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Old June 17th 04, 04:37 AM
Richard Harrison
 
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Cecil, W5DXP wrote:
"Someone modeled it the other day and even the modeling program
indicated that the current was sky high at the shorted end of a 1/4 WL
stub."

Agreed that the resistance of the short is small and allows a large
current even when the volts are low. The small load resistance, ZL is
transformed into another resistance, ZS that is inversely proportional
to ZL. Terman expresses this in equation (4-31) as:

ZS = Zo squared / ZL

So, the smaller ZL, the larger ZS. As ZL goes to zero, ZS goes to
infinity.

A high impedance means: accepts little current for a given voltage. The
open end of a good 1/4-wave short-circuited stub is defined as a high
impedance. So much so that it is also called a "metallic insulator".

Best regards, Richard Harrison, KB5WZI

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