Topband: 1/8 wave vertical

[Michael Tope]

----- Original Message ----- 
From: "Tom Rauch" <w8ji at contesting.com>

> That means losses in the earth would be reduced by as much 
> as 50% if they were all due to ground current at the antenna 
> base. That's a big change if the ground losses totally 
> dominate the whole system and most of the transmitter power 
> was being turned to heat. The ERP might go up around 3dB. 
> With a typical mediocre ground the change would be much 
> less. With a very good ground losses wouldn't any noticeable 
> amount at all from the change in radiation resistance.
> 
> It always helps to put the perspective change into real 
> numbers, and we know it is less than 3dB from the change in 
> radiation resistance in a current fed antenna.
> 
> It's certainly possible if we use a bad loading design to do 
> more than 3dB of damage. The GAP vertical is a good example 
> of loss. They worked pretty hard to get the  10dB or more 
> loss  on the lowest bands (the Titan was measured about 16dB 
> below a 1/4 wave vertical on 80 meters). Still, many people 
> are happy with that kind of loss! 16 dB loss makes <3dB loss 
> look unimportant.
> 
> 73 Tom
> 

I think the numbers you are citing above are spot on, but I 
would argue that even even as little 1dB improvement in 
EIRP is worth going after, especially if you are dealing with
a compromise system (as with a small radial field). In most 
cases it won't make any difference, but I've had so many 160 
QSOs that were just on the margin, I can't help but think 
that 1dB shouldn't be neglected.

73, Mike W4EF...................