how high is to high
Submitted: Friday, Sep 23, 2005 at 17:12
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sxc_thing
hey guys (girls) just wanted to know how high is to high for a uhf antenna. i live on a small
hill not the biggest around high but not far off so yeah anything would be nice :)
Reply By: Nudenut - Friday, Sep 23, 2005 at 17:14
Friday, Sep 23, 2005 at 17:14
height is might.....
AnswerID:
131537
Reply By: Footloose - Friday, Sep 23, 2005 at 17:49
Friday, Sep 23, 2005 at 17:49
When the loss in the feedline is greater than the gain of the aerial at a particular height then its too high.
When the aerial comes down in the first summer storm then its FAR too high :))
AnswerID:
131545
Reply By: sxc_thing - Friday, Sep 23, 2005 at 18:32
Friday, Sep 23, 2005 at 18:32
thank you. Is there any way i could find out how much i lose etc. digital meter?? i am running a 9db about 30ft high dont wanna go any higher just wanna know is that is a lil to much
AnswerID:
131550
Follow Up By: Nick R - Friday, Sep 23, 2005 at 21:46
Friday, Sep 23, 2005 at 21:46
Got our home one up about 20 or so feet, can pick up a quarry about 140 Ks away just after a high pressure system, the higher you go the more cr@p you pick up, depends how far you want to get. a few years ago from here in south west Vic we got north west Tassie, that antenna was up 60 feet. all that was with low loss cabling.
NickR
FollowupID:
385941
Follow Up By: Mad Dog (Australia) - Friday, Sep 23, 2005 at 22:18
Friday, Sep 23, 2005 at 22:18
Feedline loss at UHF can be brutal especially with cheap cable.Masthead amps are mandatory for radio amatueurs conducting weak signal UHF communciations, I'd doubt you'd want to go that far though. Good quality low loss cable is not cheap in fact it can be just bloody outrageous.
There are lots of sites that have coax specs with which you can work out your theoretical loss. Try this one:
http://www.rfcafe.com/references/electrical/coax_chart.htm
400 Mhz is close enough to UHF cb freqs to give you some idea
50 feet will have half the indicated loss, 200 feet double, you get the picture.
FollowupID:
385946
Reply By: BenSpoon - Wednesday, Sep 28, 2005 at 00:53
Wednesday, Sep 28, 2005 at 00:53
If you search the net for your aerial model, you may be able to get a diagram of the radiating pattern of the aerial- from this you can figure how high you can have it and still have it able to pick up from underneath. Your radio is also often only limited to a set distance away from the aerial before noticeable loss- usually 10m. beyond this you need low loss cable.
AnswerID:
132099