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    "label": "Report, OSI - 1/49, Central Intelligence Agency, An Estimate of Swedish Capabilities in Science",
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    "title": "Report, OSI - 1/49, Central Intelligence Agency, An Estimate of Swedish Capabilities in Science",
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    "seq": 44,
    "pageIndex": 0,
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    "ocrText": "SECRET\nYearbook of the Royal Academy of Science (1947) that Bergstrand (State Geodetic\nSurvey) has been measuring long linear distances by means of high-frequency signals.\nb. Tubes\nIn vacuum-tube production Sweden was forced by the war to relieve its de-\npendency on outside sources. Consequently, the tube industry has been developed to\nthe extent that soon it should be able to take care of Sweden's needs for most types,\neven for defense. The tube types are largely US, British, and Dutch, of which excellent\ncopies have been made. No subminiature tubes are yet being produced, although\nSvenska Philips apparently receives small quantities from its Netherlands parent com-\npany. There is no known development of magnetrons or klystrons. There was a\nreport, later denied, that Sweden was purchasing VT-fuzes from Contraves Co., Zurich,\nwith subminiatures produced by Brown, Boveri Co. While the fact of the purchase is\nprobably true, the statement on the production of subminiature tubes by Brown, Boveri\nCo. is believed to be in error. The Philips subminiature tube is 7 mm in diameter and\n3 cm long, and includes types up to and including pentodes. It is stated to withstand\naccelerations up to 20,000 g and compares to type T-2 manufactured by Sylvania. The\ntubes are said to be sold only to Holland and Sweden, and in numbers suitable only\nfor development, which is very likely true. It will be easy to expand production in\nThe Netherlands, however.\nResearch on the traveling-wave tube is being carried on by O. Rydbeck and S.\nTomner at Chalmers and at L. M. Ericsson. This work began in 1946-47 and was sup-\nported by Statens Tekniska Forkningsrad (Swedish Technical Research Council). So\nfar, no very favorable signal-to-noise ratios have been achieved, and it is suspected that\nwork is further along theoretically than experimentally. Nevertheless, a tube for a\nwavelength of 3 cm has been built, with a helix diameter of 3 mm, of 0.3-mm Mo wire,\na length of 30 cm, a beam diameter of 1.4 mm, and an effective beam current of 0.1\nma, but with little or no damping. The gun is of the klystron type. Standard X-band\nwaveguide is used for input and output. A focussing magnetic field is used. A fre-\nquency stabilizer has been constructed and used. The theory (small-signal) has been\ndeveloped and checks with the experimental results. Outputs up to 20 mw were\nachieved and the maximum voltage gain was 1.66. Tubes with heavy losses inserted\nand with separate inner and outer helices are now being constructed. Worthwhile\ndevelopments may be expected in the future.\nC.\nOther Areas of Research\nThe electromagnetic effects of thunderstorms have been studied by H. Norin-\nder. W. Stoffregen has paid particular attention to the localization of individual\natmospherics, using a cathode-ray direction finder (unidirectional) type. With this\ndevice, having an aperiodic response up to 50 kc/sec, storm recordings have been taken\nwithout the need for triangulation.\nIonospheric studies all over the earth's surface are being made by a ship in\ntwo-way radio communication with the Chalmers Radio Institute. It is believed that\nan attempt is being made to map the earth for effectiveness of radio transmission.\nIn the antenna field, Sweden possesses at least one outstanding specialist,\nProfessor E. Hallen, Division of Theoretical Electrical Engineering, Royal Institute of\nTechnology. For many years he has been developing the electromagnetic theory of the\nantenna and formulas for calculation of their impedances in actual cases of finite di-\nmensions. Recently, in Acta Polytechnica, he published a complete table of his im-\npedance formulas. He has developed equivalent lumped circuit for special cases.\nIn the broadcast field, Sweden has developed f-m equipment, particularly\nreceivers. A recent design in the 40-55 Mc/sec band has been described by R. Berglund\n37\nSECRET:"
}