SORU: aşağıdaki parçaya göre cevaplayınız
It is clear from the passage that many of the world's leading countries ----.
The acronym ‘radar', for radio detection and
ranging, has been credited to the US Navy, which
used it officially towards the end of 1940, but the
concept of radar is somewhat older. Hertz showed
that metals would reflect electromagnetic waves and
Tesla is said to have suggested using this
phenomenon in a radar-like manner in 1899. A few
years later a German, Christian Hulsmeyer,
received patents for a ship's anticollision device.
Also many radio engineers and experimenters
observed that passing aircraft or ships interfered
with their experiments. Although these features are
all suggestive of radar, none was actually radar
unless the term is very loosely defined. In the
1930s, however, several of the major powers
became aware of the military possibilities of radar
and work on it started immediately in the USA,
Britain, France, Germany, Italy, Japan and the
Soviet Union. By the end of World War II, military
radar, and military radio navigation aids too, were
well developed.