On Tue, 26 Apr 2005 21:09:07 -0700, Roy Lewallen
wrote:

I believe "takeoff angle" is in the same category as "capture area" and
"S-unit" -- terms which nobody except amateurs seem to need.

Hmmm,

Capture area of antennas, 899, 927 of Terman's "Electronic and Radio
Engineering. The 899 reference appeals to aperture. The 927
reference gives a value of 1.5 or 0.12 lambda² (also called intercept
area or antenna cross section) for a common dipole.

Using the co-equivalent aperture, from "Fields and Waves...," Ramo et
al., 581, 607-623. The 581 reference is to using reflectors and
lenses. The section length treatment relates to literal openings
masking a source of radiation.

Capture area, 255, 298-301, 495-496 from "TV and Other Receiving
Antennas," Bailey - which basically reduces a standard half wave
antenna's area to being one half wave long by one quarter wave in
width. When we look at the math offered in a later chapter (pg 299)
it reduces to 0.12 lambda² a figure already described by Terman. "As
we said before, the use of discrete boundaries is a matter of
practical convenience." However, Bailey offers a treat in presenting
the "capture area" of Arrays of various sizes:
# elements Area (lambda²)
1 .125
2 .25
4 0.5
and so on (naively presuming a 3 dB gain with each doubling of
elements).

As these first three draws off the library shelf have companions on
the same shelf with similar coverage, further examples would be
redundant.

The terms of S-Unit and Take-off angle are more an issue of
researching commercial and retail sources than academia. There is
some element of elitism in this; but having found that there are
volumes of instruction to be found in the commercial world that are
barely revealed in the ivory towers, I am not necessarily impressed
with sterile pedigrees (the IEEE dictionary is a monument of
impotence).

73's
Richard Clark, KB7QHC