Radiation resistance of an oscillating dipole in a moving compressible plasma

The radiation resistance of an electric dipole located in a moving compressible plasma is treated. First, the wave equations for a uniformly moving compressible plasma in the presence of a current source without any restriction upon the magnitude of the velocity are derived. Then, using these wave equations the radiation resistance of the present problem is obtained and its characteristics are investigated numerically. It is shown that if the moving velocity of plasma exceeds the thermal velocity of the electron , a region appears in which the plasma wave component of the radiation resistance becomes negative. In this case, the numerical calculation shows that there is a range of where the radiation efficiency of the electromagnetic wave is much improved. The cutoff frequency of the plasma wave in a moving compressible plasma becomes lower than that of the plasma wave in the rest frame of the plasma.