About Us

September 27th 05, 02:59 AM

On Tue, 27 Sep 2005 01:36:15 +0000 (UTC),
wrote:

Owen Duffy wrote:
On Mon, 26 Sep 2005 21:39:27 +0000 (UTC),
wrote:

Jim, that seems inconsistent with your earlier statemetn "No, the SWR
being measured is on the load side of the meter."

The load side is the side with the load, i.e. the antenna, on it.

In the example you quoted with a 100 ohm load on a 100 ohm line, were
the line loss low, and the line long enough to be sure to sample a
fully developed voltage maximum and voltage minimum it would be found
that the VSWR was 1:1.

Not for a 50 Ohm system, i.e. a transmitter expecting 50 Ohms and a
meter calibrated for a 50 Ohm system.

I am sorry Jim, the VSWR is a property of the transmission line and
its termination, and the VSWR on that 100 ohm line with a 100 ohm
termination is 1:1. The VSWR could be *MEASURED* on that line by
sampling the magnitude of the voltage at different points on the line
and it would be found that the magnitude of the voltage was constant,
which means VSWR=1:1.

No, the measured SWR is relative to the design impedance of the SWR
meter which is normally 50 Ohms.

The SWR on the line depends on the characteristic impedance of the
line and the impedance of the termination of the line. 50 ohms does
not come into it.

The SWR on your proposed 100 ohm line with a 100 ohm termination is
1:1. If your measurement indicates anything else, then you need to
consider your measurement as invalid.

Owen
--

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FS: UHF Duplexers and Cavity	[email protected]	Swap	0	August 23rd 05 12:28 AM
FS: Icom RP-2210 repeater with 4 cavity duplexer	Tim Walker	Equipment	0	August 22nd 04 06:39 PM
help identify: Varian VMC-1680 (5.5 GHz oscillator; Magnetron? Klystron?)	peter dingemans	Homebrew	5	June 24th 04 04:32 AM
FS: cavity for 829 tubes	Scott Dorsey	Boatanchors	0	February 27th 04 12:55 AM
Fuel Tanks and Cereal Silos as Cavity Resonators for HF	SpamLover	Homebrew	10	October 8th 03 08:13 PM