144 yagi and 432 yagi stacking distances

[mr_fx]

My actual question is near rhe bottom of this post

I have a ham iv that is mast mounted... using the mast adapter...

The specs on the rotor with no support is 7.5 square feet windload and not more than 3.5 feet above the rotor

I have in the past mounted up to 9 feet above a ham iv... at that time I was mounting a 6m moxon on top (@ about 1sq ft windload), a cushcraft a144-11 mounted in the middle (2m, 1.25 sq ft windload), an an m2 432-9wl (432mhz, 1.6 sq ft windload) mounted on bottom...

Now on to my question...

I will be mountin on this same ham iv, with an aluminum mast

I will be mounting the following antennas:

M2 432-9wl (432mhz, 21ft boom, 28 elements, 1.6 sq ft windload)

http://www.m2inc.com/amateur/432-9wl-420-440-mhz/

And

M2 2m12 (2m, 20foot boom, 12 elements, 1.5 sq ft windload)

http://www.m2inc.com/amateur/2m12/#PhotoSwipe1465930197406


What is a good compromise to mount them with hortzontal polarization where they wont be too much stress on the rotor and not interfering much with each other?

 

[Robb]

Jeopardy answer: half the wavelength of the longest wave of the two freqs. Which should be about 1m.
Did I win the refrigerator?

 

[Captain Kilowatt]

Jeopardy answer: half the wavelength of the longest wave of the two freqs. Which should be about 1m.
Did I win the refrigerator?

Nope. First of all it is one half the boomlength of the longest wavelength antenna so for a 20 foot boom that would mean 10 feet. The wavelength of the band in questiojn does not enter into the equation and even if it did that figure has been thrown about for years but is not right. The real answer is to stack them so that their apertures do not overlap and depending on yhe antennas that boom length answer can be way off. I have a good article that explains stacking distances for same band or different bands at home. I am at work now but will try and find a link to it later tonight when I get home and find the article.

 

[Captain Kilowatt]

Found it.

http://www.ifwtech.co.uk/g3sek/stacking/stacking2.htm

 

[Captain Kilowatt]

One sure fire way to get it right is to consult the manufacturers data on stacking distances for EACH antenna. They have already done the aperture calculations for you.If they say that the 2m antenna should be stacked 10 feet apart and the 70cm antenna should be spaced 5 feet apart the take one half of each and add them together. In this example it would be 5+2.5=7.5 feet.

 

[vkrules]

Sorry Robb prize goes to CK