below the plasma resonant frequency by the application of suitably strength d.c magnetic field in the direction of on board dipole antenna radiation.