[Harc] SWR VS Resonance

[.]

Howard
Resonancs and minimum SWR are, as you said, NOT the same. Also your comment on match boxes is CORRECT. 
The best way to tune an antenna SYSTEM is to use an old fashioned field strength meter. It measures the field strength as it is radiated.
Meter should be OUTSIDE the "Near Field" effecr 
(I think > 3 wavelengths).
Practical distance is far away as u can see it, or have smme on "give"  you the readinga. 
SUPER for tuning mobile antennas.
Used 2 buy 2 mtr mobile antennas, replace antenna part with a piece of welding rod. 
Keyed on 123.5 mhz, read meter, trimmed 1 inch, keyed, read meter - continue until field strength no longer increases. 
Del W6KOZ


On Wednesday, February 3, 2021 Howard, KB6NN via Harc <harc at humboldt-arc.org> wrote:
I have been trying to put into words why a dipole, resonant on a frequency we want to operate on may not show a 1:1 SWR.  From experience I know that such an antenna does not always show a low SWR, and that the placement of the antenna is important (height above ground, nearby objects, etc.) in determining the SWR of an otherwise resonant antenna.

Also important is the method of feeding the antenna and connecting it to the radio.  I also have been saying that SWR, when measured at the transceiver, is an indication of the match between the radio and the antenna system, not [just] the antenna itself - the antenna system includes anything from the antenna jack on the back of the radio all the way up to and including the antenna itself.

Another thing I say is that the matchboxes commonly called "antenna tuners" are matchboxes, not antenna tuners.  They are impedance matching devices.  If the radio wants a 50 ohm load, the matchbox makes sure that, whatever the actual impedance of the load (antenna system), a match to 50 ohms is obtained.

I found an article that says it better than I can, and has examples: https://hamradioschool.com/good-swr-and-antenna-resonance/

Thanks for reading,
Howard
-- 
KB6NN

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