![](https://cdn.myportfolio.com/aff86167-610f-4c02-94bd-13a43f7367a7/b1ae2435-68e3-4725-a691-d3bfb7e1fa67_rw_1200.png?h=de966399675f849d8c1aa6ec7ea46690)
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and another unpublished memorandum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