Electromagnetic field of the ground-based source surrounded...

7. Radiation Resistance and Input Impedance

[46] The expression for the power P^rad and resistance R^rad of radiation of the source with the given current at the antenna clamps

leads according to (14) and (12) to the following expression for the resistance of this source with a plasma coating

where R₀^rad = 20(kl)² is the resistance of the radiation of the source without a coating. This expression shows that the resistance or power of the radiation at the resonance at the same conducted current increases according to (20) by 2-4 orders of magnitude if the function of influence increases by 1-2 orders of magnitude.

[47] The estimate of the input impedance Z of the emitter on the basis of the results of equations (6) solution relative to the reflection coefficient R_n¹ shows that the ratio Z_Im/Z_Re not at the resonance is high O(1/Ga³). At the resonance frequency, this ratio having the value O(n_p) decreases by almost 4 orders of magnitude if G approx n_p approx 0.01.

[48] The estimate of the power P^rad and conductivity Y^rad of the radiation of a spheroidal slot antenna surrounded by a two-layer plasma coating

taking into account expressions (14) for the tangential components of the field in the wave zone of the source, shows that the radiation power

contains the function of influence squared. At the resonant frequency at fixed voltage at the antenna gap, each component of the field according to (13) increases by 1-2 orders of magnitude (and in some cases by 3 orders). The power or conductivity of the radiation increases by 2-4 orders of magnitude (or more), being maximal for some shape of the spheroid and relative thickness of the plasma layers.

[49] The value of the complex entrance conductivity estimated on the basis of the H_j component of the field at the antenna gap under very thin first plasma layer ( F approx 0 or a₀³ approx 1 ) shows that for the low-frequency branch the ratio is small by the magnitude at the first layer thickness providing the presence of a considerable resonance. The ratio for the high-frequency branch is also small at not too thick second plasma layer.