Roger,
5/8 wave radiators are *not* popular with AM broadcast stations. In fact,
the 185-195 degree class of radiators used by WSM, WLW, and many other clear
channels was so chosen to specifically eliminate the high-angle lobe created
with 5/8-wave radiator height. The skywave created by the high lobe cancels
with ground wave and the result is disastrous. Find me just one AM clear
channel with a 5/8 wave radiator :-))
Paul, W9AC
----- Original Message -----
From: "K8RI" <K8RI-on-TowerTalk@tm.net>
To: <towertalk@contesting.com>
Sent: Tuesday, November 29, 2011 3:25 PM
Subject: Re: [TowerTalk] 10M phased verticals
> On 11/29/2011 1:45 PM, Paul Christensen wrote:
>> I just modeled a 10m four-square in 4Nec2. I used 60 #14 AWG radials
>> 5/8-wave long over average soil, and 5/8 wave radiators. The F/B is
>> terrible at 1/4-wave spacing. At best, it's about 12dB at an elevation
>> of
>> 45 degrees. As would be expected with a 5/8wave vertical, two lobes are
>> present. Maximum FS with this ground occurs at 15 degrees elevation with
>> a
>> secondary lobe at about 60 degrees elevation. The second lobe is within
>> 3dB
>> of the primary lobe. Reducing radial length to either 1/4 or 1/2 wave
>> has
>> minimal effect on pattern. There may be other combinations of spacing
>> and
>> source phase with 5/8 wave verticals that yield better pattern results.
>>
>> I'm not sure why anyone would want to use 5/8-wave verticals on HF. We
>> tend to equate 5/8-wave with maximum 0-degree elevation gain (usually
>> from
>> VHF/UHF antenna literature). If someone has a compelling reason to use
>> 5/8-wave *vertical* radiators on HF, I would like to hear about it.
>
> They are popular for clear channel broadcast stations and 160 meter DX.
> No the angle over even a good
> radial system is not 0 degrees, but it is low.
>
> 73
>
> Roger (K8RI)
>
>
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