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 <k6...@foothill.net> 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
>
> On 4/14/2017 2:50 PM, Phil Kane wrote:
>> On 4/14/2017 1:13 PM, KENT TRIMBLE wrote:
>>
>>> The assumption has always been that the driver and passengers are riding
>>> inside a Faraday Cage and therefore are safe from RF radiated by an HF
>>> antenna, regardless of where located and regardless of power level.
>> When I take my 2011 Ford Focus through the car wash, I put the mag-mount
>> VHF antenna inside the car but it is still connected to the radio. I
>> have no problem picking up the usual 2- and 3/4- meter repeaters that
>> way. So much for the "Faraday Cage". :)
>>
>> 73 de K2ASP - Phil Kane
>> Elecraft K2/100 s/n 5402
>>
>
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