[TowerTalk] 6M yagi above a tribander

[Grant Saviers]

Just came across an interesting picture re the TH11 question

Slide 66  of 
https://wwrof.org/wp-content/uploads/2016/03/WWROF-WEBNAIR-RX-Antennas-for-a-Small-Lot-.pdf

A horizontal Waller Flag with interlaced 6m beam above a TH11!  That is 
A LOT of 6061!

Grant KZ1W

On 1/8/2022 08:35, Grant Saviers wrote:
> My experience with a DB36 and 80 shorty dipole cause me to believe that 
> linear loaded yagis can be significantly affected by other antennas on 
> the same mast.  My dipole was both element aligned and boom aligned at 
> 11 ft separation and significantly disturbed the DB36 on 30 and 40m.  20 
>  > 6 there is very little interaction.
> 
> Off course every antenna combination will be different.  JK antennas 
> advertises for a couple models that they are not sensitive to others. 
> Modeling is a way to get an answer, more difficult with trapped antennas 
> when the trap models might be hard to find.  Then the question is what 
> interaction and how much of it (G, F/R, F/S, SWR) is acceptable?  My 
> modeling experience is that a good swr doesn't tell you much about the 
> other three, but a bad swr means something is amiss in them.
> 
> Some no/low interaction counter examples also exist - my 4L steppir with 
> add on 6m elements on the same boom.  Because of almost 2x the height 
> for my 4L, with the add ons, performs essentially as well as a 6m M2 
> 6M5XHP 5 over 5 stack at 38/53ft. So with some hard work and luck re 
> where elements can be placed it is conceivable a 6m 5 element could be 
> interlaced on a TH11. Separate feedlines make such designs easier.  The 
> 3 and 5 band no trap interlaced beams are awesome engineering works of 
> art IMO, having tried modeling of a couple of them I'd like to build.
> 
> Also, the more separation likely the lower the interaction.  The VHF 
> literature has much to say about stacking re capture area.  As a 
> practical matter, plot the swr for each HF band before and after putting 
> up the 6m. Then worry or not.  The wind load from either is low so your 
> tower may allow a mast extension.
> 
> Grant KZ1W
> 
> On 1/8/2022 07:27, mike stokes wrote:
>> I have the same question except that I want to use a 5 Ele 6 and a TH11.
>>
>> I appreciate thoughts for both Pete and my questions.
>>
>> 73
>> Mike
>> KK9V
>>
>> On Sat, Jan 8, 2022 at 10:09 AM Pete Smith N4ZR <pete.n4zr at gmail.com> 
>> wrote:
>>
>>> I have just bought a 3-element 6-meter yagi (Cushcraft), and plan to
>>> mount it above a C-3E tribander.  Would a quarter wave spacing above the
>>> tribander be sufficient (5 feet), or do I need more?  I'll likely just
>>> have one convenient shot at this when I have the rocket launcher down
>>> this spring, and I'd like to get it right from the start
>>>
>>> -- 
>>> 73, Pete N4ZR
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>>
>>