January 1946, Electronics - Radar Countermeasures

This article published in 'ELECTRONICS' is placed here to recognize the excellent work done by the pioneers of electronic warfare.
Sir Winston Churchill described WWII as the "wizard's war". In the United States the wizards are the members of the 'Association of Old Crows' and in England the 'Ravens'.

Camp Evans was the home of the U.S. Army's first
electronic countermeasures group.

Contents of this article for quick reference:

Page 92:
   Photo 1 - Wurzburg anti-aircraft radar
   Search and Jamming Functions
Page 93:
   Photo 2 - Chaff and rope being dumped
   Photo 3 - Chaff close-up
   Photo 4 - Effect of chaff on Wurzburg
Page 94:
   Chart 1 - Equipment for Radar Countermeasures
   Photo 5 - Effect of electronic Jamming on scope
Page 95:
   Photo 6 - Effect of jamming on PPI
   Search Techniques
   Wideband Radiators
   Photo 7 - Search and jamming equipment on Navy rcm plane
Page 96:
   Chaff Dipoles and Rope
   Photo 8 - Oscillator of APT-9 jamming transmitter
Page 97:
   Photo 9 - Typical wideband antenna structure
   Tuba and the Resnatron
   Photo 10 - Radiator of the tuba jammer
   Photo 11 - Antenna of German Lichtenstein airborne radar

Infoage says thanks to the Fort Monmouth - AOC
for the donations of funds and EW items for our archives and library.

ELECTRONICS
January 1946

By McGraw-Hill Staff
Page 92 - 97

The Army's first radar countermeasures laboratory
was in the attic of the Marconi Hotel (above)

Equipment for detecting enemy radars, determining their location, analyzing their charac-
teristics and then jamming them electronically or by means of chaff is described. Many of
the devices used, such as shf direction-finders, wideband radiators, and the resnatron tube,
have postwar applications

IN THE RADAR WARFARE just concluded there were two major campaigns. The first was to use radar against the enemy; the second to hinder the enemy in his use of radar against our forces. The second campaign was conducted by techniques known as radar counter-measures, (rcm) by which enemy radars were detected and put out of action.
In many ways rcm activity was the most fascinating aspect of the electronic war, since it involved direct contact with the enemy and required all the competitive strategy and inspiration of a campaign in the field. Technically, also, rcm commands attention, not only be-

cause the methods used were unique and different from those of radar, but also because many rcm devices have post-war uses which may outrank those of radar.
Radar countermeasures were developed and employed by the British in the early stages of the war. Prior to America's entry, rcm activity was also carried out in our own Army and Navy Laboratories, on a long-range basis. The need for coordinated activity led in 1942 to the formation, under Division 15 of the National Defense Research Committee, of an rcm laboratory at Harvard University. This laboratory was known as the Radio Research Laboratory. Of the $300,-

000,000 spent by the U. S. on rcm equipment and materials, approximately two-thirds was for equipment developed in this NDRC activity. The remainder was spent developing methods originating with the British, and in the Naval Research Laboratory, Signal Corps, and Air Technical Service Command Laboratories.

Search and Jamming Functions

To knock out enemy radars, two basic functions are involved. The first is a search, conducted with receivers and direction finders, to determine where the enemy radar is located and as many as possible of its technical characteristics. The second is jamming, accomplished by means of aluminum-foil chaff or rope sowed in the sky by airplanes or by rockets fired from the ground and/or the transmission of signals which will interfere with the operation of the enemy equipment. In the initial stages of the program the two functions were separate. The search was conducted to obtain technical specifications and these specifications were sent home for use in the design of a suitable jammer. The jammer was then produced, on the fastest possible basis, and put into action.

The principal targets of Allied counter. measures in Europe were Wurzburq anti-aircraft radars such as this unit. The Germans had 4000, representing a billion-dollar investment. Jamming reduced their effectiveness to 25 percent of normal

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ELECTRONICS January 1946

ELECTRONICS
January 1946