Input impedance, current distributions, and radiation properties of thick and widely spaced folded dipoles

The folded dipole antenna with practical curved edges is analyzed by the mo ment method and results are given for the input impedance covering a wider range of thicknesses and spacings than that previously known. The graphs pr esenting this input impedance as a junction of conductor diameter, spacing between arms, and antenna length are more complete and easier to interpret than those traditionally published in logarithmic form. It is also demonstr ated, with plotted current distributions, that the conventional assumption that the currents in both arms are equal in magnitude is inaccurate, even f or small spacings of the order of 0.05 lambda. Finally, a discussion on the radiation pattern, usually ignored or not mentioned in the available liter ature, is given for this important aerial, comparing it in gain and beamwid th with those of a single center-fed dipole and of a directed dipole antenn a.