MYSTERIES OF THE EQUILATERAL TRIANGLE - HIKARI Ltd

80 Applications
Application 2 (Satellite Geodesy). In satellite geodesy (the forerunner to
today’s GPS)[53], an equilateral triangle on the Earth (comprised of stations
at Aberdeen, MD; Chandler, MN; and Greenville, MS) with sides roughly 900
miles long was first used in 1962 to verify the accuracy of the satellite triangulation
concept.
With reference to Figure 3.2, the U.S. Coast and Geodetic Survey used
three specially designed ballistic cameras with associated electronic time synchronization
systems to track the motion of the NASA ECHO I communications
satellite. These three observation stations were tied to the existing
triangulation network for the test. After several months of observations, it
was concluded that this process offered precision comparable to, or better
than, the existing conventional triangulation network. This allowed them to
use this process to strengthen the North American Network which includes
the continental United States and Alaska via Canada as well as the islands of
Antigua and Bermuda.
Application 3 (GPS Antenna). An equilateral triangular receiving antenna
can be used in the Global Positioning System (GPS) [274].
With reference to Figure 3.3, C. Scott has constructed a GPS receiving
antenna based upon an equilateral triangular blade monopole design which
approaches the broadband characteristics of a conical monopole. This in turn
gives very broad resonance and reasonable impedance matching. As the aircraft
receiver is not portable, this antenna is suitable for interfacing and debugging
in the laboratory.
Figure 3.4: “Bat’s Ear” Antenna [106]