Standing wave on feeders
 

David wrote:
Is the current sinewave on the feeder a standing wave?

Standing wave current is usually drawn as an envelope
using maximum absolute values. If the current is drawn
as a sine wave, it may be a snapshot of a traveling wave.
A snapshot of the traveling wave on 50 ohm coax feeding
a 50 ohm antenna would be a sine wave.

The Balanis diagram is definitely standing waves
as it is NOT a sine wave but rather an envelope
of maximum absolute values. And it also is not
100% accurate as the current envelope is a
perfect half circle.
--
73, Cecil http://www.w5dxp.com

Standing wave on feeders
 

Richard Harrison wrote:
David wrote:
"Antenna is resonant and presenting good impedance. SWR is 1:1.
If the feeder is coax, is there a standing wave on the coax?
If the feeder is open wire, is there a standing wave on the feeder?"

SWR is 1:1 means the line is flat. The line matches the antenna
regardless of configuration. There is no reflection from the load.
Standing waves are produced by a combination of a reflected wave with
the incident wave. No SWR means no reflectiion if coax, open wire, or
any other feedline configuration is in use.

Perhaps what David is actually saying is that the
50 ohm SWR meter reads 1:1 in both cases?

If a 50 ohm SWR meter reads 1:1 looking into open-wire
line, there is an SWR on the open-wire line of ~12:1,
i.e. 600/50.
--
73, Cecil http://www.w5dxp.com

Standing wave on feeders
 

I miswrote:
"No SWR means no reflection-----."
No SWR would be no signal. SWR is the ratio of maximum to minimum
voltage or current on a line. On a flat line, the ratio is 1:1. I meant
to write: No standing wave means no reflection.

Best regards, Richard Harrison, KB5WZI