[Amps] close to off topic - how to read antenna R + jX ??

[Georgens, Tom]

Dan -

It is my understanding that the RF-1 displays just the magnitude of the impedance vector.  It cannot directly separate the resistive and reactive elements into R + jX.  Instead, it reads !Z! or the square root of the sum of R squared and X squared.  When you measure a pure 50 ohm resistance, the reactance is zero and the Z (what you read) is 50.  When you press the C button, you get the value of capacitor that will yield that magnitude of impedance at the selected frequency.  Likewise when you press the L button. 

To be clear, you cannot directly read resistive, capacitive or inductive components of a complex impedance on the meter unless there is a pure resistance, capacitance, or inductance.

That said, I believe the website has a set of equations from which R + jX can be derived from the Z and SWR measurements.  This is not in the manual.

Hope that helps a little

73, Tom W2SC
-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
Behalf Of Dan Sawyer
Sent: Saturday, February 26, 2005 1:17 PM
To: amps
Subject: [Amps] close to off topic - how to read antenna R + jX ??


All,

I have become interested in leaning more about what is actually going on 
at the antenna. I have a vertical and would like to measure it.

First I have an Autek RF-1. It measures swr, Z, L, and C at a preset f. 
I am not certain what the L and C are reading. When I measure a 50 Ohm 
terminator at 7.2 MHz it actually reads a Z of 50 and an SWR of 1.0. 
However the L and C readings are of 2 uH and 2500 pf.  What are these 
actually measuring? The values are very close to those from the antenna. 

How can I actually measure the L and or C component of the antenna? If I 
use an impedance bridge at the frequency will it measure L (or C)?

I hope this is close enough to topic.

Dan

_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps