Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: ANTENNAS AND THE ATTIC  (Read 921 times)
AJ4RW
Member

Posts: 568




Ignore
« on: August 09, 2009, 05:47:03 AM »

I'm contemplating putting a small beam (MA5B) antenna and rotor in my attic.  I have enough room due to a large attic.  I have a deed restriction that a lawyer is dealing with but as an alternative, I'm exploring the idea.  My roof is of asphalt shingle design on top of OSB board.  There is a small metal vent at the top of the roof and no other major metal objects surrounding.  There are no major electrical fixtures or wiring nearby.  The attic has a high vaulted ceiling and the antenna would be approximately 16' above the ground.  Will the signal degradation from pentrating the material be enough of a concern that the idea won't be feasible?  Also is their any other considerations to be concerned with?  All ideas and comments appreciated.
Tnx & 73 de Randy AJ4RW
Logged
NC2F
Member

Posts: 10




Ignore
« Reply #1 on: August 09, 2009, 06:13:56 AM »

Randy, You can certainly put this to the test as many hams successfully work with antennas in a attic and laying on their roof. Inside you will want to be careful about RF getting into your house AC lines. How much power will you be running?
Logged
KB9CRY
Member

Posts: 4284


WWW

Ignore
« Reply #2 on: August 09, 2009, 06:15:50 AM »

That should work.  Not the best but should work.
Logged
WB5JEO
Member

Posts: 805




Ignore
« Reply #3 on: August 09, 2009, 06:23:31 AM »

The only real complaints have had to do with deterioration of some parts, but that's not going to be an issue in the attic. Now, the construction materials surrounding it aren't entirely non-conductive and will have some effect. I might expect you to have to fiddle a bit more than usual to make any adjustments. Nothing very different about attic mounting this one as opposed to most other antennas. Really, you're fortunate that, with the restrictions, you have enough attic to do something like this. Attic installations are all different, because the environment is unpredictable, but in your situation, it's worth a try. Users have been complimentary on the performance, adjusting for the normal expectations for miniature beams.
Logged
N2RRA
Member

Posts: 646


WWW

Ignore
« Reply #4 on: August 09, 2009, 07:16:25 AM »

So many options for attic antennas!

Steppir IR 2el. if the budget fits. Many advantages over most other yagi, but may not fit the space so here's the other alternative.

Best option! but little pricey would be either a pair of Scorpian screwdiver antennas or Tarheel screw drivers as a rotatable dipole. You'll gain 80-6 meters, have plenty room for rotation and directivity. Motorized tune for best SWR and resonance. Eliminates the tuner or can still use in conjunction if needed.

Mosley makes a mini 32,33, 33WARC! They are the smallest and lightest of all the other triband or multiband yagis and only have a turning radius of about 8 ft. and weighs about 8-12 lbs depending on model.
I think the mosley would be better than the TGM, MA5B, MFJ or others alike.

All though lets not leave out an attic loop. In most cases you can install either a 40 meter dipole fed with ladder, or a loop fed with ladder to tuner with 4:1 at the bench. Try installing as much wire surrounding the perimeter of the attic. If it's a pitched roof try wireing the shape of the entire roof and feed from the center down by the lower perimeter closets to the shack. Works great!

In most cases you can install a Fan Dipole for 40 and 20 meters. By doing this you also get the higher bands with tuner. If you can stretch enough for 80 meters you have good performance all across 80-10, but installing 120-130 ft. of wire in attic might be difficult but possible. If you really get down into the far edges and corner's of the attic looping the ends back it will work depending on what you have in the attic that's metallic of course.

IMPORTANT!

Install at your own risk! Keep in mind you should run only 100 watts or less due to high voltages coming off the ends of any antenna. Anything more than 100 watts make sure you insulate, or keep enough distance from wood rafters and antenna from touching, or arching should accur.

Good Luck with the legal action and deciding which route you want to go.

73's,
Logged
N2RRA
Member

Posts: 646


WWW

Ignore
« Reply #5 on: August 09, 2009, 07:32:13 AM »

Your signal in realation to height above ground you mentioned the roof to reach about 16ft.

Don't expect great results from any antenna no matter what you put in the attic. Even if you mounted it 16ft. outside don't expect a whole lot. The only antenna that can work exceptionally well at 16ft. off ground would be a Cubical Quad. I'm not saying that it won't work, but typical F/B and forward gain will be reduced quite a bit for most antennas at this height. It will all though still allow you to enjoy the amateur bands.

Sounds like to me that your attic doesn't seem to have much metal in it like duct work or a whole lot of electrical lines so deflection from R.F. and R.F.I. should be at a minimum which is great for you.

Good Luck!
Logged
N1DVJ
Member

Posts: 383




Ignore
« Reply #6 on: August 09, 2009, 07:32:44 AM »

Hey, just do it.

Even a bad antenna is better than no antenna.  Heck, back in 1981 I made contacts with a 15M dipole taped to the ceiling in my bedroom apartment.

Way to many people get hung on the 'it's not right' mode of operation. Even if it works like crap, it's working better than nothing.
Logged
VA7CPC
Member

Posts: 2358




Ignore
« Reply #7 on: August 09, 2009, 08:38:22 AM »

It's certainly worth trying.

I think the reason my attic dipole doesn't work very well is that it's surrounded by metal -- rain gutters, alarm wiring, metal flashing on the peak of the roof.

_Without_ all that stuff, it would work about as well as any other dipole 25' in the air.  

         Charles
Logged
W4VR
Member

Posts: 1190


WWW

Ignore
« Reply #8 on: August 09, 2009, 08:58:34 AM »

The problem with having an antenna in the attic or too close to the roof is that you will get into the electric/phone wiring in the structure.  When you operate your radio make sure you're the only one home.  Also, give consideration to RadHaz potential...do the calculation before you buy your antenna.
Logged
W9OY
Member

Posts: 1292


WWW

Ignore
« Reply #9 on: August 09, 2009, 10:33:18 AM »

You'll spend a lot of money for crappy results

I would go for wire antennas, like dipoles, that are resonant on the bands of interest OR I would put a remote tuner at the feed point of a dipole and tune that.  Your best bet however is some kind of outside antenna

73  W9OY
Logged
AB8BC
Member

Posts: 107




Ignore
« Reply #10 on: August 09, 2009, 02:50:54 PM »

I agree with the above poster.  Just try it!!!  If I spent as much time listening to the 'it's a compromise' crowd, I would have missed hundreds of QSO's.  Reasearch and try it!  You might be surprised!--  73  Kirk  AB8BC
Logged
N1LO
Member

Posts: 1039


WWW

Ignore
« Reply #11 on: August 10, 2009, 12:54:48 PM »

I got started with attic antennas, too.

We're at the very bottom of a solar cycle. You'll have the best results now on CW and PSK where the energy density is highest (power/passband width).

As the new cycle builds you'll have more fun on phone, too.

You can use lots of type 31 ferrite split beads on wiring that's in the attic to help keep rf from propagating through the rest of your house wiring.

I made several RF shunts using 110V, three-pronged male plugs, and plugged them into unused outlets in the attic and elsewhere.

Inside the shell of the plug, solder 3 0.01 uFd, 1000V disc ceramic capacitors;
 1) from neutral to hot blade
 2) from neutral to ground pin
 3) from hot to ground pin

GL,

--...MARK_N1LO...--
Logged
N4LI
Member

Posts: 397




Ignore
« Reply #12 on: August 10, 2009, 01:49:00 PM »

I have done attic antennas in another location.  And, I did well -- DXCC on HF, QRP/DXCC, and VUCC on 6m.  Of course, that was near the top if the Cycle.

Attic antennas are a compromise, but they do work.  Just be careful to keep your antennas clear of combustibles (especially the ends where voltages get high) and don't go crazy with the power.

My only real problem?  I learned THE HARD WAY that my fire alarm was resonant on 40m.  That was an unfortunate incident.

Peter, N4LI
Logged
N5LRZ
Member

Posts: 0




Ignore
« Reply #13 on: August 10, 2009, 02:18:08 PM »

Beam in attic should do much better than a dipole in attic....

On the downside>

You might also insert more RF into the building electrical wires (depending on where you are pointing your little beam at the time)
Logged
WA3SKN
Member

Posts: 5443




Ignore
« Reply #14 on: August 11, 2009, 10:03:55 AM »

An attic antenna is a compromise.
A beam at 16 feet is a compromise.
But there is little reason not to try it and see if it works for you!
If you have RFI issues you can shield and filter, or move the antenna outside.
73s.

-Mike.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!