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Wire_saber
Junior Member
Username: Wire_saber
Post Number: 36
Registered: 4-2015
| | Posted on Sunday, November 22, 2015 - 11:20 pm: | 
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I'm weighing the option to install two 4-element yagis on same tower, one placed 16 feet above the other and offset by 90 +\-5 degrees in the aim (one pointing @180 degrees-south at 38' AGL and the other pointing 90 degrees-east at 54' AGL). Both are fixed (no rotor). Will there be any ill effects in my tx-rx signal? Has someone tried this arrangement and what were the results? Both yagis are 10/11 meters. Their independent use is controlled by a switch |
Press_man
Advanced Member
Username: Press_man
Post Number: 896
Registered: 5-2008
| | Posted on Thursday, November 26, 2015 - 4:10 pm: |
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I wouldn't.
I don't see any advantage and you'll increase the wind load. Use the one beam you have and put the money for the second beam into a good rotor.
73 Pressman
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Tech833
Moderator
Username: Tech833
Post Number: 2340
Registered: 8-2002
| | Posted on Friday, November 27, 2015 - 8:03 pm: |
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At 16 feet spacing, assuming the yagis are horizontally polarized, then there will be minimal effect. I am assuming, only one antenna will be connected to the transceiver at a time. If you plan to run them both at the same time (with a co-phasing harness or similar), then all bets are off.
If you plan to run vertical yagis, then 16 feet spacing isn't enough.
Your radio 'Mythbuster' since 1998
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Wire_saber
Junior Member
Username: Wire_saber
Post Number: 37
Registered: 4-2015
| | Posted on Monday, November 30, 2015 - 12:58 am: |
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Not co-phasing nor trying to squeeze more from horizontal yagis; just worrying about antenna coupling. After fixing my son's Magnum with new wires sent by Cubex, I found an 18' aluminum pipe (boom) from an old pool cover, plus copper wire I had bought, and developed a strong urge to build a quad antenna for my system. Since I will need tower # 1 for the quad, but also wish to keep the yagis, an option is to put both yagis on tower # 2, thus risking unwanted coupling from proximity to each other. From your feedback, I sense that if I separate the two yagis by 16' on the same mast, and offset their aim by @90 degrees, I should experience no signal degradation. Thanks! BTW, if I run into a good used rotor to buy, I will definitely use it on the quad. |
Tech833
Moderator
Username: Tech833
Post Number: 2341
Registered: 8-2002
| | Posted on Sunday, December 06, 2015 - 12:39 pm: |
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"I sense that if I separate the two yagis by 16' on the same mast, and offset their aim by @90 degrees, I should experience no signal degradation. "
That is IF they are horizontally polarized. If you run both of them vertical, then they won't play nicely one above the other with only 18 feet spacing.
If you run them horizontal (with 18 feet vertical spacing) and aimed 90 degrees apart, then the only ill effect is the upper antenna will have a higher takeoff angle than it would if the other antenna wasn't right below it.
If your plan is to use the 18 foot vertical spacing with vertically polarized directional antennas, then do it with the quads. They won't interact as much as yagis.
Your radio 'Mythbuster' since 1998
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