Re: Antenna physical size

Art wrote:
"No where can I find reference to "size" in what the masters state"


More diligence!

Terman never failed to have an answer for me. On page 864 of his 1955
0pus he writes:
"The simplest wire radiator or antenna is the elementary doublet shown
in Fig. 23-1a. This consists of a conductor of length small-delta l that
is short compared with the wavelength lambda, and which is assumed to
have such large capacitance areas associated with each end that current
flowing throughout the length of the doublet everywhere has the same
value I. The strength E of the field radiated from such an elementary
antenna in volts per unit length by a current I cos (omega t + 90
degrees) is given by the formula
E = 60 pi/d l/lambda Icos theta cos omega (t-d/c)
Eqn. (23-1)
Here d is the distance from the doublet to a distant receiving point P,
and theta is the direction of P with respect a plane perpendicular to
the axis of the doublet while c is the velocity of light. The strength
of the radiated field is distributed in space in accordance with the
doughnut pattern with a figure-of-eight cross section shown in Fig.
23-1b."

The above is only the beginning of Terman`s chapter on antennas. Fig.
23-2 shows how contributions from multiple doublets in a larger antenna
combine to produce the pattern of the larger antenna. Point to be noted
is that length over lambda is a multiplier in Eqn.(23-1). Obviously size
(length) does make a difference.

Best regards, Richard Harrison, KB5WZI

.

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