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Stacking multple beams

Wiskey Delta-40

Wiskey Delta-40

W9WDX Amateur Radio Club Member
Oct 18, 2011
468
65
38
Bradshaw Mtns Arizona
Ok the question here is.. When stacking multple beams on the same tower IE: mono band, Is there any set distance that they should be set at apart from each other so that one will not interfear with the other.. Iam NOT looking to cophase these they are going to be MONO band antennas for the different bands..


 

As long as your not going to be using more than one of them at a time I'd be more worried about the wind load on your tower. Your going to need a beefy tower to stack beams.
 
What bands? It is reasonably easy to have manageable stacking distances on VHF and UHF but much harder on HF. What antennas are you planning to stack and what do you have for a tower or mast? There is usually a small compromise to be made when stacking antennas and the goal is usually to minimize interference rather than eliminate it. in the spring I plan to stack as many as six antennas for everything from 20m to 2m on my tower and planning the distances was a REAL PITA. I will have some interference but based on others it should not be that bad.
 
I have 2 towers now.

Rohn 45 and a Tri-ex w51 3 stage crank up. Right now the Rohn has a 5 elemnt tri band and a R7 on it with 18 feet of pipe. The Tri-ex i just got and not set up as of yet..

I was thinking 10-12-15 on the Tri-Ex and 17-20 on the Rohn..
I will get a pic of set up in the AM what I have now
 
I am a bit confused. First you asked about stacking on the same tower and then you say you will be using two different towers? Is that right? If so you will have no problem with interaction especially if they are not at the exact same height. When stacking different bands on the same tower you can put smaller antennas like 2m yagis in between larger antennas like tribanders without that much of an issue. I have to do this on my mast as I have only about 17 feet of mast above the top of the tower but have six antennas to mount. All antennas will be horizontal except the 2m FM antenna.My installation will have an Explorer 14 at 62',an A147-11 at 64' mounted vertically, an A3WS at 66',a 13B2 at 68', a homebrew six element 6m yagi at 73' and another phased 13B2 at 78'. I expect there to be some interaction however by all accounts the spacings I have chosen based on my available mast length should minimize this. In the past i have had the 6m yagi mounted a few feet above an A3 tribander and a 2m yagi about five feet above that and saw very little if any problems.
 
General rule is half the boom length of the highest frequency antenna if it is stacked over a lower frequency antenna.

Let's say you have a 10 meter beam with a 24 foot boom, stacked above a 20 meter beam on a 36 foot boom. You would stack the 10 meter yagi 12 feet above the 20 meter yogi.
 
WA8ZYT said:
General rule is half the boom length of the highest frequency antenna if it is stacked over a lower frequency antenna.

Let's say you have a 10 meter beam with a 24 foot boom, stacked above a 20 meter beam on a 36 foot boom. You would stack the 10 meter yagi 12 feet above the 20 meter yogi.
Click to expand...


In reality you can stack them a lot closer than that without any real bad effects. That old half the boom length theory has been all but thrown out since better antenna analysis programs and info have been available. You now just need to know the field of aperture of the smaller antenna and make sure nothing intrudes much into it.You can come very close to determining that by looking at the beamwidth of the antenna and referring to a little geometry. The smaller antenna will not generally affect the larger antenna to any extent.When stacking antennas for the same band you stack them just far enough apart that their apertures just touch for maximum gain. In the end stacking them as far apart as you can and being on the air is far better than not having them up because you think it won't work well. My close spaced A3, 6m, and 2m antennas allowed me to work all over the world on HF at 38 feet and all over Europe and Northwest Africa and the Caribbean on 6m with 100 watts at 42 feet. The close spacing worked far better than not being up at all. :D


VHF/UHF Long Yagi Workshop

Untitled Document
 
Ok here is what I have up currently

Hygain TH5MM, Cushcraft R7 on top of it and a 13 element home brew 2 meter

 

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I would have no problem mounting that 2m antenna just below the vertical so that the element tips are just below the mounting point of the vertical. Since it is vertical the HF yagi won't even see it and vice versa. Ideally you should use a side arm to mount it a foot or two off side the vertical mast. The additional wind load would be negligible.

BTW does that HB 2m yagi have a trigonal reflector? It does not look like a single reflector element. How is that working for you?
 
CK,
I have a 3rd tower that I will be putting the 2m beam on(40 ft crank up) would like to make another and cophase them.. And yes it is trigonal on the end.. If you mean 3 elements.. Antenna works AWSOME with 15 watts I can key a repetaer 100 miles from me and with the amp on (160 watts) I am full quieting into it.

I think I jumped into this HF/VHF thing since getting my ticket with both feet dont think there any turning back now the bug has bitten me HARD !

It is to bad I want a Masarati on a Pinto budget
 

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