On the Theory of Radiation From a Raised Electric Dipole Over an Inhomogeneous Ground Plane

Abstract

The influence of a finite ground plane on the field of a raised electric dipole is considered from an analytical standpoint. The method for evaluating the integrals is discussed briefly and some asymptotic results are given which illustrate the limiting behavior for ground screens of large diameter. It is shown that the resulting pattern may be crudely interpreted in terms of the direct radiation of the source dipole, its image in an infinite ground plane, and contributions from the edges of the ground screen.

Performance of Ground-Based High-Frequency Receiving Arrays with Electrically-Small Ground Planes

“…Wait et al published results for small radial-wire ground planes [3]; large radial-wire ground planes [13,17]; small disk ground planes [3]; large disk ground planes [6,17]; large ground screens [4,9,12,14]; nonhomogeneous Earth [5,7,8,10,11,15]; and assorted ground planes [16]. Rafuse and Ruze [18] published results for large ground screens and radially-nonhomogeneous Earth.…”

“…The receiving system available loss factors/c, gin, and In of the antenna, matching network, and transmission line, respectively, are given by references 28 and 39 as: Equations (3-9) and (3)(4)(5)(6)(7)(8)(9)(10) are generally functions of the antenna input impedance Zin.…”

“…The input resistance decreases aperiodically to an asymptotic value of 36 ohms as the disk radius increases (see figure 3-7). The input reactance increases aperiodically to an asymptotic value of 22 ohms for a very thin [3][4][5][6][7][8][9][10][11][12][13][14][15][16] monopole element (see figure 3-8). The input reactance is a stronger function of the element radius than the radiation resistance [40].…”

“…The external noise factor fa in equations ( F fao, uniform angular distribution fa = fao dr (00, 00), point source angular distribution for a source at 0= 0 0, 0=0o (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) for a source at 0 = 00, =0…”

“…_ 8.0 wavenumbers and possibly larger radii. Accordingly, d CCIR (a) is better approximated by equation (2)(3) than by equation (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17); namely, Similarly, the peak intensity of the angular distribution of external noise is not significantly affected by the extent of the ground plane for a given external noise factor and shape of the angular distribution, provided that the external noise is angularly-distributed over a large solid angle. For example, the peak intensity of the angular distribution for electrically-small ground planes relative to that for a perfect ground plane will be unchanged for uniform external noise; increased by a factor of (2.6/1.805) = 1.44 = 1.6 dB for external noise with a peak at 30 degrees above the horizon (see table 3-2).…”