On 11/29/2011 3:43 PM, Paul Christensen wrote:
> 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.
Depends on where you want to reach. 5/8 is good for long distance, but
not intermediate.
> Find me just one AM clear
> channel with a 5/8 wave radiator :-))
There was one down in the Caribbean which then was modified to a 5/8 on
160.
73
Roger (K8RI)
> 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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