Abstract
Solving or mitigating the blackout problem suffered by hypersonic vehicles as they re-enter the atmosphere is essential for the smooth communication of hypersonic vehicles. An antenna–sheath–plasma layer configuration is proposed, whose analytical results indicate that the attenuation of the wave mode can be reduced significantly through optimizing the sheath thickness between the hypersonic vehicle antenna and the surrounding plasma layer. Detailed investigations show that because the wave frequency is greater than the plasma frequency, i.e., ωpe < ω, there exists great influence of the sheath thickness parameter δ on the propagation constant for the m = 1, 2, 3 modes as δ ∈ (0.01, 1) and for the m = 0 mode as δ > 1; for the ωpe > ω case, δ imposes a significant effect on the propagation constant for the m = 0, 2, 3 modes as δ ∈ (0.1, 2) and for the m = 1 mode as δ < 1; in addition, it shows that the attenuation constant for the m = 1 mode is always non-zero, which implies that the blackout problem is mainly caused by the m = 1 mode when ωpe > ω.
Highlights
INTRODUCTIONScitation.org/journal/adv plasma frequency is increased beyond the antenna frequency, and later, by employing a lossy plasma layer, they detailed the influences of antenna frequency on radiation intensity for three different values of sheath thickness. Most recently, by adding a matched layer between a cylindrical antenna surface and the surrounding plasma layer, Gao presented a perfect radiated performance of the antenna by optimizing the relative permittivity of the matched layer
From the early 1960s, the essential role of the sheath region in the radiation enhanced phenomenon (REP) of an antenna–sheath– plasma layer (ASPL) configuration has been deeply recognized and experimentally observed
In 1965, by employing a variational technique in an ASPL configuration, Pinder numerically obtained the dispersion curve for the lowest order circularly symmetric slow wave propagating in the system and found that the curves of the propagation constant for a non-uniform plasma case are lower than those for a uniform plasma case
Summary
Scitation.org/journal/adv plasma frequency is increased beyond the antenna frequency, and later, by employing a lossy plasma layer, they detailed the influences of antenna frequency on radiation intensity for three different values of sheath thickness. Most recently, by adding a matched layer between a cylindrical antenna surface and the surrounding plasma layer, Gao presented a perfect radiated performance of the antenna by optimizing the relative permittivity of the matched layer.. Scitation.org/journal/adv plasma frequency is increased beyond the antenna frequency, and later, by employing a lossy plasma layer, they detailed the influences of antenna frequency on radiation intensity for three different values of sheath thickness.. By adding a matched layer between a cylindrical antenna surface and the surrounding plasma layer, Gao presented a perfect radiated performance of the antenna by optimizing the relative permittivity of the matched layer.. As we may have noticed, in previous investigations, only the radiation intensity for several different values of sheath thickness in a spherical antenna for a lossy plasma layer case was studied; the effect of sheath thickness on the propagation constant for both the azimuthally symmetric and asymmetric modes have not been analyzed so far, nor have been the comparison of the propagation characteristics between them.
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