Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

206 FREQUENCY MODULATION, Volume IISOLATION METHODS FOR F-M ANTENNASMOUNTED ON A-M TOWERS*!ByRobert F. HoltzEngineering Products Department, RCA Division,Camden, N. J.SummaryThe problem of mounting FM radiators atop AM towers is dealt withfor both shunt-and series-fed AM towers. The general desirability of FMantennas atop AM towers is discussed. No particular problem other thanstructural requirements exists in the case of shunt-fed AM towers. However,in the case of series-fed AM towers, the more-usual arrangement, an isolatorunit is required. Such a unit is described and its function and operationdiscussed in detail.* Decimal Classification : R320,f Broadcast News, October, 1946.(2 pages; 4 figures)SLOT ANTENNAS*fByN. E. LlNDENBLADResearch Department, RCA Laboratories Division,Rocky Point, N. Y.SummaryThe development of flush-type radiators of the slot and pocket type isdescribed. Special emphasis is made of types applicable to aircraft. Specificsolutions to altimeter and marker beacon pickup antennas are described.Reference to application in other fields is also made.The general aspects of the phenomena which are involved are examinedand it becomes evident that workable solutions, in the majority of cases,can be obtained only by means of actual experiment, since variations in thesurroundings have first-order influence upon such vital characteristics asradiation patterns, slot impedance, and bandwidth.Progress before and during the war is described in somewhat chronologicalmanner. It is pointed out that while this progress has been considerable,an appreciable amount of skillful investigation remains to be donebefore slot antennas can be brought to maximum usefulness.(7 pages; 19 figures)Decimal Classification: R326.21 X R630.t Proc. I.R.E., December, 1947.