The idea of a "radio fence" was implicit in this suggestion; i.e., the creation of a long chain of overlapping antenna patterns that the satellite must intersect frequently.
But the Vanguard program could not financially support a long chain of paired stations; besides, further thought soon showed that complete orbital data could be computed from angular (interferometric) tracking alone.
The situation was particularly acute in South American countries that were sensitive about U.S. bases and where transportation and communication facilities were primitive.
Unfortunately, Minitrack stations required radio-quiet spots which are usually not coexistent with the also-desired communication links and supply facilities.
[...] The Site Selection Team had picked six South American locations: Havana, Panama, Quito, Lima, Antofagasta, and Santiago; but who would undertake the imposing task of setting up stations outside the United States proper?
It should be mentioned here that the South American sites, though near large cities, were generally some distance from modern facilities and their associated radio noise.
The stations downrange from Cape Canaveral were set up in cooperation with Great Britain and operated by the U.S. Navy and Air Force.
After deliberation over tracking requirements, logistics, and support facilities, Antigua and Grand Turk were finally chosen for downrange stations instead of the initially planned Barbuda and Mayaguana.
The full Minitrack network of ten stations was placed in operation during October 1957, with the eleventh, at Woomera, Australia, added a month later.
Although a Minitrack station could measure the angles to the satellites very accurately, using this information to determine an orbit required additional work.
Army radio engineers and many amateurs spent the night of 4 October 1957 building and modifying their equipment for Doppler tracking.
Alerted by radio announcements of the Sputnik launching, they burned the midnight oil cutting 40-MHz dipoles and planning network modifications.