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Multi antennas

DragoSapien

DragoSapien

KF5AEJ
Dec 28, 2008
64
0
16
58
Ft.Stockton, Tx.
I have a 35' pole that I plan on putting a dual band 2m/70cm antenna on the very top, a CB antenna just below that off to the side about 4", and my TV antenna lower then that. My ? is, will these three antenna's interfere with each other being on the same pole. :confused:
 

Absolutely. Putting your CB antenna on the same mast as the TV antenna? Yikes!!

Since everywhere in the US is going digital; don't you have a digital optimized antenna?
I would put the CB antenna on the top of the 36 ft point, and run the TV antenna on another. The proximity of the two would still cause interactions - IMO.
As far as the third 2m/440 antenna is concerned, it doesn't really need to be as high. Ten ft over the building should be plenty...
 
okay, Lets throw the CB antenna out of the mix for now and leave the TV antenna on the very top where it is right now. After all, my TV signal comes from 90 mile's away and its the old analog kind. Have to get the new converter that go's inside for digital signal. And put the dual band just above the roof. Would that be better. And what distance should I put the CB antenna from the TV.
 
You are asking me how far one should place new born babies from hungry alligators.
First of all, everybody that isn't using cable will have to get a converter box. Will the old antenna work? Yeah; but does it use coax or 300 ohm tape wire? The coax TV cable won't eliminate bleed over, but it will help some. When you key up your CB or 2m radio - the proximity alone will bleed over if your ground system isn't top notch. Even then, if everything isn't considered like filters and such - using the TV and a radio will have problems.

The CB antenna NEEDS 36 ft above the surface of the ground to the coax feed point for optimal results. Your TV antenna is directional and needs to be high enough to get a good signal. The 2m/440 antenna just needs to be on the roof for best results. The ground system needs to be top notch to keep everything working at its best and to remove interference problems. Putting everything on one mast is asking to do too much to make any one of them work right.
 
I have a different opinion. I'd put that 2 meter/440 antenna on top, the TV antenna under it and the CB antenna as far away from them as I could get it. I like the baby and alligator thingy! Of course, give it about 10 years and you might as well start worrying about the alligators.
- 'Doc
 
WOW!!!! Ha,Ha. I'm glad i asked. I have satellite TV and only use the TV antenna for local news. The pole has excellent grounding. I guess ill just put me up another pole for the dual band. Thats the mean one anyway.
 
Let me ask one more question on this. Dose the length of the coax cable make any difference or dose the antenna need to be close to the radio's location as passable.

And thanks to all of you for putting up with my newbie ?'s
 
The only, or biggest concern with coax length is, will it reach between radio and antenna conveniently? Especially with VHF/UHF stuff, you want as little loss as possible, but there are rea$onable limit$ to that. With the height you're talking about, figure something like for a 100 feet of feed line for that loss factor. It'll be less than that, but it makes for easy figuring. Until that loss gets close to 3 dB, it's just not worth wasting any worry on. (Of course, if you just happen to have some 4" nitrogen filled hardline laying around, use it!)
In other words, no, it doesn't matter.
- 'Doc
 
I'd probalby put the VHF/UHF on top of the TV antenna also. Of course I don't know what type of TV antenna you're using. If it's one of those log periodic type, it could act like a capacitance hat if it's over the top of the vertical vhf/uhf.

The length of the coax doesnt' really matter up to the point where it's so long that you start to introduce a lot of feedline loss, which can be a concern on vhf/uhf.
 
On top goes your VHF/UHF ..

What type of coax are you using..
I would suggest using nothing smaller then LMR-400 coax..

Regarding how long your feedline should/needs to be..
The shortest needed to get the job done is the best to use..
(nothing lass and nothing longer is needed or suggested)
 

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