Topband: K8UR array

[Ron Feutz <feutz@wctc.net>]

Topbanders,

I have long wanted to put a K8UR array (1/2 wave dipole 4-square with 
center fed elements pulled back in at the bottom) or a similar array using 
straight dipole slopers, on a 240' SSV commercial 2-way tower that I 
own.  The tower scales up nearly exactly from the 80 meter array in ON4UN's 
book.  I have a Comtek 4-sq controller that I intend to use.

ON4UN does not show baluns at the feed points; the Comtek manual does.  Are 
baluns necessary?  I would prefer to not use them to lighten the wind and 
weight load on the antenna/tower.

The pattern shown in John's book for the K8UR array has a very broad front 
lobe and a poor front-to-back, making the array a less-than-ideal RX 
antenna.  Is there anyone using one who could give me advice on this?  I 
lease only a small plot where the tower sits, and don't know if I could get 
permission to put RX antennas nearby.

The pattern for the array with straight sloping dipoles shows a sharper 
front lobe and a much better F/B, but it has lots of high angle radiation.
It seems to be a trade off, but my gut tells me the straight dipole sloper 
array would be a better RX antenna.

Is there anyone out there who could model this for me?  It would be nice to 
know the right length for the dipoles at the start, as cut-and-try would be 
a very cumbersome tuning method.

73,

Ron - WA9IRV


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