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A: What is impedance (Z)

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February 22nd 04, 07:35 PM

Richard Clark

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On Sun, 22 Feb 2004 13:07:46 -0600 (CST),
(Richard Harrison) wrote:
Efficiency is output / input.

1/2 or more of the power received by a receiving antenna is re-radiated.

Nearly all of the power received by a transmitting antenna is
transmitted.

Considering the energy available to the antenna, the job done by the
transmitting antenna system as compared with the job done by the
receiving antenna system, the transmitting system is better.

Hi All,

This is because of a shift in the perception of efficiency. To the
transmitter ALL of matched power is irrevocably lost and to the
perception of transmission wholly in-efficient (absolutely no transfer
of power has been engaged to any mechanical benefit). Radiation
Resistance is as lossy as any resistor, sans the caloric benefit of
work.

From the point of view of the wave impinging upon an antenna, only
half the power is irrevocably lost, half survives (in a Zeno's
paradoxical fashion). Again, absolutely no mechanical benefit is
derived except for a incredibly minute caloric gain (unless you test
your antennas inside a microwave oven) but this does invert the
expectation (some work has been accomplished).

Given efficiency is too often stated in terms of mechanical theory
(adiabatics and such) and then duct-taped to other disciplines
(notable through the egregiously wild claims of fantasy laws of
conservation) it is no surprise that other paradoxes emerge.

73's
Richard Clark, KB7QHC

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