Pattern of a Linear Antenna Erected Over a Tapered Ground Screen

Abstract

FIG. 1. A linear antenna erected over a sector ground system whose surface impedance differs from the surrounding ground plane.IThis work was carried out while the author was a visiting professor a

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).…”