HI Tom,
Your knowledge has beed very beneficial to the topband antenna discussions.
However, there are many factors to optimizing a 160m antenna. The first
thing you have to do is decide what you want to optimize it for. Broadcast
engineers have done a lot of study on low frequency verticals. Their mission
is to maximize field strength in their service area usually less than 50
miles. Radiation of sky wave is lost power and can cause interference to
other stations assigned to the same frequency. In my case my goals are just
the opposite. Generating a ground wave causes local interference and reduces
the skywave energy. I'm sure if I were located on level lowland I would want
to put out a thousand 300 foot radials but that isn't possible. One thing
that Jeff said is true under all cases is that a ground screen in the
vicinity of the antenna will reduce near field losses. This is true
regardless of using ground mounted or elevated radials. This loss is not
taken into account in many of the computer modeling programs. This accounts
for some overly generous calculations of total gain for low horizontal
arrays. When the ground is good it can deliver up to 6 db of ground gain but
if it is poor it can suck out 10 or 40 db. Every QTH is a little different.
It all gets back to what works best for you is best for you. Thanks for
allowing bandwidth for this discussion. 73
Darrell, N6DX@aol.com
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