[NLRS] 432 sprint and antenna stacking question

[Mike Cizek W0VTT]

Thanks for posting that, Bill.  This is the best explanation I have seen for
interaction between closely spaced antennas.

I have one question about calculating degradation when one antenna is within
another's capture area.  Do you look at the antennas in a 2 dimensional
plane?  i.e., calculate the area of the boom as seen from the end, and the
length of one element?
OR - do you need to look at is as 3 dimensional and include the surface area
of EACH element, like you do for wind load?  I' trying to squeeze my VHF
antenna in between a couple of HF antennas.

----
73,
Mike Cizek W0VTT

-----Original Message-----
From: nlrs-bounces at mailman.qth.net <nlrs-bounces at mailman.qth.net> On Behalf
Of Bill ND0B
Sent: Sunday, 25 April, 2021 11:36
To: 'Mary Brown' <maryalanab at gmail.com>; 'NLRS' <nlrs at mailman.qth.net>
Subject: Re: [NLRS] 432 sprint and antenna stacking question

Hi Mary,

I used this is guidance when I put up my antennas.    

https://directivesystems.com/information/tech-notes/multiple-loop-and-yagis-
on-one-mast/ 

I have 6m, 222, 2m, and 432, in that order, stacked on the same mast that
extends about 15 feet above the tower.   It is definitely not optimal but
does provide enough isolation that I have yet to pop a preamp.    Part of
the spacing was mechanical issues, the 6m and 2m antennas both have guying
systems so the 222 antenna was placed just above the 6m guy mount, the 2m
was spaced down from the top such that there was room for the 70cm antenna
above it.   This arrangement did not flagrantly violate any of the guidance
DS offered and it seems to be working as I have yet (emphasized) to pop a
preamp.  

73 de Bill ND0B



-----Original Message-----
From: nlrs-bounces at mailman.qth.net <nlrs-bounces at mailman.qth.net> On Behalf
Of Mary Brown
Sent: Friday, April 16, 2021 4:30 PM
To: 'NLRS' <nlrs at mailman.qth.net>
Subject: [NLRS] 432 sprint and antenna stacking question

I will be on for the sprint from en24gp.

 

And question on stacking. I need to put 222, 432, and 23cm on one tower.

 

Antenna and half stacking distance

222-10ez 3' 3" half stacking distance

432-9wl 3' half stacking distance

23cm35x4 on an H frame 1' 2 1/2" half stacking distance

 

Thoughts were 222 on the bottom 2' above the tower

Then 23cm35's 4'5" above that

Then the 432 antenna 4'2" above those

 

According to DX Engineering mast load this will survive 120mph. 

 

Thoughts? Going to be running power on 432 with 750 watts and 23cm with 550
watts,  so interactions? Preamp issues from the RF fields? Preamps will be
below tower top so it will just be whatever the antenna picks up from the
other bands.

 

Would love to space this more but this is going on a bracketed Rohn 25 on
the side of the house. right at max wind load. 

 

Mary

W0AAT

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