Radio age research, manufacturing, communications, broadcasting, television (1941)

CALCULATES ANTENNA DESIGN 10NG, tedious mathematical com- J putations which have been nec- essary in solving the intricate prob- lems involving the location and arrangement of radio towers may now be replaced by a new electronic device called the Antennalyzer, Dr. George H. Brown of RCA Labora- tories announced recently at a meet- ing of the Washington, D. C, sec- tion of the Institute of Radio Engi- neers. Field tests and calculations, which formerly required weeks to perform, are now done in a matter of minutes by this electronic com- puting machine which adds and subtracts angles, multiplies, looks up trigonometric functions, adds numbers, squares them and finally takes the square root of the whole to produce the desired answer which the engineers must have to accur- ately locate a directional radio an- tenna. The Antennalyzer, a new magic brain in the field of radio, consists of 52 electron tubes. The associate circuits can be adjusted to duplicate all characteristics of a projected an- tenna. In operation, the controls of the machine are regulated until a pattern of light on a cathode ray tube is identical with the desired pattern of transmission of the broadcast station. Final dial read- ings not only tell where to locate the towers, but give all electrical data needed to complete the most efficient antenna design. Publishes New Magazine First issue of a new Spanish Ian- gauge magazine, Radio Mundial, published by the RCA International Division is now being distributed throughout Latin America. The new periodical, a quarterly, is de- signed for Spanish speaking people interested in radio broadcasting, radio communications, television and allied activities. PROBLEMS OF LOCATING AND ARRANGING ANTENNAS CAN BE SOLVED IN A FEW MINUTES BY THIS ELECTRONIC DEVICE. NEW CIRCUIT LOWERS COST OF FM RADIOS ANEW radio circuit for fre- quency modulation (FM) re- ceivers which makes it possible for the first time to build a receiver that realizes the advantages of FM at a cost comparable to that of standard band receivers, was de- scribed by Stuart Wm. Seeley, man- ager of the Industry Service Divi- sion of RCA Laboratories, in a paper delivered to a recent meeting of the Institute of Radio Engineers in New York. FM sets produced before the war, Mr. Seeley pointed out, required the use of one or more tubes whose functions were solely that of noise suppression. They contributed nothing to the volume of the receiv- er output. Furthermore, he said, to make these extra tubes fully ef- fective, considerable amplification of the received signal was neces- sary. Although both of these re- quirements added noticeably to the cost of FM receivers, noise contin- ued to be present when the strength of a received signal fell below a cer- [RADIO AGE 231 tain point called the threshold level. According to Mr. Seeley, the new RCA circuit, called a ratio detector, is insensitive to electrical interfer- ence of all kinds, whether man-made by ignition systems, oil burners and domestic appliances, or natural, such as atmospheric static. Mr. Seeley added that the new circuit is not only free of a critical threshold signal level, operating equally effectively on strong and weak stations, but its incorporation in a receiver eliminates the need for additional tubes and parts that formerly were considered necessary in frequency modulation receivers. It is this simplification, he said, that should reduce the manufacturing cost of FM receivers to a point com- parable with that of receivers cov- ering the standard broadcast bands. The RCA Victor Division has announced that the development would be embodied in future models of RCA receivers. STUART W. SEELEY CONDUCTS TEST ON A RECEIVER CHASSIS EMBODYING A NEW FM RADIO CIRCUIT WHICH REDUCES THE NUMBER OF TUBES REQUIRED.