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Old 25th Nov 2017, 11:46 pm   #44
kalee20
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Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,087
Default Re: Another Pantry MW Thing

Quote:
Originally Posted by Karen O View Post
Yes Dave, it is standard to express a network as A+jB where A is the ohmic resistance and B is the reactive (capacitive/inductive) component, i.e. as a series combination. Short aerials are almost all capacitive with a tiny bit of ohmic (the 'radiation resistance').
I'm definitely with this, yes! As a complex impedance, Z = R + jX is the simplest way to express it.

But - apart from that it may not be convention - it's equally correct to express a network as a complex admittance, Y = G + jB where G is the in-phase component (conductance), and B is the quadrature, reactive component (susceptance). As a parallel combination. And for a short-wire, G will be very low (equivalent to high resistance).

The big advantage of this is that because the components are in parallel, it is possible to measure the voltage applied to G, whereas the series case, you can't.
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