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Old 2-Sep-2012, 12:58 AM   #16
GroundUrMast
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Join Date: Oct 2010
Location: Greater Seattle Area
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Quote:
Originally Posted by thom View Post
Thanks, makes sense.

So I should be able to measure the impedance on the notional DB8e with multimeter contacts on the points where the balun/transformer would attach?

(and likewise with a stock DB4e which would tell me the ratio of its balun)
Unfortunately, no. A Multimeter or DVM is going to apply DC (0 Hz) to the devise when measuring resistance. The antenna operates in the 50 to 700 MHz range... A DVM does not.

An RF impedance bridge is needed... In current practice, you would be looking at an RF Network Analyzer. These types of test equipment generate RF and measure power, voltage or current reflected from the devise under test.They start at around $5000 used.

For poor folks like you and I, modeling with 4NEC2 software then build, test, modify, test... is the cost effective option.
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