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Old October 2nd 15, 06:20 PM posted to rec.radio.amateur.antenna
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Default Short antennae are poor radiators - a simple illustration.

On 9/16/2015 7:58 AM, gareth wrote:
By their very nature, short antennae are standing wave antennae and not
travelling wave antennae.


It is possible to have a short traveling wave antenna, yes? If the
forward power is absorbed by something at the end rather than reflected,
then it is a traveling wave antenna regardless of length. It may be very
inefficient, but that is not the issue, is it?

Consider the standing wave that is apparent when the incident wave arrives
at
the open end of the antennae.


Okay. It is reflected because the current cannot go beyond the end of
the conductor.

In the case of at least 1/4 wave antennae, the standing wave exhibits the
full quadrant
of a cycle, but in the shorter antennae, there is less than a full quadrant,
and it follows
that because not the full quadrant appears on the antennae, then they do not
radiate from that
full quadrant.


That is not a good reason. The signal reflected from the open end will
again be reflected at the feed point and will bounce back and forth
until it is emitted. Yes?

Do you have any technical or mathematical treatments of your assertion
that we can read? Do you have a simulation program? EZNEC is free and
you can show to yourself the efficiency of a short antenna.


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