Topband: S9SS On 160

[Bill Tippett <btippett@alum.mit.edu>]

W8JI wrote:
>VK3ZL does V vs. H tests comparing a dipole at 110 feet to a ~45 foot
vertical, and any given day either could be stronger. As a general rule, his
dipole has the highest chance of being stronger only at high solar
disturbances or very near his sunset. Most of the time the vertical is
better. As a matter of fact, he almost never finds the H better except when
propagation is disturbed or at a "sun exposure".

>I found the same thing here. At or near my sunrise "peak" my horizontal
antennas all evened out more with verticals. At the same time, the signal is
obviously scattering or multi-pathing because the Beverage and vertical
arrays lose directivity.

        I suspect differences have much more to do with takeoff angles 
(TOA) than
polarization.  I put up an inverted-V on my 100' tower in January to maximize
high angles and Eznec shows ~100' is about the optimum (to maximize gain at a
90 degree TOA).  The breakeven angle for equal gain with my vertical array is
at ~40 degrees TOA.  Although the vertical is better for DX >95% of the time,
there are times when the inverted-V is clearly superior.  Normally these seem
to be near sunrise and sunset, but not always.  Furthermore there is no
consistency from one day to the next even at sunrise/sunset.  I've seen days
when the inverted-V will be VERY superior (>10 dB) to the 3-element vertical
array but the next day it will be the opposite.  The other strange thing I've
noticed is that differences are not always reciprocal for transmit and receive.
For example, last night the inverted-V sounded nearly as strong as the vertical
array on receive, but transmit tests indicated the vertical was stronger in EU
by several S-units.  BTW, XF4IH was a true 599 yesterday at my sunrise on the
inverted-V (vertical array is presently fixed NE so I can't say what he would
have been if oriented SW).  I also worked 9V1GO with the inverted-V after 
sunrise
last week long after Bob had faded out on my NNW Beverage (which is low angle).

        I guess this simply proves the old adage "You can't have too many 
antennas"!

                                                73,  Bill  W4ZV

P.S.  Here is a plot comparing TOA's between the inverted-V and vertical array:

http://users.vnet.net/btippett/new_page_10.htm



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