[TZ] Elevated radials vs buried ones

Tue May 17 22:43:22 CDT 2016

Elevated radials are almost ten times more efficient that buried radials. The trick is getting the radiation angle right. Many papers written on the subject. There is a station in SF bay just before the airport in the water with elevated radials. 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch - K9ZC
Staunton, Illinois

Owner - Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com

email:  bill at wjschmidt.com

On May 17, 2016, at 9:32 PM, Mike McCarthy <towers at mre.com> wrote:

>Rolf,

>I would think some modeling might be in order. There has been some
>research done on this and I seem to recall 8 wires 8-10 deg. above the
>ground gets you to within a couple dB of the buried system. They need to
>take off at 45 deg. angle from the base of the tower to the horizontal
>runs.  Which by my calculations would be between 7 and 9M AGL. and some
>90M in length.

>But don't take my word for that as fact. You need to do the leg work or
>have a person exceedingly familiar with NEC run the model for you.

>Let me also suggest that if coverage is reduced, perform field
>measurements and go to the governmental agency regulating AM's and ask for
>a power increase to compensate for the loss of efficiency.

>As for cutting the tree tops, that would essentially kill the trees as the
>vast majority of the growth occurs at the top.  If it is possible, seek a
>limited permit to clear a narrow (say 6M) path along each radial's bearing
>to protect against damage to the radials from high winds blowing trees
>into the radials.  Then make sure the paths are cut at least annually.

>MM

>On Tue, May 17, 2016 6:50 pm, Rolf Sandmeier wrote:
>>Dear Braintrust

>>An AM station, 40 kW, 910 kHZ, single tower 330 feet had half the radial
>>wires stolen.

>>To worsen the situation, vegetation including 10 to 30 ft slim trees have

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