OTOH, this can be a feature of tunnels, not a bug. Several years ago I was riding on the “BikePike”, an abandoned section of the PA Turnpike east of Breezewood that has become a bicycle route featuring two old tunnels. Although closed off to motor vehicle traffic, we noticed a pickup parked outside the entrance to one of the tunnels. A few hundred yards into the tunnel we encountered a minivan with lots of high end electronic test equipment. Turns out the guys were doing tests on some military equipment, to determine that it was RF quiet to prevent detection by enemy forces. We didn’t ask a lot more, lest they would have had to shoot us :-)
73 - Jim K8MR > On Apr 15, 2017, at 10:43 AM, Phil Hystad <[email protected]> wrote: > > A number of tunnels are “wired” for broadband radio reception. A bit of > years ago when they were building the I-90 stretch between Bellevue and > Seattle there are two major “tunnels” on each side of the I-90 floating > bridge (across Lake Washington). The tunnel on Mercer Island is actually not > a tunnel but a covered section of the freeway but the tunnel on the west end > is through the hill (known as the Mount Baker tunnel but not because it is > under Mount Baker but because it is under the Mount Baker neighborhood of > Seattle). > > So, a news article at the time described how the technology was employed to > provide radio reception for AM, FM, and also cellular communication. I don’t > remember reading about Sirius/XM radio though. I do know that my HF mobile > operations come to a halt through those tunnels. As signals drop off after a > 100 feet or so from the opening and don’t come back until the other side. > > Unfortunately, I can’t remember anything of the details of how this was done > but I suspect wide-band amplifiers and wires and top-side wide-band antennas. > > 73, phil, K7PEH > > >> On Apr 14, 2017, at 8:47 PM, Fred Jensen <[email protected]> wrote: >> >> Semi-related curiosity regarding shielding. My wife's car has Sirius/XM >> radio. It usually loses contact with the satellite driving under Interstate >> bridges and the like. Likewise in the garage. OTOH, at our previous home >> there was a tunnel through a small hill, perhaps 1/4 mi long. The XM worked >> fine through it. There are a pair of tunnels at Cave Rock next to Lake Tahoe >> through a granite mountain. XM works fine through them too. Anyone know >> why? >> >> 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
