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Author Topic: Will an attic antenna work?  (Read 1165 times)

KD2HU

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Will an attic antenna work?
« on: April 27, 2020, 02:45:15 PM »

Just a little background for context: I've been away from the hobby for a long time, and I have no equipment. Plus, I live in a condo/HOA/no-antennas-allowed situation. I have a nice attic where I can put something up, but I don't know if it'll work or not. I’m thinking I can make some type of wire antenna(s) for 20, 15, 10, and 6 meters.

It looks like there's no radiant barrier, at least I see nothing but plywood sheathing from the inside. The water heater is up there, and there are some HVAC ducts, but that's all. The ducts are covered in metallic foil with a wire coil inside to make them round. They're at floor level and the roof peak is seven or eight feet above that.  I don’t know what kind of shingles are on the roof.

I took a portable radio up there and it receives both AM and FM broadcast stations normally. Does this mean anything?

So how can I predict if rf will get in and out of the attic BEFORE I buy a rig?


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W6MK

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Re: Will an attic antenna work?
« Reply #1 on: April 27, 2020, 03:20:13 PM »

It receives both AM and FM broadcast stations normally. Does this mean anything?
So how can I predict if rf will get in and out of the attic BEFORE I buy a rig?

You are doing the right kind of thinking, I think.

Certainly if FM broadcast reception is noticeably worse in the attic than at a similar height outside
that would be an indication of your attic being a more challenging antenna location.

RF might get in and out but not well-enough depending on your operating preferences.

The right kind of thinking, I think, would be to consider a plan B: is there somewhere outside
where you can put up an antenna that would not be noticed by HOA nazis? Or could you use
a very small antenna, like a small loop, which could be used on a porch. Or would an antenna
disguised as a flagpole work. Etc.

Plan C; plan D. This is an adventure!

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K0UA

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Re: Will an attic antenna work?
« Reply #2 on: April 27, 2020, 03:32:47 PM »

I have no doubt, a simple fan dipole in in the peak of your attic will "work".  The next question is how bad is the RFI coming out of your and your neighbors houses and the effect it may have on HF operations.  If you were able to receive several AM weak station up there, there is a good chance it would not be too bad.  BUT of course some kind of stealth antenna outside well nearly always be better than some kind of inside antenna. But you have to do what you have to do.  It sounds like you have already done some of the first investigation and are thinking on the right tracks.
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73  James K0UA

K7JQ

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Re: Will an attic antenna work?
« Reply #3 on: April 27, 2020, 03:53:52 PM »

Unless there's a lot of metal up there to reflect RF, dipoles in an attic will "work". But there is RFI to your condo and others to consider, and you won't find that out until it's up and working. How much power you run will have a lot to do with that. That's on the transmit side.

On the receive side, maybe a bigger problem. I've had six monoband dipoles in my attic since 2002, remotely switched from the shack. At first, they worked pretty well...no ductwork or HVAC in that part of the attic, and a concrete tile roof. The main problem: as the years progressed and technology advanced, the steady proliferation of household and neighbors' electronics...Wi Fi modems, DVR's, plasma and LCD TV's, computer monitors, fancy appliance electronics, newer HVAC circuitry, electronic gadgets, and their related switching power supplies and wall warts...all contributed to an ever increasing hash and noise level. So much so, that they are now practically unusable receive-wise. I now use a ground-mounted screwdriver outside, and that works much better, and keeps me on the air.

73 and stay safe,  Bob K7JQ

Note: before I hit "POST", I read K0UA's comment. Kind of similar.
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NN2X

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Re: Will an attic antenna work?
« Reply #4 on: April 27, 2020, 04:24:23 PM »

If you have the room...Here is a great antenna...

Called, the K4KIO Hex Beam...It is 11ft diameter. https://www.k4kio.com/hex-beam-description/

You can use TV rotor..See if you can support this,,,

Another one, is https://alphaantenna.com/product-category/portable-antennas/

If you are like me, you want a great signal....I owned the K4KIO, worked great...I hope you can fit in the attic...

If you need further help, we can connect via Email ,and phone
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KL7CW

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Re: Will an attic antenna work?
« Reply #5 on: April 27, 2020, 05:10:46 PM »

I have found out that it is almost impossible to predict your odds of success in a situation like yours.  I would construct a single band dipole for 20 meters and suspend it near the peak of your roof.  It ok to bend the ends or zig zag it a bit.  Feed it with coax and hopefully put a choke near the feed point.  I said 20 meters, since often RX RFI is much reduced on this band compared to 160, 80, 40 meters.  I know this is mostly a daytime band at this point in the sunspot cycle, but on this band low power of say 5 to perhaps 50 watts, even with a compromise antenna may still be a viable option.  Often with say 5 to 25 watts, or something like this you will not get into your and your neighbors electronics, but at say 100 or more watts there is an excellent chance you will cause trouble with an antenna only 10 or so feet away.  If this works on 20 meters, you could expand operation to the lower frequency bands. Now for a real radical idea.  I operate portable from various places in the lower 48 states, Europe, and the UK, and almost never operate from houses, or hotels, but take my portable equipment to a park, up a hiking trail, or wherever and with simple antennas and QRP power have a blast with low RX noise. Yes it even works from northern Norway and here in Alaska in the winter, but I know this is not everyone's cup of tea.  Even with the tremendous CW advantage, QRP does just not appeal to most "normal" folks. There are some good low power transceivers such as the KX2 and KX3 from Elecraft which run at least 10 watts and are fantastic for portable and even home operation with or without an outboard 100 watt amplifier.  There are lower cost options similar to these units. Most seasoned ops suggesting buying one of the many good used or new 100 watt transceivers, often for less than or much less than $1000 and turning down the power if TX RFI is a problem. Stealth outdoor antennas, even with very small are often even a better area to investigate.   Good Luck   KL7CW
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W5RG

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Re: Will an attic antenna work?
« Reply #6 on: April 27, 2020, 06:20:32 PM »

What about a Flag pole? I also live in a HOA and I have number 26# wire running from a pine tree  in the back yard across the top of the house to a live oak tree. I have it set up as a inverted L with 165ft of 26ga wire. It is very small and is hard to see from the road and it works fine.. Good luck
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W6MK

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Re: Will an attic antenna work?
« Reply #7 on: April 27, 2020, 06:27:50 PM »

K4KIO Hex Beam...It is 11ft diameter.

Not a normal attic-fit. Diameter is twice 11 ft.
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KL7CW

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Re: Will an attic antenna work?
« Reply #8 on: April 27, 2020, 10:16:18 PM »

I have successfully used stealth antennas made with very small wire (26 ga or smaller ?).  The wind or perhaps birds would take them out probably twice a year, but this was in more gentle climates than we have here in Alaska with wind, and ice, but even here I could just string up a new one when necessary.  I have had attic antennas in the past and some worked better than I thought possible, but were still inferior to a good dipole up at a reasonable height outside. I believe there are several books which deal with stealth antennas, you could do a search.  I think ARRL, RSGB, QRPARCI and even perhaps VK3YE may have something of interest to you.  How about a simple one band dipole in your attic, and invite a local ham to come over and try it out for you with his rig.  With 5 W of CW you will do about as good as 100 watts on SSB if TX RFI is an issue.  Join a local club, and someone may be able to give you some hints or even try out your attic or stealth antenna before you buy a rig.  Rick KL7CW
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WB6BYU

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Re: Will an attic antenna work?
« Reply #9 on: April 28, 2020, 11:52:59 AM »

Is there a local ham who can bring a rig over and check it for you?

I'd string up a simple dipole for 20m and hook it to a rig and see
how well you can hear signals over the noise.

K0UA

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Re: Will an attic antenna work?
« Reply #10 on: April 28, 2020, 03:33:23 PM »

I think these ideas of putting up a simple 20 meter dipole and inviting another ham to bring over a rig are excellent ideas. You will know what to expect at a very low economic impact to you.  You will soon know how bad the RFI FROM the house and TO the house will be, at least on 20 meters. Also you will have the benefit of a more experienced operator to give you an idea of "what can be done".  And once you know that something  can be done and has been done by others, this gives you a leg up on doing it yourself.  The old saw of "what one man can do, another man can do" certainly holds true here. I wish you luck, and if you have anything I can help you with, don't hesitate to contact me.   73  James K0UA
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73  James K0UA

WB4BIN

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Re: Will an attic antenna work?
« Reply #11 on: April 30, 2020, 07:31:10 AM »

I use attic antennas.  I have a 20m dipole, 10m dipole, and a 6m omni antenna in my attic.  I also have a 85' "random" wire up there for the lower bands. All of the mechanicals (water heater, AC, house wiring, etc.) are in the attic, too.  The 20m dipole is my go antenna, and I managed to locate it so that the SWR is actually 1:1 on much of the band.  But, I had to play with the location some, as even moving one of the legs a few feet will cause the SWR to jump way up.  The height is only about 15 feet above ground level. 

They work pretty well for what they are, but they can be frustrating, at times.  I've worked about 160 countries, and have worked all states several times.  A lot of that was back when the solar cycle was nearer the peak, and CW is my primary mode of operation.

So yeah, I think you can do OK with it, but it's tough to compete with the big guys.  ;D
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KL7CW

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Re: Will an attic antenna work?
« Reply #12 on: April 30, 2020, 09:59:01 AM »

About 45 years ago I repaired an SSB transceiver for a friend.  I was renting a house on 40 acres, with plenty of high trees, but due to a busy work schedule, and more interest in skiing and climbing, I did not have any antennas set up.  I wanted to really test the rig out for a few weeks on SSB, so rigged up a 20 meter attic dipole, probably only 15 feet above ground level.  I live NE of Anchorage, Alaska, so nearly all my contacts were with lower 48 stations, over 2000 miles distance.  I made dozens of good SSB contacts, even some long rag chews, and a few real DX QSO's.  100 watts worked, but naturally not like my tower mounted Yagis and Quads.  The solar conditions were much better back then, but as Alaska hams will tell you, your penalty for living in Arctic regions is nearly always much more than some occasional advantage to our semi rare calls.  SSB did work, but I do not think I picked up a microphone again for over 30 years, except when I needed to test another ham's rig.  Back then we did not have noise sources in our houses, and in this case I was at least 1/4 mile from any neighbors.  Good luck and do remember the CW advantage (sorry could not resist this advertisement).            Rick   KL7CW        PS, yes SSB and "digital" folks are real hams too, so welcome to the fraternity   !
   
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K0UA

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Re: Will an attic antenna work?
« Reply #13 on: April 30, 2020, 11:00:17 AM »

I use attic antennas.  I have a 20m dipole, 10m dipole, and a 6m omni antenna in my attic.  I also have a 85' "random" wire up there for the lower bands. All of the mechanicals (water heater, AC, house wiring, etc.) are in the attic, too.  The 20m dipole is my go antenna, and I managed to locate it so that the SWR is actually 1:1 on much of the band.  But, I had to play with the location some, as even moving one of the legs a few feet will cause the SWR to jump way up.  The height is only about 15 feet above ground level. 

They work pretty well for what they are, but they can be frustrating, at times.  I've worked about 160 countries, and have worked all states several times.  A lot of that was back when the solar cycle was nearer the peak, and CW is my primary mode of operation.

So yeah, I think you can do OK with it, but it's tough to compete with the big guys.  ;D

You, and Rick  (KL7CW) bring up good points about CW and digital modes.  Most newcomers want to "talk" on HF, and that is fine, and a lot of fun, but when it comes to "miles per watt" CW and Digital modes are very superior to SSB all else being equal.  Especially when operating on compromised antenna systems.
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73  James K0UA

K9IUQ

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Re: Will an attic antenna work?
« Reply #14 on: April 30, 2020, 04:00:50 PM »

But there is RFI to your condo and others to consider, and you won't find that out until it's up and working. How much power you run will have a lot to do with that. That's on the transmit side.

73 and stay safe,  Bob K7JQ

In another life when I was young and between wives I was forced to live in a modern 2 story apartment building. I forget how many apartments there were in a building, maybe 32 or so. Being a Ham, I of course got a second floor (top floor) apartment. I used one of my bedrooms for the radio shack. I duct taped wire around the ceiling making a loop but did not connect the ends and fed it with 300 ohm TV line. At the time I was using mostly SSB and once in a while CW mode. For the first couple months it was great, I made LOTS of Q's, many DX and mostly on 20/15 mtrs. I used a Yaesu FTDX-400 xmtr, about 500 watts (input) or so. QRP was not yet in my vocabulary.

Since I was between wives I was living alone. Imagine my surprise one day when a Telephone Repair Guy knocked on my door and asked if I was having trouble with my Telephone. Being a quick thinker I said Yeah, some damn CBer keeps getting into my telephone conversations. The Telephone guy nodded and said yeah, lots of other people are having the same thing.

After that I never operated the ham gear without first checking the parking lot for a Telephone Truck. I don't think they ever caught that Damn Cber...  ;)

Also when I first took my (unknown to me) next wife into my radio shack to show off my apartment, she said what is with all these radios and the wire on the ceiling, are you with the FBI or CIA or are you just weird?

Most eHamers know the answer to that question.... So yeah, if all you can do is a attic antenna go for it, just be aware of those Damn CBers.   ;) :) :) :)

Stan K9IUQ
« Last Edit: April 30, 2020, 04:07:43 PM by K9IUQ »
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