The 1/6 wavelength is just a rough rule of thumb. For a yagi with a 24
foot boom, the calculator below says the far field starts at 15 feet.
1/6 wavelength is 11 feet. Both are much smaller than the distance to my
nearest power line, about 130 feet.
73,
Scott K9MA
On 4/17/2020 10:24, Eddie Edwards wrote:
Scott,
I think this calculator will be a bit more accurate than your 1/6th calculation.
https://www.everythingrf.com/rf-calculators/antenna-near-field-distance-calculator
Also don't forget to use the full size (either dimeter or length) of the entire
yagi array as Jim Brown pointed out. When I do this for typical 20 meter yagi,
please correct me if I'm wrong, but I get a far field distance of 9.5 meters or
about 31 ft for a typical 20 meter yagi. It still might be this far away if
across the street.
73, de ed -K0iL
-----Original Message-----
From: RFI On Behalf Of K9MA
I believe near field for antennas is generally considered to be about
1/6 of a wavelength. That's only 11 feet on 20 meters.
--
Scott K9MA
k9ma@sdellington.us
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|