[time-nuts] Antennas, roofs

[Stan W1LE]

Hello Hal,

You can find roof penetrations in the plumbing dept of Home Depot or Lowes.
Some will handle from a 4" (ID) PVC pipe used as a drain vent, down to a 
1" trade size pipe.

I prefer the rubber gland on sheet metal, vs. the rubber gland on plastic.

Using the white DWV (drain waste vent) PVC pipe will work but is a 
bright white eyesore.
Conside the toned down, grey electrical conduit, also schedule 40.
Galvi pipe works too.

These glands are common to a residential roofer.
Talk to multiple roofing contractors and get their ideas.

My plan is to have the GPS antenna on a metal mast (pipe) slightly 
higher than the ridge line,
penetrating the roof about 1-2' below the ridge line. I will secure the 
metal mast to the rafter inside
 and run the coaxial cable thru the mast to the antenna which screws 
onto the top of the mast.
I will use standard roofing shingles, non metal.

A metal roof will allow reflections off of the roof into the antenna.
Keep the antenna above the highest point of the roof.
But, a standing seam metal roof will allow a cost effective way to 
secure PV solar panels.

Model GPS system performance at the exact location with a temporary antenna
before any permanent holes are made.

Right now I am using a cheap active patch antenna ,  ~ 5$ on ebay,  
outside on a temporary tripod
at gutter height. Lady Heather shows me with 8 satellites, usually under 
reception.

Try the various inside locations for a GPS antenna.
If you can live with the results, avoid the leak potential of a hole in 
the roof.

Ultimately, find the best location with a temporary antenna. make the 
roof penetration, then add a
HP multicoupler inside and feed other GPS receivers. All from a single 
antenna

Your RF electromagnetic environment may be unique. Test at temporary 
locations.
Hopefully, from the final location you can see clean sky from horizon to 
horizon.

I like the radomed (bubble) on the roof, inside installation.
Only gotcha is the non standard product and you would have to engineer it.

Talk to you roofing contractor for ideas, he does this stuph all day long.

What does your Mrs. have to say about the installation ??

Metal roofs are noisey with precipitation, like hale, rain, or snow,
as well as creaky with thermal expansion/contraction.

I would expect a metal roof, properly installed, to last a lifetime,
Can not say that about asphault/fiberglass roofing shingles.

Stan, W1LE    FN41sr    Cape Cod



Hal Murray wrote:
>> I really need to put in a feed through to the roof because my Z3801A
>> is struggling with an indoor antenna too; but the roof needs to get
>> replaced first... 
>>     
>
> Speaking of antennas and roofs....
>
> Currently, my antennas are inside.  That's good enough most of the time.  
> It's also good for providing nasty test cases to software.
>
> I also need a new roof.
>
>
> I'm scheming to poke a hole in the roof so I can get some antennas in a 
> better position.
>
> If I have more than one antenna, does it matter how near eachother they are 
> located?
>
>
> I'm picturing a plastic pipe that sticks up a few feet and a bracket at the 
> base that has the right magic angle to match the pitch of my roof.  The pipe 
> would screw or glue into the bracket.  The bracket would get screwed to the 
> roof over a hole.   The cables would go through the hole and up inside the 
> pipe.
>
> I haven't worked out the details for the top of the pipe yet.  My (handwave) 
> straw man is a U turn to keep the rain out, and mount the antennas on the 
> main pipe.  Maybe a T to get them out to the side.
>
>
> Do brackets like that exist?  If so, what term or brand do I google for?  I 
> have a typical not-very-steep sloped roof.  Is there a standard angle?  ...
>
> Plan B would be to stick the pipe through the roof and attach it inside to 
> the side of a rafter.  I assume the roofers can treat it like a plumbing vent 
> pipe.
>
>
> A slightly crazy idea...  Has anybody poked antennas up inside a skylight?  
> I'm thinking of the setup which has a hole in the ceiling of a room, a box 
> from that hole through the attic space up to and through the roof, and a 
> plastic dome on top.  A shelf or bracket on the inside of the box would get 
> the antennas almost on the outside.
>
>
> I've seen ads for metal roofs/shingles, the claimed advantage being long life 
> which is attractive to me.  I assume they would be a disaster for antennas 
> inside.  What about outside, slightly above the roof?  I'd expect bad things, 
> but maybe there is some way to turn it into an advantage.
>
>
>
>