Topband: Elevated Radial Lengths

[Dennis W0JX]

On 80 meters, my vertical uses four elevated radials, each are 48 feet in length and about 11 feet high. They are tied together at the center and loaded with a small Air Dux coil of approximately 3.4 uh. The other end of the coil is tied to the coax shield. This antenna works better than the antenna did when it had full sized radials. A bonus is that the antenna can be resonated to a desired frequency by simply changing the tap on the coil. The wire radiator is cut for a 1/4 around 3650.

To achieve 1:1 SWR, I have a shunt matching coil across the vertical wire and coax shield.

I believe that Dave, W5UN used 96 foot long radials on his 160M 4 square and a similar coil loading setup. The above shortened radial designs follow recommendations made by Dick Weber, K5IU, who empirically demonstrated that 1/4 wave radials are inferior to properly shortened sixty degree (or lengthened 120 degree radials),

73, Dennis W0JX