Attic Antennas

[perrybucsdad]

I just purchased and installed a new Diamond NR770HBNMO antenna and K412SNMO hatch back mount yesterday and I am so pleased with the reception that I am getting. I will have to wait until I get my ticket to see how well my VX6R does with the local repeaters, but at only 5 watts, I know I may be disappointed. We will see.

Anyhow, this has me starting to think about an antenna on the house. I have a homeowners association that we belong to, and nothing in there states that I can't have an antenna, but I know my XYL has indicated that she does not want one on the outside of the house (or in the yard) and I just don't feel like dealing with any issues that it may create. I have a fairly large attic space that can be used I have this nice PVC pipe that runs from the attic all the way down into the basement for any wires that may need to go between the two. This is perfect as I plan to have my shack down there.

Anyhow... what should I be looking at for an attic antenna? I primarily will be working the 2 meter & 70cm bands, but am also looking at a quad band transceiver that will allow me to do the 6meter and 10 meter bands as well.

Thanks for your help...

John

[n9mxq]

Look at Ventennas. Fit over and look like vent pipes that stick out of your roof anyways.


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[perrybucsdad]

Thanks, but I'm really looking for something that I can place in my attic. I'd prefer not to drill holes in my roof if I don't have to.

[n9mxq]

I've run attic antennas with some success.. My best was a Larsen 2/70 NMO mounted to an old computer case shell with radials screwed to it. Was OK for local stuff (repeaters, in town simplex) but that's about it.

The main problem is the shingles and any wiring reflect the signal back. Best you can do is cobble something together and see what works. Just make sure the antenna has some kind of ground plane.. Pizza tin, old sheet metal etc...

[perrybucsdad]

I had someone tell me (and I don't know if this would work or not) to just run wire all over the place in the attic and then wire it to the radio somehow. That just sounds crazy to me for starters.

[n9mxq]

For receive only that would be fine. But I wouldn't put a signal into it

[N1BHH]

Placing antennas in an attic can be a bit of a problem, especially when building materials can be attenuators and because of wiring and HVAC material. I have gotten by with putting antennas up in trees and running coax underground in some cases. You can be real imaginative and inventive if you put your mind to it. I use magnetic mount antennas on the air conditioner and get by quite well and happy with the results.

[perrybucsdad]

OKay... thanks.... I don't have any HVAC in the attic at all... just rafters and insulation and regular asphalt tiles on the roof. There is some electrical wiring for the light in the attic and I think a few others, but not a whole lot. At one point there is about a 15 foot high area above our foyer that I thought would be a great spot to place a taller antenna of some sort. Don't they make some tripod mounts that might work for this, and would the tripod mount then be considered the grounding plane?

I don't have an issue with using a magnetic antenna if that will work, but being that I live about 40 miles out of the metro Cleveland area, I'm concerned if I will get the range that I need. There are a number of repeaters in my county which are a lot closer that 40 miles (but I don't know the exact placement so I don't know the true distance to them).

[n9mxq]

The tripod would work, but I'd still string a counterpoise off each leg. It sure won't hurt. With 15 feet of space you have a lot of options.

[perrybucsdad]

String a counterpoise off each leg? I'm not sure what that means... sorry... I'm still learning. Does that have something to do with grounding?

[n9mxq]

Attach a wire to each leg, stretched out along the floor. It will act as the groundplane for the antenna.

http://en.wikipedia.org/wiki/Counter...ound_system%29

[LtDoc]

The 'hardest' part about indoor antennas is finding a place where they will 'fit'. An indoor antenna isn't going to perform as well as an outdoor antenna simply because there's more 'stuff' between it and the arriving signal. But, an indoor antenna is certainly better than nothing, right?
All antennas have two 'parts', or two connections. If there's only one connection then current doesn't flow and there's no signal. The 'other half' of an antenna doesn't have to be very distinctive, 'separate', or noticeable. In some cases, the 'other half' is the feed line it's self. That 'other half' is usually called a 'groundplane', or counterpoise, or several other names. It can get confusing! If there's no 'other half' supplied, then you have to do the supplying. For a vertical antenna that usually means where the braid of the coax is connected. That 'other half' has to be an electrical conductor. It also has to be related to the wave length of the frequency desired, which changes with the frequency. Higher frequencies need less length, lower frequencies need longer lengths. (Having 'too much' is better than having 'too little' to some ridiculous extent.)
That area you spoke of, the 15 feet high area, would seem like a pretty good place to put an indoor antenna. It should certainly be adequate for most VHF/UHF antennas. There are several ways of doing the mounting. Whichever way you might use needs to support the antenna mechanically and leave space for it's 'other half' too.
Good luck.
- 'Doc

[KS4VT]

Originally Posted by perrybucsdad

I just purchased and installed a new Diamond NR770HBNMO antenna and K412SNMO hatch back mount yesterday and I am so pleased with the reception that I am getting. I will have to wait until I get my ticket to see how well my VX6R does with the local repeaters, but at only 5 watts, I know I may be disappointed. We will see.

Anyhow, this has me starting to think about an antenna on the house. I have a homeowners association that we belong to, and nothing in there states that I can't have an antenna, but I know my XYL has indicated that she does not want one on the outside of the house (or in the yard) and I just don't feel like dealing with any issues that it may create. I have a fairly large attic space that can be used I have this nice PVC pipe that runs from the attic all the way down into the basement for any wires that may need to go between the two. This is perfect as I plan to have my shack down there.

Anyhow... what should I be looking at for an attic antenna? I primarily will be working the 2 meter & 70cm bands, but am also looking at a quad band transceiver that will allow me to do the 6meter and 10 meter bands as well.

Thanks for your help...

John

I use the AR270 antenna in my attic and it works just for for local operations in the attic of my 2 story house and it is fed with RB8.
Cushcraft Laird AR270 Vertical Antenna

[perrybucsdad]

Thanks Doc and Mark.... Mark... that's a small antenna... how do you ground it then... same as was mentioned by above posters by attaching it to a piece of metal or do you have a tripod style mount?

[perrybucsdad]

So it looks like I want to something similar to this...

[n9mxq]

Originally Posted by perrybucsdad

Thanks Doc and Mark.... Mark... that's a small antenna... how do you ground it then... same as was mentioned by above posters by attaching it to a piece of metal or do you have a tripod style mount?

If you put a tripod up, then about 6-8 foot of mast, then the AR270 it should perform well.

I own one of these nice little antennas myself and have never been disappointed with it.

[KS4VT]

Originally Posted by perrybucsdad

Thanks Doc and Mark.... Mark... that's a small antenna... how do you ground it then... same as was mentioned by above posters by attaching it to a piece of metal or do you have a tripod style mount?

Ground?? It is inside an attic. Now if you mean a counterpoise, it doesn't require one.
Actually in my attic I have 2 dual banders and an HF multi-band. That uses a steel counterpoise of the frame that holds the drywall.

As far as an attachment, I use a few piecies of steel bent into an "L" and it is attached to one of the wooden uprights with hose clamps.
It isn't pretty, but it works.

[LtDoc]

I don't think I would waste any 'good' worry about grounding an indoor antenna. Most antennas, as pictured, are complete in themselves, they don't require grounding for RF purposes.
- 'Doc

(If you just 'gotta' ground an indoor antenna, one way of doing it is to just run a wire from the outer 'sleeve' of the coax connector at the antenna's feed point into a bucket of dirt set under the antenna. Nice rich loamy dirt, moderately damp, works best. If you drop that bucket through the ceiling that's YOUR fault, not mine!)
don't believe everything you read...

[n9mxq]

Originally Posted by LtDoc

(If you just 'gotta' ground an indoor antenna, one way of doing it is to just run a wire from the outer 'sleeve' of the coax connector at the antenna's feed point into a bucket of dirt set under the antenna. Nice rich loamy dirt, moderately damp, works best. If you drop that bucket through the ceiling that's YOUR fault, not mine!)
don't believe everything you read...

I've actually seen someone do this.. Ran a ground wire from an antenna to a flower box...

[perrybucsdad]

I'm not sure if you guys are yanking my crank about the bucket of dirt or not, but wouldn't the tripod work as the counterpoise?