Re: Is this REALLY what a mobile UHF/446 antenna looks like??
Posted: 28 Jan 2020, 13:32
Just something nobody else has mentioned but when building antennas you have to take the velocity factor of the material the antenna is made out of into account, this is because the Signal slows down while traveling through the antenna and you need to correct for this.
This is because electricity travels at different speeds through different materials.
You generally want your antennas a bit longer than the calculated wavelength to account for the velocity factor of the antenna material so I always make mine around 20% oversize for trimming purposes, obviously you’d struggle todo this without a S.W.R meter.
Without an swr meter I would probably buy an antenna because you can’t check the SWR of what you make and your nice Yaesu transceiver sounds faaaar more expensive then a pre-made antenna.
I’ve had great results stacking 3 half waves made from rg58coax with a 1/4 wave ground-planes on the bottom, google coax colinear they’re really simple! But again I can’t stress how important a swr meter is
This is because electricity travels at different speeds through different materials.
You generally want your antennas a bit longer than the calculated wavelength to account for the velocity factor of the antenna material so I always make mine around 20% oversize for trimming purposes, obviously you’d struggle todo this without a S.W.R meter.
Without an swr meter I would probably buy an antenna because you can’t check the SWR of what you make and your nice Yaesu transceiver sounds faaaar more expensive then a pre-made antenna.
I’ve had great results stacking 3 half waves made from rg58coax with a 1/4 wave ground-planes on the bottom, google coax colinear they’re really simple! But again I can’t stress how important a swr meter is
