[Elecraft] OT: Ground Loss (long)

[Jim Brown]

On Sat,7/25/2015 10:16 AM, dyarnes wrote:
> I also have one of N6BT's Bravo 7 antennas, which he calls vertical 
> dipoles also.  By the way, N6BT also designed the Sigma 40KX when he 
> owned Force 12. Anyway, the Bravo 7 works pretty well as a portable 
> system, but I'm not quite as happy with it as a 40 meter system.  
> Still, it is very portable, and easy to put up and take down. 

N6BT's verticals ARE vertical dipoles, loaded in some quite innovative 
ways. W6GJB and I are building an 80M vertical dipole for FD and CQP 
based on some of Tom's ideas.

> N6BT makes some pretty aggressive claims about the performance of this 
> system, but I am pretty sure most of his "testing" was done over salt 
> water. 

I've not known Tom to "puff" his antennas with exaggerated claims. He's 
a very good designer, and my experience with him is nothing but 
honesty.  It is, however, well known that verticals work awfully well 
over salt water, and he's written extensively about that.

> In any event, the higher up I deploy that system, the better it seems 
> to work.  I think Jim Brown's suggestion of adding a better radial 
> system to vertical dipoles may be exactly what I need to try and do 
> with the Bravo 7, particularly for 40 meter operation.

After having done some more modeling, I'm backpedaling on that 
suggestion. You'd need a LOT of radials over pretty awful ground to see 
a dB or so.  Note also that the horizontal elements at the bottom of 
Tom's vertical dipoles are NOT radials, they are capacitive loading for 
the bottom half of the dipole. Don't try to add to them -- you'll detune 
the antenna. :)

73, Jim K9YC