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Scantenna in office building

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#1
I'm thinking of trying to put a Scantenna above the drop ceiling in my office building. There is about 3 feet of dead space between my ceiling and the concrete deck of the next floor above. The building is your typical steel reinforced concrete with an masonry (brick) outer skin.

My thought was to simply lean it diagonally between the ceiling and the brick so it's not touching anything metal and ... just see what happens. I don't have florescent light banks in the ceiling, just some halogen track lights.

I plan on splitting it into several old Regency M series scanners and a Pro 95.

Two questions, please:

1. Will I need to ground it to the building or do anything besides just attaching it to the radios?

2. Does anyone have any thoughts how it should perform? It's actually going to be fairly difficult and rather messy to install so if it's going to be a total waste of time, I don't want to try it.

Thanks for everyone's input.
 
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#2
I know if it's outside it would need to be grounded, However, I don't know what floor you're on but I take it apparently not the top if there's another concrete floor above you, however, From what I've heard on here and elsewhere as long as there's no chance of lightning getting it I don't "THINK" it has to be grounded but I "COULD" be "WRONG" (Those are italicized and caps for a reason) on that... Someone else should clarify.. Also, As far as working inside all of that, It "SHOULD" but probably not as great as outside, It should pick up locally but I'm not sure. Need someone with experience on this to really get a good answer and I don't have that. Just telling you what I think and what I've heard. Maybe someone else that's more experienced will chime in with the answer here.. But hopefully this helps you out some...to an extent anyway...
 
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#3
You probably answered your own question with all the steel reinforcement in the building and the concrete isnt going to help ya much. You'd be far better off to get something near a window on a filing cabinet or along a window. Hoser
 

KE5MC

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#4
With only 3 feet you are mounting it more in the horizontal even though you are diagonal. It should be mounted vertical for max reception. It will not be deaf in the horizontal, but might not be worth the effort.
 
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#5
Definitely won't pick up the field as good near-horizontal. If it's going to be effort I wouldn't suggest it. In a highly steel/concrete building you'll need something with lots of gain to be of any use.

I second the notion of putting something at a window.
 
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#6
Thanks for all the input. Let me ask you this as an alternate solution:

The best reception I get now is from my Radio Shack mag mount mobile antenna (RS Catalog #:20-032). I can sit in the parking lot of my office building and receive everything I want. But I bring it up stairs to my office and it doesn't do any better than the rubber duck that came with my scanner. I assume that this has something to do with the ground plane that the antenna enjoys by sitting on the roof of my car. Is there a way I can establish a similar ground plane in the building? Or am I totally wrong about it being a ground plane issue?

If I can use that antenna inside, there is a nice corner spot where two windows come together at a 90% angle that should be perfect.

Thanks again.
 
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#7
Like Hoser says a filing cabinet can furnish a sort of 'groundplane' like the car. Honestly-unless you're putting the antenna up in the ceiling to hide it, you'll get best reception nearest a window.
 
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#8
That building isn't the best place to put any antenna inside. I'll say it to you and any of the millions who can't put anything outside, nest to the window works better than anything else. Look at your surroundings, steel girders just do not allow radio waves to penetrate. Thinking that a "powerful" antenna is going to work inside is a pipe dream. Any antenna inside is a compromise, what makes it worse is being surrounded by it's enemy, steel, ductwork, aluminum, making that "powerful" antenna into a wet noodle.
 

trooperdude

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#9
You are losing 3db of signal just by having it indoors. 1/2 your signal strength.

The steel, concrete, brick, etc. probably loses you another 3 db of signal.

Mounting it horizontally to receive vertical signals loses you another 2-3 db of
signal.

You'd be better off using a wet string in this case. You're starting with a net
negative signal strength.

Mobile antenna on metal, near a window, is your only hope of getting much signal
into that building.

The scantenna in this case is a waste of money.
 

KE5MC

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#10
Bring your mag mount inside at the corner will give you a good data point to compare against relative to the parking lot performance. One attenuation point often overlooked is the window itself. With the newer glass in commercial buildings the addition of window tint and heat reflective additive/film it can be a problem depending on the frequency you want to listen too.
 
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#11
The Scantenna I have seen is a dipole. It requires no ground; the top half works against the bottom half like a quarter-wave would work against the ground. My experience inside office bulidings has been pretty negative. All the computers, fluorescent lighting, business machines, etc. just raise the noise floor too much. If you have a corner office, I'd say just to put the radio in the corner and use the telescoping antenna on it for reception. The Scantenna I've seen was over 6 feet long and wouldn't be worthwhile in the ceiling space. If you're not listening to any low-band stuff, you could clip the long center elements off and just use the X-shaped high band and uhf elements. Even then, I think I'd stick with the telescoping antenna or the duck. Bob, WoNXN
 
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#13
This is good input. Clearly the easiest solution is going to be the best.

One more question, please. I can't fit a filing cabinet in the corner. But I could mount a triangular piece of steel (or other metal, but I assume steel would be best) where the two windows meet. I would end up with roughly 85 square inches of ground plane. Not very much, but will it make a worthwhile difference?

Also, I have two thin (1/32") steel plates under the window that I could attach to the triangle with copper wire. Would this add to the ground plane?

See attachments. Thanks yet again!!!!
 

Attachments

KB8KOJ

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#14
3db loss indoors? I would say closer to 20db. That doesn't even include the polarity difference either.
trooperdude said:
You are losing 3db of signal just by having it indoors. 1/2 your signal strength.

The steel, concrete, brick, etc. probably loses you another 3 db of signal.

Mounting it horizontally to receive vertical signals loses you another 2-3 db of
signal.

You'd be better off using a wet string in this case. You're starting with a net
negative signal strength.

Mobile antenna on metal, near a window, is your only hope of getting much signal
into that building.

The scantenna in this case is a waste of money.
 

SAR923

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Messages
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#15
Any steel would be better than none and being closer to a window is better than behind a wall. Why not just bring in the biggest baking tray you have and prop it up against the window with a couple of chairs? If your signal strength improves dramatically, it's worth it to mount a steel plate, although I don't see why you can't make it square instead of triangular. You'd gain a little more area for your ground plane.
 
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#16
You've got a whole heck of a lot of brick in that office. I think the best way to do it would be set up the antennas at home on your roof and stream your broadcast online and listen to it that way.
 
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#17
Jim, the baking tray is a great suggestion. I'll test it with that. I can't make my plane square because everyone (including me) likes to stand in the corner and enjoy my window. A square corner would be at just the right height to poke me in the John Thomas.

Andy, that too is a great suggestion. But's much too high tech for an old guy who plays with Regency scanners. I'm a naturalist. I still use my thumbs to program my hand held.
 
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