My wife has decided that instead of writing a check for a Z-Max, sorry Mike, the money will instead go for a new roof and the removal of some very big trees. Not to make a complete loss of said project, I have convinced her that we should include the venting cupolas that she wants. My intent is to use transmissive peaked roofs on said cupolas so that I can mount GPS antennas under same for a home base station. I am using the plural because until the trees are gone and antennas are mounted I am not sure which peak will afford better reception.

Any body have any experience building their own snow cone or dome? Are any plastics better than others?

I figure that as soon as I have it up and running they will activate the local CORS they have been promising for two years. It is only 8 miles away, so any extra cost for the transmissive roof may be worth getting the CORS on line.

Paul in PA
Modified By Lawrence Paul Lopresti on 7/26/2005 at 11:30 PM

I saved the following information from a scientific discussion forum while searching for information on radomes.


"I have a need to build a radome to house a two GPS antenna.
The question is to do with the best material to use to minimse signal attenuation.

The choices available are different mouldable plastics:

Polycarbonate
Acrylic,
Exterior quality ABS,
High Impact Polystyrene,
Polypropylene.

Are there any documented charateristics for these materials at L1/L2 (1.2 to 1.6 GHz) frequencies?


http://www.asiinstr.com/technical/Dielectric%20Constants.htm

The above site has a large list of materials with their dielectric constant ranges. Polypropylene looks best per your list...dielectric constant is 1.5 to 1.8(very low loss). I would think weathering and impact info would be considerations also in selecting an appropriate material. I hope this helps some."


The web site URL is updated and it should work. It covers a huge range of materials.

Also you may want to review the information on radomes at
the Unavco site-

http://www.unavco.org/facility/project_support/permanent/equipment/radomes/radomes.html

that may be the wrong answers. I figure Paul is only wanting to know who would use Tupperware and who would chose brand "X"

I would take the T-ware

Thanks L.A.

The intent is to construct a pyramid, white in color, such that antenna can be changed, replaced etc. from within the structure. It will be on the peak of a two story roof in a residential neighborhood. I think it will look better than a plain antenna. It will have lightning protection, not to protect the equipment, but to protect my house. It has to be large enough to allow the antenna ground plane to sit higher than the surrounding wood/metal structure.

I want to be able to establish coordinates with an L1/L2 receiver then use various antennas and receivers as the base. I have some streaming data receivers as well as my survey field equipment. This way I can play at night without running around my backyard.

Paul in PA

Are you intending to access the antennas from inside the house, or having to access from outside the house?

Those copolas can be awfully small to reach up into from below.

I am dissatisfied with my antenna. Even though I weatherproofed the connections, presently my cable is not feeding data and you're idea has appeal.

Is house movement, over time and throughout the day a concern? If so, do you have a way of monitoring the movement or are you going to use an L1/L2 unit, not just to
"establish" the coordinates, but also to "monitor" the position?

I don't understand the idea of being able to exchange antennas, unless you mean in long-term reference.

I think I might go outside and look at my roof and imagine the skyline from that reference.

I expect very little movement of the house. It is solid, I designed my roof trusses myself. My attic area is accessible. I am looking at a 3'x3' box. I will have a tribrach base permanently mounted. I will have separate trbrach adapters for each antenna so that I can adjust the heights for the exact same ARP for any antenna. I will establish my coordinates with my Ashtech?Topcon Big Yellow Whopper. I want to test the Millenium Falcon(Whopper with a skull fracture) and various L1 and L1/Glonass antennas. Then I will do a long term test with DGPS, Coast Guard beacon (I am a long way from three stations, E, S & NW).

I will most likely use my Super CA as a base when I am near home and use a Z-12 & 3 ProMarks for survey work.

Then I have a SirfStar module to test. That is an integrated DGPS in a tiny box streaming data to a computer. I will test it with a small hockey puck antenna and with an antenna from an Ashtech Reliance. I will probably do a long term test with the M-12 to see how tight 24 hours of old style data can be.

While doing my base control I will be out on some local NGS monumunts tying them in. Maybe I can predict where they end up on the readjustment.

The second cupola location is not accessible from the house. It will probably get an L1 or combined L1/Beacon antenna permanently mounted once I have fixed its position. The streaming DGPS data will have static data on the main base to compare it to.

Paul in PA