On Aug 15, 5:09 am, "amdx" wrote:
Is it possible for a VSWR meter to read 1 to 1 with reactance at the
antenna?
Ex. If the antenna Z was R= 30 and X= 40 would the meter read 1 to 1?
Or is there a combination of R and X that would give 1 to 1?
Thanks for your answer and
explanations,
Mike

Contrary to what I see in other postings, yes, sure it could. This is
very easy to see on the Smith chart. Consider that the meter is
calibrated to 50+j0 ohms (which, by the way, it's not guaranteed to be
"out of the box" when you first get it!). Consider that connecting
the 30+j40 ohm load to the meter are two sections of lossless line.
The section connected to the load is 42.1 electrical degrees of 45 ohm
line, and the section from there to the SWR meter is 87.7 degrees of
82.5 ohm line. That gives you 50.03-j.01 ohms presented to the
meter. Note that 45 ohms is within 10% tolerance of 50 ohms, and 87.7
is a poorly-made 75 ohm line that's out of tolerance. Hey, copper has
gotten expensive, and the manufacturer is scrimping to save a few
bucks.

Likely the meter is NOT calibrated to 50 ohms, and that would allow a
different set of line impedances to achieve a match. With some loads,
you only need a single section of line the right length. For example,
if you said your meter was calibrated to 50 ohms, and the load was
67+j28 ohms, you'd get a 1:1 SWR reading with 42.6 degrees of 75 ohm
line. Note that the actual SWR on that line is NOT 1:1. SWR meters
tell you the line SWR only if they are calibrated to the line
impedance. Reg Edwards always used to rail against calling them SWR
meters, but to me, the name is fine if you understand the need for
calibration, the need to apply them properly.

Cheers,
Tom