[TowerTalk] 15 meter decoupler

[Dan Zimmerman N3OX]

>By adding roughly 2 metres to the base end, it becomes ¾ wavelength on 10
>metres.

Three quarters of a wavelength is too long for DX work.  I know it's
funny, but 0.7wl is OK, 0.75WL has high angle lobes.

It probably doesn't matter much on 10m when the band is open, because
the band's going to be open long and loud, and even if most of your
power is going at an angle of 49 degrees (and into space), you're
still going to have enough at low angles to make plenty of contacts.
This is especially true over saltwater where the low angle lobe is
going to be quite strong, but you'd be stronger  with a shorter
antenna.

The low angle response of a 3/4 wave vertical is down about 4dB from
the response of the slightly shorter vertical.

73,
Dan