Parameters of a Short Dipole Antenna Placed Over a Two-Layer Lunar Soil

Abstract

In this paper, the performance characteristics of a horizontal symmetrical dipole antenna, located in the immediate vicinity of the Moon’s surface, are numerically analyzed. The lunar soil is assumed as a flat-layered medium composed of two lossy dielectrics, the upper layer with a thickness of 5–10[Formula: see text]m, filled with regolith, and solid bedrock in the form of granite or basalt. Calculations were performed in the frequency range of 1–100[Formula: see text]MHz, which is interesting for low-frequency (LF) and very low-frequency (VLF) radio astronomy. The frequency dependences of the impedance, the radiation efficiency, and the effective area of a thin wire dipole with a short length are investigated. All calculations were carried out by simulation of the dipole using the well-known Altair Feko software. As a result of the calculations, it was found that the frequency characteristics of the dipole parameters above the two-layer medium have characteristic differences from the same for the dipole above a homogeneous medium, namely, they have oscillating components, the period and magnitude of which depend on the parameters of these media and the thickness of the upper layer. The presence of this oscillating component is largely manifested in the dipole efficiency and effective area but to a lesser in its impedance. The dependence of the dipole radiation pattern (RP) on the frequency also is analyzed in detail, making it possible to detect the quasi-periodic changes in its shape, which are clearly synchronized with the oscillating component of the dipole radiation efficiency.