The Carcinotron was a microwave source that could easily tune its output frequency by changing a single input voltage. This allowed it to jam radar stations by sending out noise on a wide band of frequencies. This images shows the result.
<p>Four jammer aircraft are approaching the station, who's location is the dark spot in the upper left. Two are located at the 4 o'clock position, the other two at 5:30. In those areas, the signal from the carcinotron complete fills the display, rendering the returns from the aircraft, their "blips", invisible. The width of the bright bands is a function of the beamwidth of the antenna, which picks up the signal for several degrees on either side of the aircraft's position.
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Considerable amounts of noise are also visible at most other angles as well. The signal was so strong that it reflections off other objects could also blank out the radar, to some degree. Additionally, the signals also could be seen in the antenna's sidelobes. In this example, one such sidelobe is at the 2:30 position, and shows considerable noise. At closer range, the entire display becomes filled.
unknown RAF photographer
circa 1956 <div style="display: none;">date QS:P,+1956-00-00T00:00:00Z/9,P1480,Q5727902</div>
<a rel="nofollow" class="external free" href="http://www.radarpages.co.uk/download/p172.pdf">http://www.radarpages.co.uk/download/p172.pdf</a>, originally GEC journal