Illuminated range scale used on Chain-Home (Low) Radar plan position indicators, c.1940. Science Museum Collection.
from death ray to radar:
on atmospherics
direction finding
thermionic valves field strength measurements
an ionised reflecting
layer
at the height of
and another unpublished memorandum
detect by means of
the energy re-radiated
from a transmitter
on the ground
Daventry Experiment
later:
signature tracking
intercept and dismiss
if not to be found within
the expected register
of voice
