Initially, nothing but 40/30 will be on the mast. At a later date I
plan to add some UHF yagis but the booms will be at right angles to
the 40/30. I expect little to no interaction with those.
I will try EZNEC but am limited to 20 segments. Perhaps 10 segments
per dipole will be enough for the case of two separate fed antennas.
If I could even begin to get a sense of future competency I wouldn't
mind buying software.
Paul
On 07/15/2018 11:43 PM, john@kk9a.com wrote:
> I am not familiar with MMANA but this is quite easy to model using EZNEC.
> There is no need to model your exact tubing diameters, certainly there must
> be a dipole example that you can alter. I doubt that there will be much
> interaction. What else is on the mast?
>
> John KK9A
>
>
> To: towertalk reflector <towertalk@contesting.com>
> Subject: [TowerTalk] 40/30 antennas on same mast
> From: N1BUG <paul@n1bug.com>
> Date: Sun, 15 Jul 2018 21:06:11 -0400
>
> 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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