Carolina Windom antenna revisited!

M0UKD gives detailed instructions for construction of the Carolina Windom antenna including the needed line isolator and 4:1 balun. Unlike the usual designs for these, he is using half inch ferrite rod as the core which seemed quite easy to make. For the 4:1 balun he uses 17 bifilar turns on a half inch ferrite rod. The line isolator is made of 10 turns of RG8 on a half inch ferrite rod. This could be made with coax connectors at both ends inside a PVC pipe or simply by winding the feeder RG8 coax around the bare ferrite rod.

M0UKD mentions that his antenna also works even on bands below 40m, on 60m and 80m, though the coax losses will be higher. He has used it even on 160m but found it very inefficient on that band. Ideal mounting height is at least 35 feet above the ground, which improves the radiation pattern. Antenna at his home performs well even at 25 feet elevation above the ground. He used the ratio of 37.8% for one side and 62.2% for the other side after determining the half wavelength at the lowest operating frequency of 40m. That is the point giving 200 ohms impedance, the reason for using 4:1 balun for matching with 50 ohms coax and radio. You can see a lot of nice pictures at the M0UKD website, which has a lot other useful information for amateur radio operators.