October 1963 Popular Electronics
 Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Popular Electronics,
published October 1954 - April 1985. All copyrights are hereby acknowledged.
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Communications links
are so ubiquitous these days that we pretty much take for granted the ability to
connect to the Internet and to other people. How many times have you been in public
and heard someone have a fit because she couldn't get a good enough signal to make
a call? It requires the person to get up and walk a few feet or maybe turn her chair
in another direction to get an extra bar on the iPhone. How inconvenient. Even when
placing a call to Hawaii or Alaska the expectation is that things just work. In
1963 when this tropospheric scattering network was installed for linking Alaska
to the lower 48 states, satellite communications was still in its infancy and coverage
was nowhere close to global. Even radio relay towers were relatively scarce across
the landscape. We've come a long way, baby.
A Bridge to Alaska
 One
of the first high-capacity commercial tropospheric scatter systems to go into operation
will shortly bridge the icy coastal waters between Annette Island, Alaska, and Vancouver
Island, British Columbia.
Tropospheric scatter relies on the fragmentary refraction of microwaves back
to earth by the troposphere - the turbulent layer of atmosphere extending up to
six miles. This type of radio propagation requires very high power and huge transmitting
antennas which beam a signal just over the horizon so that refraction occurs several
miles above the earth. Highly sensitive receiving equipment is necessary to reconstruct
the transmitted signal.
The tropospheric scatter network has two legs with a central relay as shown by
the map (the link from Port Hardy to Vancouver is conventional microwave). Each
antenna - see photo at right - weighs 70 tons and is built of galvanized steel sheets
to take winds up to 120 m.p.h. As shown in the map above, the Annette-Port Hardy
link required use of a central relay located on Trutch Island. The system includes
two transmitters, four receivers and two antennas - 70-ton, 60-foot-square monsters
- at Annette and Port Hardy, and four transmitters, eight receivers, and four antennas
at Trutch Island.
The $5 million, 344-mile link provides 240 channels for voice communications
and data transmissions. At Vancouver Island, a conventional 275-mile microwave radio
system connects with the city of Vancouver and telephone circuits to the United
States. The installation at tiny, storm-tossed Trutch Island, which is manned on
a 24-hour basis, necessitated the formation of a community with all utilities for
27 people.
The tropospheric network was constructed by General Telephone & Electronics
Corp. and its subsidiaries.
Posted April 19, 2021
(updated from original post on 1/17/2013)
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