I'll be using a Novatel GPS-703-GGG pinwheel GNSS antenna (
https://novatel.com/support/previous-generation-products-drop-down/previous-generation-products/gps-703-ggg-antenna) for precision timing applications. I'm planning to mount it to my roof and, as I've never done this before, would appreciate suggestions for achieving best results.
I've attached pictures of the roof I'll be working with. I suppose the first consideration is roof location. The easiest location for me to access is the lowest section of the roof (in image 3). This would also leave the cable to the GNSS receiver the shortest. But, maybe I should be concerned with reflections off the higher roof segments at this location. Another possible location would be the lower left corner in image 2. That's a bit further from the window (i.e., longer cable) but should have a slightly clearer sky view. Finally, I could try to mount it near the top for the best sky view, but that would require clambering up the roof, which I'm not eager to do. It's worth noting that the pinwheel antenna should provide pretty good multipath rejection.
Now for mounting. The cinder block method used by sparkfun (
https://learn.sparkfun.com/tutorials/how-to-build-a-diy-gnss-reference-station/all#introduction under "Affix Your Antenna") seems like a good, cheap option. My roof does have a bit of a grade to it - about 13deg at the lower sections (I didn't measure the steeper grade of the upper section). If I need to be worried about the cinder block sliding off, I could drive in some nails downhill of it (other suggestions welcome too!). Another, more expensive option, would be to use something like the Pasternack non-penetrating antenna mount (
https://www.pasternack.com/non-penetrating-antenna-peak-roof-mount-1-pole-version-60-inch-mast-galvanized-steel-with-powder-coating-peprm1-p.aspx). This has a 5ft mast. This would use cinder blocks to weigh down the mount, or drill holes with screws for fastening. How much benefit, if any, would there be in having the antenna mounted further off the roof? Another option, which would require drilling screws into the roof, would be something like this:
https://www.ebay.com/itm/124845460270. That still mounts the antenna closer to the roof but is cheap and I wouldn't need to worry about a cinder block sliding off the roof and crushing someone below or breaking my antenna and pulling my GNSS receiver out of my window... Any special considerations for drilling into a roof?
I'd probably go for the last mounting option (short, screw mount) with the easiest location (3rd picture), unless people recommend I do something else. Thoughts?
In case it's relevant/useful, I'm in Oakland CA. I'd been planning to mount the antenna in the direction normal to the roof, since that's easiest to mount. With the slant, that would have the antenna tilted a bit north (actually about 15deg east of north). But, if it's better to have the antenna facing straight up or potentially even tilted in a different direction, I'd be happy to consider that too.
The novatel antenna has a 5/8"x11 thread.