On Wed, 23 Sep 2009 11:45:31 -0700 (PDT), KD7HB
wrote:

So, try running a wire from the phone base unit to the outside of your
house. Experiment with length and placement to see if you get improved
distance. My electronic bell runs in the 300 MHz range, but may well
work for your unit, as well.

Any wire that is excited at a wavelength where the wire is
significantly longer than one wavelength, then this wire stands the
high chance of turning into an end fire antenna. This means if that
wire goes up, so will the signal - straight up (with any number of
very minor lobes in all other directions).

73's
Richard Clark, KB7QHC

On Sep 24, 10:37*am, Richard Clark wrote:
On Wed, 23 Sep 2009 11:45:31 -0700 (PDT), KD7HB
wrote:

So, try running a wire from the phone base unit to the outside of your
house. Experiment with length and placement to see if you get improved
distance. *My electronic bell runs in the 300 MHz range, but may well
work for your unit, as well.

Any wire that is excited at a wavelength where the wire is
significantly longer than one wavelength, then this wire stands the
high chance of turning into an end fire antenna. *This means if that
wire goes up, so will the signal - straight up (with any number of
very minor lobes in all other directions).

73's
Richard Clark, KB7QHC

Hi, Richard.
I learned of this trick many years ago, 1960's time frame. Portland
drilled a second tunnel through a ridge on West Burnside street,
making it two lanes each direction. Drivers began complaining that
their radio reception always went out when they entered the tunnel.
Duh!!! Everyone said nothing could be done, This was the way radio
worked.

One engineer said he could fix it. They mounted insulators in the
tunnel ceiling, and strung a wire the full length of the tunnel. On
the East side, they ran the wire up somewhere on the hillside. I never
was able to determine just where it went. The antenna picked up the
local am/fm signals and radiated them in the tunnel. Drivers could
continue to listen to the radio when they went into the tunnel. Volume
was reduced sometimes, but reception continued.

I wonder if hf and vhf ham radio operation is possible in the tunnel?

I see the same wire trick in other tunnels. The I-90 tunnels East of
Seattle have the wire.

Paul, KD7HB

On Thu, 24 Sep 2009 10:57:19 -0700 (PDT), KD7HB
wrote:

Hi, Richard.
I learned of this trick many years ago, 1960's time frame. Portland
drilled a second tunnel through a ridge on West Burnside street,
making it two lanes each direction. Drivers began complaining that
their radio reception always went out when they entered the tunnel.
Duh!!! Everyone said nothing could be done, This was the way radio
worked.

One engineer said he could fix it. They mounted insulators in the
tunnel ceiling, and strung a wire the full length of the tunnel. On
the East side, they ran the wire up somewhere on the hillside. I never
was able to determine just where it went. The antenna picked up the
local am/fm signals and radiated them in the tunnel. Drivers could
continue to listen to the radio when they went into the tunnel. Volume
was reduced sometimes, but reception continued.

I wonder if hf and vhf ham radio operation is possible in the tunnel?

I see the same wire trick in other tunnels. The I-90 tunnels East of
Seattle have the wire.

Paul, KD7HB

Hi Paul,

You can get the same thing going through the tunnel north of the
Golden Gate bridge (this from my experience of 50 years ago).

What these couplings are, for AM at least, are evanescent waves, what
current science calls Plasmons. Others here cut and paste reports of
Tunneling (of the relativistic kind, not the hole in a mountain kind)
- all the same thing, none of which is understood by those who simply
push the copy button on a Xerox.

As the frequency rises, however, it is harder to propagate that energy
90 degrees off the wire unless you are within one quarter to one third
of a wavelength away (which now brings rise to parasitic coupling - as
I said all of this is the same stuff).

73's
Richard Clark, KB7QHC

Hi Paul

More for interest rather than on topic.

I use to work for the company that did a tunnel rebroadcast systems for
a series of motorway tunnels in Sydney (Australia) back about 5 years ago.

It had to cover a number of operating freqs, mainly AM, FM, cell phones
and certain VHF/UHF comms. Most were active rebroadcast and effectively
were same frequency linear repeaters. The tunnel helped not letting
radiation out as well. Reradiating was done with two cables the length
of the tunnel. AM was a single wire and the rest was via leaky coax. The
single wire was resistive terminated at one end and coupled with some
large toroidal transformer at the source end. I dont remember all the
details but think that the toried had multiple inputs.

We also had a class A amplifier system on a UHF freqency. (about 401MHz
from memory) It had two yagis spaced maybe 20ft apart facing opposite
directions in the tunnel. Enough isolation was achieved to not cause
feedback and of course we had a second pair of yagis stacked above that
for the other direction.

You even find "mine comms" systems that work in a similar vein.

Interesting story about the Portland & Seatle systems, thanks!

Cheers Bob VK2YQA

KD7HB wrote:


I see the same wire trick in other tunnels. The I-90 tunnels East of
Seattle have the wire.

Paul, KD7HB