The tunnel on Taylor Road, Newcastle, CA, which is the best candidate for a tunnel on a road that may have been part of the old US Route 40.... as it officially ends in Utah now. :)
That tunnel runs ENE to WSW or therabouts... 0.103 km or 544.6 feet.... 62 degrees 49 minutes from south to north.... Seems off axis unless the satellite is way off-axis.... but I had to use a seriously off-axis sat once when I lived in CA.... Had to aim the dish almost due east near the horizon... We just renewed for her for another 3 years... She's happy, I'm happy. Waveguide.... I don't know enough to hazard a guess.... But at a an approx 13 centimeter wavelength, sat sigs can certainly travel down a large tunnel if it enters at a small enough angle of incidence.... AND, maybe that water is helping contain the signal in the "guide". #5.... cool to know. 73, ______________________ Clay Autery, KY5G MONTAC Enterprises (318) 518-1389 On 4/15/2017 6:32 PM, Fred Jensen wrote: > Well, one of the side benefits of this list ... lots of smart and > knowledgeable people. A summary and then it can pass into the archive > ... > > 1. The first of "my" tunnels is in Newcastle CA [between Auburn and > Sacramento on the old US40 and Lincoln Hwy route] and was constructed > sometime around the end of the 19th/beginning of the 20th centuries. > It's not quite 1/4 mile long. There is no visible wire or radiax in > it. The hill it runs thru is full of water and you get leaked on when > driving thru it, even in summer. > > 2. In the early 80's, the company I worked for then had a contract to > rehab the communications for the Bay Area Rapid Transit system. We > used a 300 ohm twinlead with a hollow core about 2 1/2 in in diameter > along the ceiling of the tunnels and underground sections. It was 150 > MHz land mobile stuff and the twinlead was fed from a combiner that > put 5 or 6 transmitters into it [train control, fire, security, etc.] > It worked very well. Aligning the combiners [which actually looked a > bit like a still [:-) ] was a bear in the equipment spaces in the tube > under SF Bay but it worked well. They also wanted 800 MHz simulcast > throughout the service area, a requirement probably still waiting for > a real solution. > > 3. Other than under bridges, in canyons, beside heavily forested > roads, and in the garage, where it's obvious the path to the > satellite(s) is blocked, we don't experience any XM drop outs. She's > going to drop the subscription, it's expensive and my new Honda > Ridgeline has become our travel vehicle, but she's had it since 2013. > > 4. I've wondered if there wasn't some sort of waveguide effect in > tunnels. For BART, one of the many problems we had with simulcast was > that it leaked into the tunnels, even as far as the bottom of the > Transbay tube. I don't know the XM satellite frequencies but I > thought they occupied some spectrum abandoned by the Cellphone industry. > > 5. [Bonus Factoid]: The pine forests of the Southeast US are opaque to > 800 MHz. > > Thanks for all the ideas and peripheral info. > > 73, > > Fred ("Skip") K6DGW > Sparks NV USA > Washoe County DM09dn ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com