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@thepoint.net [mailto:n8de@thepoint.net]
Sent: Friday, March 06, 2009 1:34 PM
To: jtml@vla.com; John Lyles
Cc: towertalk@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@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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