[TowerTalk] impedance measuring antennas

[W5LT]

Accurate measurement of the antenna from the shack depends on the
instrument. With a VNA (Vector Network Analyzer) and the short, open,
termination procedure it calibrates out the cable and refers the measured Z
to the end of the coax.  The AIM-4170 and all lab grade VNAs can do that. 
Bob, W5LT

-----Original Message-----
From: n8de at thepoint.net [mailto:n8de at thepoint.net] 
Sent: Friday, March 06, 2009 1:34 PM
To: jtml at vla.com; John Lyles
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] impedance measuring antennas

Isn't it a bit difficult to haul all that up to the top of a tower to  
make measurements?
Measuring at the shack end of coax is NOT measuring the antenna.
Don
N8DE

Quoting John Lyles <jtml at losalamos.com>:

> I still haven't invested in one of those portable units. i love my   
> Delta Electronics OIB-2, that can measure the Z while 1 kW is   
> transmitted to the antenna. Also, an Hp8751A network analyzer that I  
>  got on EBAY few years ago. With these two, there is little doubt in  
>  the reading. Lab grade, sure.
> John
> K5PRO
>
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