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Author Topic: antenna basics  (Read 4985 times)

Brandt

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antenna basics
« on: March 04, 2010, 07:01:05 PM »

This post is regarding the 1/4 wave whip antenna and RG6 coax cable provided with my w800usb.

Could anybody tell me why placing the antenna up in the attic versus the first floor garage would improve internal (in the house) reception?

I could understand how placing a vhf/uhf antenna on your roof would help if it were a line-of-sight issue, but I only need reception in and around the house (the yard as well)

It just seems that motion sensors on the opposite end of the house sometimes don't get picked up by the antenna as my garage is obviously not centered in the house.
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Brian H

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Re: antenna basics
« Reply #1 on: March 04, 2010, 07:25:05 PM »

More obstacles between the garage than up to the Attic position.
Could be closer even if the distance is up at an angle vs horizontal.
If the RG6 is longer to the garage, there could be some added loss in the extra wire used.
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Brandt

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Re: antenna basics
« Reply #2 on: March 04, 2010, 07:29:42 PM »

Well from what I read, there are ways to remedy it with an amplifier and that better antenna from radio shack. I just was unsure of why placing it higher or lower would make any difference. At least if it were in the attic I could center it better, whereas in the garage it is toward the front of the house, but it would be a long cable run.
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eagle

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Re: antenna basics
« Reply #3 on: March 04, 2010, 07:56:12 PM »

I'm no antenna expert but I'm guessing it is because of the zero WAF.

Imagine your spouse's reaction when she sees the antenna hanging from the cathedral ceiling in the middle of the house?  With the coax cable duct taped from the floor and up the wall.  :)

But seriously, I'm guessing it is primarily installed in the attic to hide it from view.

r,
eagle 
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dave w

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Re: antenna basics
« Reply #4 on: March 04, 2010, 08:31:12 PM »

Yeah, and hanging Christmas lights on the antenna didn't improve WAF as much as I hoped.   rofl

I think the attic solution is to get a centralized location in the home. Dry wall, insulation, and studs will attenuate lower frequencies to a degree so it just makes sense to get the antenna above all that and in the middle of the house. $0.02.
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Charles Sullivan

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Re: antenna basics
« Reply #5 on: March 06, 2010, 11:21:20 AM »


Several reasons:
Installation in the attic generally allows a more central location while still being "out of the way".

Insulation in exterior walls often has an aluminum foil moisture/radiation barrier which will block the RF signals.  The same insulation would typically be used in walls between the house and an attached (unheated) garage.

In houses with plaster walls (as opposed to drywall), the plaster is usually applied on metal lath which will block RF signals.

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Brandt

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Re: antenna basics
« Reply #6 on: March 07, 2010, 09:59:29 PM »

I found a 50ft RG6 laying around the house that I can use to replace the 12ft that came with the w800. However what if 50ft is not long enough? Would a coupler attenuate the signal at all between two RG6 cables of the same or different lengths?
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Brian H

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Re: antenna basics
« Reply #7 on: March 08, 2010, 06:15:17 AM »

I doubt a coupler will add much loss over what one longer piece with out a coupler would produce.
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Charles Sullivan

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Re: antenna basics
« Reply #8 on: March 08, 2010, 03:19:38 PM »

Check with WGL but I think the cable supplied with the W800 units is 50 Ohm RG-58U rather than the 75 Ohm RG-6 TV cable.  However the Type F connectors used for either W800 or TV are 75 Ohm connectors. (BNC connectors are designed for 50 Ohm.)  I'm not sure what the results would be using totally RG6 cable, but I wouldn't mix 50 and 75 Ohm cables  to get a longer length.

Edited:  Oops, I'm wrong.  WGL offers a replacement cable for the W800 which they identify as being RG-6.

« Last Edit: March 08, 2010, 03:40:25 PM by Charles Sullivan »
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Brandt

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Re: antenna basics
« Reply #9 on: March 08, 2010, 06:23:39 PM »

yes it is 12' RG6 satellite coaxial cable
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dbemowsk

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Re: antenna basics
« Reply #10 on: March 09, 2010, 06:55:34 AM »

The RG6 they use for satellite is a little better coax too.  It is usually quad shielded cable so there should be less signal loss over long distances even using the coupled cable.

Dan
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