"Richard Clark" wrote in message
...
On Sat, 10 Apr 2004 08:37:09 -0700, Bill Turner
wrote:
Bill

How does a person measure the gain of an antenna?

Jerry

Carefully, I would hope.

Hi Bill,

Your response hardly carries the water for an argument supporting gain
being commonly distinct from directivity.

To answer Jerry's question (he probably already knows how) requires
the total integration of all power emitted by the radiator - not an
easy task (as would confirm Bill's sparse reply) and then measuring
power emitted within small volumes (solid angles of sub-radian
dimension) to compare against the whole.

The most distinctive point to observe about this "gain" is that almost
all the power radiated is lost - "almost" being a patronizing term. A
simple thought problem will reveal this sad fate.

Let us presume you are transmitting 100W with 100% efficiency. Now,
lets further presume that the entire population of the planet is
monitoring you with S-9 readability. That is (let's be generous), 10
Billion receivers. What is the net result of this massive
communication in system efficiency?
0.5%

The antenna in the most perfect of circumstances exhibits an absolute
loss of 99.5W and I could easily bet no one here even pretends to
approach 0.000001% of this.

Now, tell me about GAIN. :-)

73's
Richard Clark, KB7QHC

Wow Richard, measuring antenna gain sounds complicated. I never was good
at calculus.

Jerry