[TowerTalk] Unequal Radial Currents

[Dennis W0JX]

Unequal currents in 1/4 wave radials is to be expected primarily due to three factors: 1.) varying quality of the ground under each radial; 2.) the effect of close by objects such as buildings and other towers; and 3.) the variation in the length of the radial wires depending on type of wire, insulation, and construction methods. Effect on the actual radiation pattern depends, of course, on the severity of the current variation and the number of radials utilized.
Dick Weber, K5IU, wrote a very informative article in the late 90's which was published in Communications Quarterly. He argued that 1/4 wave long radials were the poorest length on could use. He strongly recommended radial lengths of either 60-70 degrees (shortened) or 120 degrees long. These radials are tied together at a common point and fed either through a coil or a capacitor.
W5UN had a very successful 4 square for 160 meters which used four, 96 foot long radials fed through a common coil. The radials were about 15 feet off the ground.
Here at W0JX, I have four, 48 foot radials on my elevated 80 meter ground plane. The four radials come to a common point below the radiator and are tied to the coax shield through an inductor of approximately 3.3 uh. A big advantage of this arrangement is that I can resonate the antenna system by moving the tap on the radial loading coil. After many years of using full-sized radials, my on the air results tell me that the shortened radials are working better than the full size radials did.
73 Dennis W0JXMilan OH