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Old September 14th 15, 04:37 PM posted to rec.radio.amateur.antenna,uk.radio.amateur
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First recorded activity by RadioBanter: Jun 2006
Posts: 1,898
Default the short antenna, matched to its feeder, that returns power to its source.

In rec.radio.amateur.antenna gareth wrote:
Taking one's cue from the Alford Slot Antenna, let us propose the use of the
fields in
the air gap of a parallel plate capacitor as the source of RF radiation.


Slot antennas get added to the list of things Gareth doesn't understand.

A parallel plate capacitor is nothing like a slot antenna of any kind
and does not radiate like an antenna.

To do this, we will terminate our 50 ohm coax


Slot antennas are fed with waveguide.

with a series LC circuit of 50
ohm
resistive impedances (so one will be 25+jX and the other 25-jX) at the
operating
frequency.


That would be two 25 Ohm resistors, one of which is slightly capacitive
and the other slightly inductive.

Very little of the energy supplied to our antenna will be radiated,


This part is correct; it will mostly be heat dissipated in the two
25 Ohm resistors in series.

and most
will be stored
as energy in the resonant LC circuit,


Nope, dissipated as heat in the resistors.

until such time as the stored energy
outdoes the incoming energy,and
the LC circuit will now act as an energy source, sending it back down the
coax.


Series LC circuits get added to the list of things Gareth doesn't understand.

So, we'll have a short antenna, matched to its feeder, that is not radiating
all the power fed to it, and
is returning some of that power back down the coax.


Gibberish.

(An even simpler case, although it would give a reactiv match, would be the
capacitor alone, but think
for one minute, why do you get the 90 degrees phase relationship between the
volts and current
in a capacitor? Because it acts like an energy source in its own right!


For a quarter cycle for AC.

Capacitors get added to the list of things Gareth doesn't understand.


--
Jim Pennino
 
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