Antennas in the attic

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Antennas in the attic

Edward R Cole
Slightly off topic.

A few years ago my parents built a small home on the farm pond in a
corner parcel of their former farm (which they sold at retirement -
age 77).  One problem was TV reception and they didn't want to
install an outside mast and antenna.  I helped them select a medium
sized VHF/UHF TV antenna (typical modified log-perodic-yagi) and we
searched for a way into the attic.  It was not going to be fun in
tight quarters with fiberglass batting.  Then it occurred to me their
2-1/2 car garage had open rafters.  So I took the antenna with
elements still folded up there and unfolded it pointing toward the
nearest station (about 35mi).  A few years later they ended up with a
DSS dish on the side of the house.

Worked quite well without a preamp (TV booster) even on a couple UHF
stations.  RG6 was used to connect to their TV.

So this suggests that VHF and UHF ham antennas can also work in attics.

73, Ed - KL7UW
http://www.kl7uw.com
[hidden email]
"Kits made by KL7UW"

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Re: Antennas in the attic

Fred Smith
I have use M2 6/2/432 loops on a mobile stack mount in my attic that works
quite well out to 50+ miles. I placed these up there for emergency use in
case of a weather event taking out my outdoor antennas. I have used them
from QRP to 1k on 6m and have preamps for each.

A 160m loop- is a favorite of mine and have one on all bands 6-160m. Do not
have one up at this time but plan on another in the future.

73,
Fred/N0AZZ

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Edward R Cole
Sent: Tuesday, August 13, 2013 11:57 AM
To: [hidden email]
Subject: [Elecraft] Antennas in the attic

Slightly off topic.

A few years ago my parents built a small home on the farm pond in a corner
parcel of their former farm (which they sold at retirement - age 77).  One
problem was TV reception and they didn't want to install an outside mast and
antenna.  I helped them select a medium sized VHF/UHF TV antenna (typical
modified log-perodic-yagi) and we searched for a way into the attic.  It was
not going to be fun in tight quarters with fiberglass batting.  Then it
occurred to me their
2-1/2 car garage had open rafters.  So I took the antenna with elements
still folded up there and unfolded it pointing toward the nearest station
(about 35mi).  A few years later they ended up with a DSS dish on the side
of the house.

Worked quite well without a preamp (TV booster) even on a couple UHF
stations.  RG6 was used to connect to their TV.

So this suggests that VHF and UHF ham antennas can also work in attics.

73, Ed - KL7UW
http://www.kl7uw.com
[hidden email]
"Kits made by KL7UW"

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Re: Antennas in the attic

Phil Kane-2
In reply to this post by Edward R Cole
On 8/13/2013 9:56 AM, Edward R Cole wrote:

> So this suggests that VHF and UHF ham antennas can also work in attics.

For several years I used a 2-m mag-mount antenna upside-down on the
ductwork in the plenum area above my office - 3rd floor of a 6-story
building.  Had no problem reaching repeaters 30+ miles away.  "Radio is
magic" <G>

73 de K2ASP - Phil Kane
Elecraft K2/100   s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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Re: Antennas in the attic

Mike WA8BXN

 

Remember things are different on VHF/UHF bands. Its often FM which reduces
noise problems to some extent, and the wavelengths are shorter and get out
between conductors a lot better than HF.

 

73 - Mike WA8BXN

-------Original Message-------

 

From: Phil Kane

Date: 8/13/2013 2:40:41 PM

To: [hidden email]

Subject: Re: [Elecraft] Antennas in the attic

 

On 8/13/2013 9:56 AM, Edward R Cole wrote:

 

> So this suggests that VHF and UHF ham antennas can also work in attics.

 

For several years I used a 2-m mag-mount antenna upside-down on the

ductwork in the plenum area above my office - 3rd floor of a 6-story

building. Had no problem reaching repeaters 30+ miles away. "Radio is

magic" <G>

 

73 de K2ASP - Phil Kane

Elecraft K2/100 s/n 5402

 

From a Clearing in the Silicon Forest

Beaverton (Washington County) Oregon
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Re: Antennas in the attic

wb4jfi
I've had two meter and UHF antennas in the attic without issues.  I also
have two perpendicular 40M and two perpendicular 20M dipoles in the attic of
my house.  Up to a year ago, all was fine with my K3 running 100W, either
band.  Now, if I transmit as low as 20W on one of the 40M dipoles, it
instantly sets off the fire/smoke detectors in my home security system.
These fire/smoke detectors are probably 15 or more years old, the whole
security system is wired.  Most of the wiring IS in the attic, so no big
surprise.  The 40M dipoles do get our really well, even in the attic.

Since the fire/smoke detectors are being triggered, they set off the whole
alarm, including calling the monitoring service, whether the alarm system is
set (enabled) or not.  The SWR on the primary offending 40M dipole has a
very low SWR, less than 1.2:1 at 7.23MHz.

I'm now researching chokes and bypass caps, and maybe rewiring the smoke
detectors with shielded cables.  The security system hasn't a clue....

So, getting out is not the only issue....
73, Terry, WB4JFI


-----Original Message-----
From: Mike WA8BXN
Sent: Tuesday, August 13, 2013 2:57 PM
To: [hidden email]
Subject: Re: [Elecraft] Antennas in the attic




Remember things are different on VHF/UHF bands. Its often FM which reduces
noise problems to some extent, and the wavelengths are shorter and get out
between conductors a lot better than HF.



73 - Mike WA8BXN

-------Original Message-------



From: Phil Kane

Date: 8/13/2013 2:40:41 PM

To: [hidden email]

Subject: Re: [Elecraft] Antennas in the attic



On 8/13/2013 9:56 AM, Edward R Cole wrote:



> So this suggests that VHF and UHF ham antennas can also work in attics.



For several years I used a 2-m mag-mount antenna upside-down on the

ductwork in the plenum area above my office - 3rd floor of a 6-story

building. Had no problem reaching repeaters 30+ miles away. "Radio is

magic" <G>



73 de K2ASP - Phil Kane

Elecraft K2/100 s/n 5402



From a Clearing in the Silicon Forest

Beaverton (Washington County) Oregon
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Re: Antennas in the attic

Jack Smith-6
In reply to this post by Mike WA8BXN
In years past, part of my work involved signal propagation (VHF/UHF)
predictions and measurements.

For 150 MHz paging service, the generally accepted in-building
attenuation figure was on the order of 10 to 20 dB compared with an
outdoor measurement in the same location. 10 dB or so for typical timber
framed residential construction, 20 dB for reinforced concrete
commercial or multi-unit residential construction, and 30 dB in some
particularly difficult environments with many interior walls and with
high local noise, such as a telephone company switching center.

Almost all the recent literature concentrates on 800 MHz and upward, but
LP. Rice's classic paper from 1959, Radio Transmission into Buildings at
35 and 150 MHz, published in the January 1959 Bell System Technical
Journal still is worthwhile reading. A copy is available at
http://www3.alcatel-lucent.com/bstj/vol38-1959/articles/bstj38-1-197.pdf 
-- however, Rice's study considered only commercial type buildings in
the New York City area.

An attic mounted antenna should exhibit less loss than the roughly 10 dB
figure for residential work at 150 MHz since some allowance for interior
walls is included in the 10 dB figure and an attic antenna only looks
through the roof. Some - perhaps nearly all - of this excess loss will
be offset by the increased height of the attic antenna compared with the
same antenna on a ground or second story floor. As a really rough
estimate, doubling the antenna height above ground level yields 6 dB
increase in signal level. There are lots of caveats in this rule, but if
one is doing back of the envelope estimates it's still a useful concept.
Therefore, I would expect, as a rough and ready estimate an antenna at
12 feet above ground in the attic to work about as well as the same
antenna outside at 5 or 6 feet above ground.

Jack K8ZOA



On 8/13/2013 4:42 PM, Ron D'Eau Claire wrote:

> Keep in mind that absorption by the walls, roof, etc. increases with
> frequency. That's why a microwave oven will heat your dinner but no amount
> of 40 meter signal will do a thing for it.
>
> Still, I've had good success with a J-pole in the attic. No weak signal DX
> work, but a good local signal.
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Mike WA8BXN
> Sent: Tuesday, August 13, 2013 11:58 AM
> To: [hidden email]
> Subject: Re: [Elecraft] Antennas in the attic
>
>
>  
>
> Remember things are different on VHF/UHF bands. Its often FM which reduces
> noise problems to some extent, and the wavelengths are shorter and get out
> between conductors a lot better than HF.
>
>  
>
> 73 - Mike WA8BXN
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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Re: Antennas in the attic

Edward R Cole
In reply to this post by Edward R Cole
OK, OK  My only intent was to suggest that attic antennas are
sometimes surprisingly good and not to forget your VHF/UHF bands as
in typical wood-frame houses work pretty good.

Yes there is absorption by the roof and walls but so it there in a
forest or in the downtown urban concrete "jungle".  Experiment and
you may be surprised.  How hard is it to put a vertical whip up in
the attic?  Well, that depends on access but it is not as involved as
erecting a 100-foot tower with stacked beams for 10, 15 and 20m.

I am lucky because I have nearly 2-acres in the country with no
restrictions.  I can put all the antennas I desire.

My point was we were not sure how well the TV antenna would work - it
did surprising well.  For those of you with restrictions it is an
option to consider.  I would never advise someone to install a
1296-MHz antenna inside (yet some have had success shooting a small
yagi thru a window).

It is well known that absorption increases with frequency so best
results are high and clear with as much gain as you can muster.  If
VHF/UHF = FM, repeaters make up a lot of deficiencies.  But it may
surprise some of you that many hams work CW/SSB on VHF+.

Interaction with home electronics is a risk.  A lot of that depends
on freq. and RF power.

Many years ago (oh no here we go again) I worked as a student
employee at the university's cyclotron lab.  My job was calibrating
the radiation counters.  "Atom Smashers" utilize very high power RF
and, guess what happened?  The RF got into the detectors setting them
off.  That is not a nice thing to do in a high intensity radiation
facility  It was surprising there were no heart attacke over this.  I
learned RFI abatement at a young age.



73, Ed - KL7UW
http://www.kl7uw.com
[hidden email]
"Kits made by KL7UW"

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Re: Antennas in the attic

Eric Swartz - WA6HHQ, Elecraft
Administrator
Folks - We are exceeding the single list posting topic limit for the subjects on
loops and attic antennas. Let's close the threads at this time in the interest
of keeping list noise level under control.

73,

Eric
Elecraft List Moderator
elecraft.com

Eric
elecraft.com
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Re: Antennas in the attic

Terry Schieler-2
In reply to this post by Jack Smith-6
When I built my present (brick and frame) home in 1996 I was fortunate enough to work with my builder and architect and had them design the attic to be void of all HVAC ductwork, AC wiring, low voltage wiring (alarm and telephone) and stereo speaker leads.  The builder thought I was a kook (not entirely wrong).  The builder made me two "catwalks" out from the center of the attic to the far ends so I could get to dipole ends to adjust for resonance ($800 total).  

Today, in my attic, I have:

Alpha Delta-DX-EE (40-20-15-10)
Homebrew WARC fan dipole (30-17-12)
3-ele 6M yagi on rotator
Stacked AEA 6M halos
10M groundplane
2M Msquare "Eggbeater"
70 cm Msquare "Eggbeater"
5-ele 2M yagi (vertically)
2M/440 satellite AZ-EL array
2 DC to daylight "Discones"
Delta loop on and SGC-230 coupler
6M dipole
2M yagi - 2.3 GHz "BBQ Grill" AZ-EL sat antenna array

All compromise antennas, obviously, but they all work and each is "better than a sharp stick in the eye".

73 Terry, WØFM



-----Original Message-----
From: Jack Smith [mailto:[hidden email]]
Sent: Tuesday, August 13, 2013 4:19 PM
To: [hidden email]
Subject: Re: [Elecraft] Antennas in the attic

In years past, part of my work involved signal propagation (VHF/UHF) predictions and measurements.

For 150 MHz paging service, the generally accepted in-building attenuation figure was on the order of 10 to 20 dB compared with an outdoor measurement in the same location. 10 dB or so for typical timber framed residential construction, 20 dB for reinforced concrete commercial or multi-unit residential construction, and 30 dB in some particularly difficult environments with many interior walls and with high local noise, such as a telephone company switching center.


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Re: Antennas in the attic

Bob-270

A poor antenna has infinite gain over no antenna.

73,
Bob
K2TK  ex KN2TKR (1956) & K2TKR
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