Value chain · CLM-1480
In plain terms
A 1981 survey for the US energy department says that a beam steered by a signal from the ground cannot form without that signal. If the signal fails, the antenna's parts fall out of step, the power spreads over half the sky, and what reaches the ground is as weak as a radio signal. The survey takes this to mean the beam could not be aimed anywhere except at the signal.
The claim as recorded
A 1981 survey for the US Department of Energy (DOE/ER-0097) states that with an active retrodirective array the power beam cannot be formed without the pilot: if the pilot fails, the transmitter phases become random, the beam spreads over 2 pi steradians (a hemisphere) and the ground flux density falls to communication signal levels, so the system is fail-safe and the beam cannot be pointed at any target other than the pilot.
Scope and limits
A survey statement with no working. The 2 pi steradians holds for an element that radiates over a half-space; it does not hold for a design that loses phase only between large groups, such as the 1978 design's 108 m2 subarrays, whose spread beam covers about 1/45,000 of 2 pi steradians (CALC-144, CLM-1481). "Communication signal levels" is not given as a number. "Impossible to point the beam at targets other than the pilot" is the survey's own view; it does not cover a false pilot set up elsewhere, which the same page meets with an encrypted pilot signal and a dead-man switch (CLM-1478). The foreword names Peter Glaser, the concept's originator, among the authors (SRC-544 row), so the source is not independent of the concept.
What it assumes
Phase set at each transmitter element from the pilot; the same page describes conjugation at each element against a common phase reference.
Where it comes from
PDF p.35 (printed 26), read at a zoom-4 crop: "An additional major advantage is that the power beam cannot be formed in the absence of the pilot signal - if the pilot fails, the transmitter phases become random, spreading the beam over 2" (the page prints the Greek letter pi) "steradians and reducing the ground flux density to communication signal levels. It is thus a fail-safe system, and it is impossible to point the beam at targets other than the pilot."
Basis: solid angle in steradians
Related records
- Answers question
- QST-013 not published in this release
Cite this
energyaperture.com/c/clm-1480
CLM-1480, Energy Aperture, as of 1981-04.
Connected records
Other published records linked to this one. A list, not a judgement.