Roy Lewallen, W7EL wrote:

They'll intercept equal amounts, assuming both are lossless. The
directional antenna will intercept a larger fraction than the isotropic
antenna in the directions it favors, and less in others. The total will
be be the same.

In reverse, this is equivalent to calculating the average gain of the
antennas, which is the same for all lossless antennas.


Roy Lewallen, W7EL



Hello to all, my name is Miguel, LU 6ETJ.

It is a pleasure to read this group. This topic is really an
interesting question...

Modestly I would want to point out the following thing:

Imagine an inner radiant spherical surface with a finite and uniform
density radiant energy.
Aim a directional antenna with a directivity of, for example, one
stereoradian on any direction.
How is it able to such an antenna to receive equal quantity of energy
of a smaller portion of the sphere than an antenna that is able to
receive the energy taken place by the entirety sphere?

73´s of Miguel Ghezzi (LU 6ETJ)

Untranslated text for reference (my written english is a little poor
;( ):

Hola a todos, mi nombre es Miguel LU 6ETJ.

Es un gusto leer este grupo. Este tópico es realmente una interesante
pregunta...

Modestamente desearía señalar lo siguiente:

Imagine la parte interior de una esfera radiante, con una densidad de
energia radiante finita y uniforme.
Apunte un antena direccional con una directividad de, por ejemplo, un
estéreo radian en cualquier dirección.
¿Cómo puede tal antena recibir igual cantidad de energía de una
porción menor de la superficie radiante, que una antena que es capaz
de recibir la energía producida por la totalidad de la esfera?

73´s de Miguel Ghezzi (LU 6ETJ)