art wrote:

When one looks at a.radiating array pattern one can see that the yagi
is very inefficient. Does anybody know of the relative volume
contained in the main radiation lobe versus the total volume of the
entire
pattern? I know there are a lot of different type antenna gains and
arrangement but I am trying to determine in an informal way the
efficiency
ratio and compare it to what would appear to be a very efficient
antenna
such as a dish. A casual look at a yagi radiation pattern would suggest

that it is less than 50% efficient at best especially when considering
DX work
where even the main lobe is less than 50% efficient when looking at
available
signal paths beyond 4000 miles which are somewhat below 12 degrees and
where the main lobe itself is centered between 13 and 14 degrees with
an
average amateur antennah
Art


Ok, I reread the original post, and it is right here.

The problem is that you need to understand that the angular center of
the main lobe is dependant on the height of the beam above the ground,
so this part -

where the main lobe itself is centered between 13 and 14 degrees with
an
average amateur antennah

is actually a variable.

Here lies your problem.

tom
K0TAR