On 9 Feb 2005 17:33:28 -0800, "jimbo" wrote:

I know that I want full band coverage 10-160, and I only have 100 watts
from my transmitter. So, I can't have an antenna that "eats" 90 percent
of my transmitter ourput.

Hi Jimbo,

The simple numbers are radiation resistance and Ohmic resistance.
Which is larger? Answer that and you have a simple answer. What are
their proportions? Answer that and you have a more complex answer.
Think of a voltage divider (now a power divider).

Now ask yourself, what is the radiation resistance? What is the Ohmic
resistance? For quarterwave and smaller antennas, simple formulas
abound (or tables are available) for radiation resistance. For Ohmic
resistance, this is a function of materials and construction. In this
last regard, it only takes a loose wire, or screw and this resistance
climbs through the roof.

Let's put that into context. For a 12' vertical radiator operating on
160M, you have a 4/160th's wavelength radiator. Radiation resistance
is running on the order of 1/4th Ohm. If you manage to hold all Ohmic
resistance to that value, or lower (everywhere - in TOTAL) then you
verge on 50% efficiency, or better.

Your Mileage May Vary.

73's
Richard Clark, KB7QHC