Topband: Re: Beverage Length

[Bill Tippett]

W8JI wrote:

>I have NEVER had a dipole lower than 200 feet beat the high horizontals
>or my verticals at distances greater than 200-300 miles.

        I've seen this many, many times after sunrise.  In the summer
of 1985 I worked many VK's on SSB regularly around Colorado sunrise.  In
fact, many of those QSO's were with Bob VK3BVS who is now VK3ZL.  He
and the other regulars back then (VK2DPS, VK3AX, VK3HW, etc) surely remember
all my tests!  My two antennas were an elevated Ground Plane (20 radials)
and a dipole (apex ~145' and ends ~100').  At ~.5 wavelengths height a
dipole's signal at 90 degrees up is maximized compared to either lower or
higher positions (you get more ground loss at lower elevations and lower
radiation angles at higher elevations).  

        My results were very consistent:

Time                   Vertical vs Dipole        
      
Sunrise -1 hour        Vertical 1-2 S-units stronger
Sunrise                ~equal          
Sunrise +.5 hour       Dipole 1-2 S-units stronger

        Another memorable case was YB0ARA (a path of 9000 miles from
Colorado) on 13 March 1985 at 1320 UTC...ten minutes past my local
sunrise.  He was completely inaudible on the ground plane or a 1000'
Beverage but very workable and a solid 559 on the dipole.  Had I not
had the dipole, I would not have made the QSO.

        These results were so consistent that I still feel there must
be a very different mechanism at work around sunrise (ionospheric tilt, 
Pedersen rays, or ???) which causes very high angles to work better.  

                                                73,  Bill  W4ZV


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