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: Laying an insulated Antenna on a cement tile roof  (Read 18077 times)
K7IPP
Member

Posts: 3




Ignore
« on: December 14, 2013, 02:36:40 PM »

I, too, am restricted by my HOA  Angry.  So, I've thought about laying an insulated antenna over the roof made of cement tile  Huh.  I realize that rain will compromise the operation and don't plan on operating with a wet roof.  I'm in Arizona and see sunshine 360 out of 365 days per year.  I'm also only interested in QRP (20 to 30 watts) digital modes on 40, 20, 15 and 10M.

My attic is way too busy with all of the house wiring strung across the attic and all of the cross braces for the heavy tile roof - so an attic antenna is out.

So, does anyone have some science or known facts that would "AYE" or "NAY" stringing an insulated dipole across the roof and using a balun and coax to feed it to the Transceiver?

Neil, KG7HEA
Logged
K5LXP
Member

Posts: 4479


WWW

Ignore
« Reply #1 on: December 14, 2013, 05:20:16 PM »

This isn't a aye or nay decision.  It's a matter of degree, balanced against your level of expectation.   There isn't much of the "science" of it you can apply here, other than you know there will be some impact to performance vs the same wire in free space.  The variables for your exact installation are unique and impossible to predict.

The only way to know if it will meet your expectations is to put it up and try it. 


Mark K5LXP
Albuquerque, NM
Logged
W1VT
Member

Posts: 825




Ignore
« Reply #2 on: December 16, 2013, 08:21:32 AM »

The scientific approach would be to electrically measure a sample of the roof tile, and then use those measurements to model the antenna in an antenna simulation program--which could calculate the pattern and losses compared to a reference antenna.  But, as Mark points out, this still doesn't tell you whether it will work well enough for you needs.  There are hams that are quite pleased with the few contacts they make with a really lousy antenna--I worked South Dakota on 10M with my flagpole!   Then there are other hams who grouse about not being able to work every DX-pedition they need for a new country.

If it were me, I'd use an aluminum flagpole designed to display the American flag--President Bush and Congress passed a law that limits the rights of HOAs in outlawing such displays. It is likely that they can make you take down the insulated wire on the roof.

Zack W1VT
« Last Edit: December 16, 2013, 08:27:00 AM by W1VT » Logged
WB2WIK
Member

Posts: 20595




Ignore
« Reply #3 on: December 16, 2013, 10:42:29 AM »

There may be different types of "cement tile" for roofs, but in my last home in Chatsworth, we had what the builder called "lightweight cement tile" for the roof.  Thousands of them, and I guess although "lightweight" they still weighed several pounds each.  They had pre-drilled little holes along one edge so they could be nailed into position using exactly those holes (and I found out more about this after our 1994 earthquake, which cracked several of the tiles so they needed replacement).

In my case, the roofing material was a horrible RF dielectric.  Laying a wire on it was about the same as laying the wire on the ground.

Thankfully in my case that didn't really matter, as I did not have restrictions and did have towers and stuff up way behind the house, far away from that roof!  My VHF-UHF vertical omni antennas above that roof worked fine, nothing below them would have any influence.  But when I tried an "expedient" insulated wire antenna up there just for some fun backyard poolside type operation I found out how bad it was for that purpose.

Logged
W6RMK
Member

Posts: 651




Ignore
« Reply #4 on: December 18, 2013, 06:50:30 PM »

I have a multiband dipole laying on my cement tile (Monier LifeTile, but there's a zillion kinds of those). 
1) You'll need a tuner.. there's no way to predict what the Z is, and it changes depending on how wet the roof is, so even if you spent hours running up and down the ladder and pruning, you're still going to be wrong some of the time.
2) It changes performance a LOT when it gets wet.  It's easy to tell when the dew evaporates.

If you can space it a foot or so off the top, it works a LOT better.  Tell people it's to keep the pigeons from roosting on the ridge pole.
Logged
VE3FMC
Member

Posts: 987


WWW

Ignore
« Reply #5 on: December 19, 2013, 04:32:57 PM »

My vote is for a flagpole with some radials buried around it and an auto tuner at the base hidden in a flower bed.
Logged
K1CJS
Member

Posts: 6034




Ignore
« Reply #6 on: December 20, 2013, 07:14:19 AM »

You can go ahead and try it, but for the minerals and the other content of the "cement", you'll probably find it won't work very well.  As 'WIK said, most of those type panels make a horrible dielectric.
Logged
K5TED
Member

Posts: 727




Ignore
« Reply #7 on: January 05, 2014, 09:10:16 PM »

Does the HOA rule prevent putting a mast on either end of the home, centered on the gable, extending only about 9" above the actual roof height, and a mast on each rear corner, also 9" taller than the eave, and suspend a loop or just end fed wire from these mast tops? Would not be visible from the street.

Alternately, don't use the gable masts, and just use the rear corner masts, again, maybe 12" or so taller than the eave, and the wire running to the peak, anchored there, and feed it like a dipole or make one long U shape wire, end fed? Also, not visible from the street.

Not optimal, but better than no antenna.
Logged
KD8IIC
Member

Posts: 157




Ignore
« Reply #8 on: February 04, 2014, 10:05:28 AM »

   Put it up, Play it, Enjoy what it does well, You may be pleasantly surprised! Nothing Ventured, Nothing Gained.  73
Logged
W6FEI
Member

Posts: 9




Ignore
« Reply #9 on: February 07, 2014, 12:53:31 PM »

I have not had very much luck with attic antennas with the cement type roofing. Wood Shingle roofs seem to be much better in that regard. I have had very decent results running a small gauge wire as a G5-RV behind my rain gutters around the house. Of course that works if they are fiberglass as mine are. It still is no replacement for an antenna in the air, but thanks to HOA and CC&R's we need to do what we can to work our hobby. I see that ARRL is still saying they are working on getting legislation passed to help with this, but that may never go anywhere. It would be interesting to know how many thousands of us are being hampered by these rules and how the future Ham generation coming into the fold may be affected or discouraged from pursing it.

W6FEI
Logged
K7IPP
Member

Posts: 3




Ignore
« Reply #10 on: February 07, 2014, 01:53:19 PM »

I want to thank all of you for your inputs.  Kiss

I have not come to a decision yet.  Undecided

I didn't realize that I had so many hobbies that take up so much time and then I added hamming to the mix.  Right now, in Arizona, it is "outdoor" weather and that is what I am doing.  When it gets to be "indoor", in the summer, then I can switch my attention to hamming.

And I will still appreciate any and all comments about this subject that are forthcoming.   Wink

Neil, K7IPP
Logged
WB7RBN
Member

Posts: 14




Ignore
« Reply #11 on: February 16, 2014, 06:04:00 AM »

I live in a townhouse with CC&R antenna restrictions but I am able to get on the air.  The roof is asphalt singles.  I have a delta loop made of thin magnet wire laying on the roof and feed by 300 ohm TV twin lead (the clear stuff).  I ran it from the peak to the each end of the roof and fed it in the center at the bottom.  It is tuned by a Icom AH-4 automatic antenna tuner.  Works 6 through 80 meters just fine.  In fact it works great as a NVIS antenna on 40 and 75 meters. The magnet wire is so thin you can barely see it.  Nobody has ever say a word.

For 2 meter/440 I have a homemade J pole (same 300 ohm twinlead) hanging in the corner of the shack.  I can hit all the local reapeaters plus one 60 miles away using just 10 watts.

Hope this helps.

Jim
Logged
W6RMK
Member

Posts: 651




Ignore
« Reply #12 on: February 16, 2014, 09:26:36 AM »

A strategy I've wanted to try is to string the wire about 6" above the roof, supported on something like pieces of 4" plastic pipe.  It's fairly unobtrusive, and gets the wire away from the wet roof surface.   If you wanted to call it a "pigeon roosting preventive" you might be able to do that, but I think that trying to claim an antenna isn't an antenna is a losing cause in the long run.
Logged
AD1E
Member

Posts: 8




Ignore
« Reply #13 on: February 23, 2014, 02:44:47 PM »

Neil

If you have trees, try a Par End Fedz http://www.universal-radio.com/catalog/hamwire/4456.html

They hide well in trees and need no tuner.
I am in Tempe with a HOA and have a 20 & 40 meter hidden in the tree in the front yard and they work great. 
Logged
KD8NGE
Member

Posts: 36




Ignore
« Reply #14 on: March 08, 2014, 09:14:39 AM »

WB7RBN said it rightly:  magnet wire an an AH-4!
I too had a magnet wire delta, but it was suspended 8 ft above the sod behind the house.  Not a true delta, at one corner I detoured up and over the top fork of a mostly dead snag, back down its back side and horizontal again to finish the delta configuration. 
(A little learning is a dangerous thing, as the wise man said  Roll Eyes  and my thought was to have the advantage of both NVIS and a vertical.  I think it actually worked in spite of my efforts and not because of them, but it worked well enough for my level of inexperience!)
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!