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.
Herb, KV4FZ
On Sun, Jul 15, 2018 at 10:06 PM, N1BUG <paul@n1bug.com> wrote:
> I have been trying to model this (using MMANA) but I have a hard
> time getting my head around modeling.
>
> I have a full size 40 meter rotatable dipole which I plan to install
> at 105 feet.
>
> I want to put 30 meters on the same mast if possible. I had
> considered two options but am not sure if there will be problems
> with either or both.
>
> Option 1 would be to add a 30 meter element to the existing 40 meter
> rotatable dipole, making two parallel elements with one a few inches
> above or below the other, common feed. I am not certain how well
> this works on bands that are not widely separated in frequency.
>
> Option 2 would be to put a full size 30 meter rotatable dipole
> higher on the mast. The maximum achievable vertical separation would
> be 10 feet with 40 meters at 105 feet and 30 meters at 115 feet. I
> am not convinced this won't become a two element beam pointing
> straight up!
>
> Has anyone modeled these or similar configurations?
>
> Thanks,
> Paul N1BUG
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