Wave Propagation Between Buried Antennas

Abstract

Buried antennas can be used in a variety of applications. For surface communication, parameters such as the ground conductivity and the depth of the buried antenna affect the channel attenuation between the antennas. A buried conical antenna for surface communication was developed at Soreq NRC. The antenna is axis-symmetric with two metallic plates, where the upper plate is conical and the lower is a flat disc. The wave propagation from the buried antenna is studied using an axis-symmetric finite-difference time-domain approach. It was found that the energy is radiated from the buried antenna to above the ground, where it forms a spherical surface wave. Due to the wave propagating above the ground faster than below the ground, the penetration of the surface wave into the ground is shaped as a shock wakefield. This wakefield is absorbed into the ground due to the finite ground conductivity. The shock wavefront corresponds to the Cherenkov angle , where is the ground relative dielectric permittivity. The channel attenuation from the buried antenna to a receiving antenna located either above or below the ground surface scales as . Experimental demonstration was performed at 900 MHz. A good correlation was obtained for the channel attenuation between the experimental and simulation results, irrespective of whether the receiving antenna was located above or below the ground surface.Index Terms-Buried antennas, communication channels, finitedifference time-domain (FDTD) methods, shock waves.

Time-Domain Electromagnetic-Field Transmission Between Small-Loop Antennas on a Half-Space With Conductive and Dielectric Properties

“…His solution based on a time Fourier-integral representation consists of two very weak forerunners followed by a dominant wave packet traveling with the so-called group velocity. While the first forerunner observed in the dispersive medium propagates at the speed of light much like the initial disturbance described by (30), the latter is not subject to drastic exponential damping.…”

“…In the second case, the lower half-space is described by 1 = 4.0 0 , again, and by a non-vanishing electric conductivity σ = 50 mS/m (see [30,Sec. III.B]).…”

Link Budget Maximization for a Mobile-Band Subsurface Wireless Sensor in Challenging Water Utility Environments

“…A comparison between the proposed antenna and previously published works, in terms of size, operating frequency, bandwidth, minimum return loss, peak gain, polarization, and radiation pattern, is listed in Table I. As can be seen, most of the previously reported structures [11], [12], [19]- [23], [25], [26], [28], [30] are designed for narrow bandwidth single band, except that [29] is proposed for dual narrow band operation and [24], [27] are intended for wideband operation. It is noticeable that only [24] is able to cover the required GSM bands but the size is much larger than the design proposed here.…”

“…For this reason, many antenna design concepts [14]- [25] have been proposed and implemented for underground applications. For STS underground communication, a zig-zag shaped monopole designed for 915-MHz operation [11] and an inverse triangular monopole antenna intended to operate from 900 to 1500 MHz [19] have been explored. For STB underground to above-ground communication, it is noticeable that many antenna design innovations have been developed to establish reliable and longer distance wireless links to above-ground mobile network base stations [20]- [30].…”

“…Among all the above designs [19]- [29], it was found that they are mostly only capable of offering narrow single band operation [19]- [23], [25], [26], [28], [29]; only very few such as in [24] and [27] can handle wideband operation, with the compromises that that entails, and no design is optimized for dual-band operation. There is also the pragmatic constraint that utility companies do not wish to replace their existing manhole covers, which are predominantly made of cast iron.…”