A new concept in high frequency antenna design

The application of unidirectional, wire, trapezoidal-tooth, log periodic antennas to h-f point-to-point communications is described. The antennas are placed over ground in such a manner that the vertical plane radiation pattern, as well as the azimuth pattern and input impedance, is essentially independent of frequency over the 3-to 30-mc range. Moreover, the design parameters can be chosen so that the upper half-power point will fall at any vertical angle from 70° down to a few degrees. The antennas are horizontally polarized with azimuthal beam widths of 60°, low side lobes and gains ranging from 11 db to 18 db over an isotrope. Optimum elevation plane patterns for point-to-point paths as a function of extreme ionospheric virtual heights are defined, and antenna designs producing these patterns are given.