I am very interested in the shortened radials hypothesis. Has there been any
documented testing of full length vs shortened radials done ?
Bob
K6UJ
> On Aug 29, 2020, at 7:16 PM, Richard (Rick) Karlquist <richard@karlquist.com>
> wrote:
>
>
>
> On 8/29/2020 5:44 PM, Dennis W0JX via TowerTalk wrote:
>> 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
>
> I'm not following the logic here. If various radials have
> unequal impedances, I don't see now tying them in parallel
> though a coil or capacitor with magically make them have
> equal currents. Did Dick actually compare the currents in
> the various configurations as built? All I see are anecdotes,
> not AB comparisons or measurements.
>
> Now if someone told me to use shortened or lengthened radials
> and put individual coils or capacitors in series with each radial, then
> I might believe the currents would be forced into equality.
> Are you sure you got the story straight about Dick's article?
> (I don't have access to it).
>
> 73
> Rick N6RK
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