Topband: Radial requirements for 1/2 wave vertical?

[WD8DSB at aol.com]

In a message dated 2/18/2010 11:12:25 P.M. Eastern Standard Time,  
mrscience65704 at yahoo.com writes:

I'm  certainly not trying to argue with you, Dick; perhaps I'm way off 
base. I'm  not an antenna expert. Why don't we see what the others on the 
Topband list  have to say about the radial requirements for a half wave vertical? 
If I  recall, I don't think that using a 1/2 wave vertical "gets around 
having to  mess with an extensive ground-radial system".
Mike and Dick,
 
I just ran some EZNEC models on a 132 foot vertical Vs. a 264 foot  
vertical operating at 1.82 MHZ, and here is what it says:
 
Perfect Ground (same as lots of ground  radials)
132 foot vertical : Max Gain = 5.15 dbi @ 0 Degrees
264 foot vertical : Max Gain = 6.76 dbi @ 0 Degrees
 
 
No Radials (just a ground rod) with Average Soil Conditions  (0.005 S/m)
132 foot vertical : Max Gain = -3.59 dbi @ 22 Degrees
264 foot vertical : Max Gain = 1.25 dbi @ 16 Degrees
 
 
No Radials (just a ground rod) with Poor Soil Conditions  (0.001 S/m)
132 foot vertical : Max Gain = -6.93 dbi @ 27 Degrees
264 foot vertical : Max Gain = 0.05 dbi @ 19 Degrees
 
I'm using the demo version of EZNEC, so can't do analysis using actual  
ground radials, nevertheless the above analysis is indeed interesting.  It  
shows that the 1/4 wave vertical does indeed suffer more loss in gain as well 
as  a higher angle of radiation compared with a 1/2 wavelength vertical under 
 identical soil conditions.
 
On the other hand if your trying to create a perfect ground condition via  
the use of ground radials, then I would guess that the 1/4 wavelength 
vertical  would offer almost identical performance as the 1/2 wavelength vertical 
without  the need of such long ground radials but this is just based on my 
intuition (no  data or model in hand to support this).  My above numbers also 
do not  reflect any matching network losses, etc.
 
Hope this makes sense, and lets see what others have to say.
 
Don