[TowerTalk] 40/30 antennas on same mast

[N1BUG]

Herb, Yes I have but I consider that an option best left to expert
builders or those who primarily want to experiment. I am unable to
create any model which shows good SWR on two bands with that
approach. In the real world things are even more complicated with
tapered elements.

I have been working on this all day and have created a model with a
split 30 meter element suspended about one foot below the 40 meter
element and fed as a parallel dipole / fan dipole. There seems to be
no pattern distortion on either band compared to a single band
dipole. SWR is tricky but can probably be done with fixed spacing by
adjusting both element lengths. That is easier to do on the tower
than changing spacing. My model may or may not be correct but I am
leaning toward trying this configuration.

Paul


On 07/16/2018 04:59 PM, Herbert Schoenbohm wrote:
> Paul,  Have you considered shock exciting and insulated (sleeve
> principle) 30 Meter element a few inches above the 40-meter
> rotatable dipole?  This would probably work if the 40-meter dipole
> is a split dipole fed with coax directly. Changing the distance up
> or down  will give you the best VSWR on 30 meters.