[TowerTalk] [re: TowerTalk] 40/30 antennas on same mast

[Martin Sole]

4NEC2 is free :-(

Several hundred segments, built in optimiser


Martin, HS0ZED


On 16/07/2018 17:50, N1BUG wrote:
> 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 at 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 at contesting.com>
>> Subject:	[TowerTalk] 40/30 antennas on same mast
>> From:	N1BUG <paul at 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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