Topband: Vertical dipoles in the real world

[PaulKB8N at aol.com]

Jim,
 
I put up a short vertical dipole for 40M.  It is 25' tall and has top  and 
bottom X-shaped capacitive hats that are 42.5" square with a perimeter wire  
attached.  The lower capacitive hat is about 6' above the ground.
 
While the antenna is resonant just under 9 mHz, it works very well on  both 
30M and 40M.  My "go-to" antenna on 40M is Double Zepp about 90' on a  
side.  I frankly did not expect this short vertical dipole to be  competitive 
with the DZ, yet it was!  As expected, close-in reports on the  Reverse Beacon 
Network favored the DZ, but there were many distant stations that  reported 
in on the Vertical Dipole that weren't reported on the  DZ.  
 
I've compiled about 10 pages of RBN comparisons of the two  antennas, and 
overall, there is less than a dB difference between the two  antennas on 
common RBN sites, with an advantage to the Vertical Dipole on longer  DX.  
Daytime favors the DZ, nightime the Vertical Dipole.
 
While this is not rigorous science, I am satisfied that I can generally  
replicate the performance of a very successful antenna with a much larger  
footprint with the much smaller Vertical Dipole.  Mine is a wire version  hung 
from a tree and can be deployed
in about 10 minutes.  I'm going to increase the size of the hats to  make 
this antenna resonant on 40M and would expect even better results.   This 
antenna can be very easily fabricated, I'd like to encourage results  from 
anyone trying something similar.
 
Paul, K5AF
 
 
 
In a message dated 9/20/2012 11:00:18 P.M. Central Daylight Time,  
wa3mej at comcast.net writes:



I noticed that some of the DXpeditions are using vertical  diipoles next to 
the sea on at least some of the higher bands ( I am guessing  20 and up).  
I stuffed the data into EZNEC 5.0 and came up with some  suprising results, 
hope I did it correctly I am not an antenna guru . Now as  Tom has just 
indicated modeling is great but its only modeling it doesnt  really tell what 
happens in the real world/ground conditions etc.  



Does anyone have any real world experience with these  dipoles?  Do they 
work in non beach environments such as near the  mountians? Comments 
welcome... and I am willing to take the comments off list  if it suits you. 



If this is not a fools folley I will put  together what I find suprising 
and put it on my web site for everyone to  access but I dont to take the time 
to document it if its a waste of  time.  



Jim  


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UR RST IS ... ...  ..9 QSB QSB - hw? BK