[TowerTalk] 40/30 antennas on same mast

[Jeff Blaine]

I have 40 and 30m beams on a single tower and modeling of those shows 
virtually zero interaction.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 15-Jul-18 8:21 PM, DALE LONG wrote:
> Paul
> Perhaps less interesting, but simple, would be a sloping dipole/vertical dipole fastened to the top of the tower.  Unless you have a very short tower, this can be an effective antenna on 30m. I have used them around the world and have been quite satisfied.
> You could also side-mount a single fixed element near the top of the tower.  Both of these ideas save a spot on your mast for some other antenna. When operating in the USA with a single dipole element, there is not a lot of need to rotate it.  Now if you had a 3 element yagi, that would be different.
> 73,
> Dale - N3BNA
>
>        From: N1BUG <paul at n1bug.com>
>   To: towertalk reflector <towertalk at contesting.com>
>   Sent: Sunday, July 15, 2018 9:06 PM
>   Subject: [TowerTalk] 40/30 antennas on same mast
>     
> 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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