Effect of Thin Plasmas on an Aperture Antenna in an Infinite Conducting Plane

Abstract

It is shown that for the plasmas present around a wide variety of reentry vehicles, it is acceptable to replace the plasma by an impedance sheet. Using this notion, a variational expression for the admittance of an arbitrary aperture (fed by a waveguide) in an infinite conducting plane covered by an impedance sheet is developed, and examined in some detail. We found that a purely real impedance sheet tends to suppress the higher‐order modes, while a purely imaginary sheet can enhance or suppress the higher modes, depending upon their nature.

Calculation of the Admittance, Isolation, and Radiation Pattern of Slots on an Infinite Cylinder Covered by an Inhomogeneous Lossy Plasma

“…In addition, the re-entry plasma may decrease (or increase) the isolation between different antennas on the same vehicle. To predict these effects theoretically, various researchers [Galejs, 1965;Fante, 1967a;Golden and Stewart, 1969a] have modeled the plasma-covered re-entry vehicle by a plasmacovered ground plane. This model is useful at frequencies sufficiently high that vehicle curvature is unimportant, but it obviously fails at lower frequencies.…”