New Carolina Windom
The New Carolina Windom antenna is a classical antenna in our series of HS4 Legendary Multiband Wire Antennas. It covers 6 bands, 10-12-15-17-20-40m. Unlike typical antennas, this is a non-resonant, Off Center Fed Dipole (OCFD) antenna. The performance characteristics are quite outstanding. The antenna consists of asymmetrical horizontal radiating elements being driven at the off-center feedpoint through a Balun into a 50 Ohm coaxial cable of a pre-determined length. The principle of a New Carolina Windom antenna utilizes the unique length of the coax section to not only produce the required impedance transformation for taming the SWR to workable limits but also uses the Common-Mode current flowing on the outside of the braid to acts as a part of the antenna radiating structure which results in both horizontal and vertical polarization of the radiated energy. To restrict the Common-Mode current to a desired length, a ferrite core common-mode choke is used at the bottom of this coax section.
This antenna does not essentially need an antenna tuner for proper operation however a 4:1 broadband Balun is required at the element feedpoint to transform the 200 Ohm feedpoint impedance to 50 Ohm coax cable section.. The overall gain on all bands is good with adequate low angle radiation for great DX. This antenna is deployed at a height of 12m (40 ft.) above average quality ground and the design accounts for ground absorption losses, antenna wire insulation dielectric losses, other structural losses, etc.
The most important feature of this antenna is that it produces nearly omnidirectional azimuth pattern with rather good gain and moderate gain ripple on most bands which is practical for copying and working DX in all directions. However, the owner of this antenna will still need to find the optimum direction of the radiation lobe on each band to leverage the main lobe which provides maximum gain. This may be on either side of the default beam heading. It may either be achieved by experimentation during the process of familiarizing the antenna characteristics or by referring to the exhaustive set of specifications with graphics and gain map given below... Happy DXing!