On a foreshortened center-fed whip antenna

Abstract

An experimental investigation was conducted to determine whether the degradation in electrical performance commonly observed with reduced-height helical-wound vertical dipoles can be avoided. A new design approach has been explored which helped define a major cause of this degradation. Data obtained during this investigation supports a working hypothesis that losses associated with circulating currents in the capacitance between turns of a helically wound, electrically short vertical dipole greatly reduce antenna bandwidth and efficiency. The final foreshortened model explored during this investigation met the design objectives for efficiency and interchangeability with the 10 foot whip of the reference antenna. Although other investigators have explored various characteristics of short helical radiators, the design principles evolved during this investigation appear to be new and have produced interesting and unexpectedly favorable results.