. The Bell System technical journal . ary in the power pulsers, harmonic components must be built can be done by providing additional resonances in the discharge circuitat the wanted harmonic frequencies. With the close spacing between circuit elements and their proximity tothe pulser box walls, parasitic capacitances of appreciable magnitude addto those normally present. These involve dielectrics of low loss and, sincethe circuit elements and connecting wires are firmly fixed in position, theyare fairly well reproduced. They can be used, therefore, in conjunction 4 The Magnetron as a
. The Bell System technical journal . ary in the power pulsers, harmonic components must be built can be done by providing additional resonances in the discharge circuitat the wanted harmonic frequencies. With the close spacing between circuit elements and their proximity tothe pulser box walls, parasitic capacitances of appreciable magnitude addto those normally present. These involve dielectrics of low loss and, sincethe circuit elements and connecting wires are firmly fixed in position, theyare fairly well reproduced. They can be used, therefore, in conjunction 4 The Magnetron as a Generator of Centimeter Waves, by Fisk, Hagstrum, and Hart-man, , April, 1946. COIL PULSERS FOR RADAR 613 with added reactors of small size to provide harmonic resonances neededto shape the discharge pulse. These help to bring up the third and fifth,and in some cases higher harmonics. Results after shaping are shown in Fig. 4 for two extremes of pulse shorter pulse, roughly a quarter microsecond in average duration,. Fig. 4—Shaped magnetron current i)ulscs, together with the radio lre(iuency si)ectro-grams corresponding. Pulse at u])per left indicates ])resence of high harmonics; pulse atupper right shows strong fifth harmonic and little at higher harmonics. The band widthof the main energy lobe, and the dispersion of energy outside that band in both cases indi-cate negligibly srnall effect attriliutable to fretjuency modulation. evidences the presence of fairly high harmonics. The wider pulse, roughlyone and a quarter microseconds in average duration, has a strong fifthharmonic and some even harmonics as well.^ Below each pulse is shown aspectrogram of the corresponding magnetron high-freqtiency output, which 5 Magnetron currents are shown rather than voltages, since current is a far moresensitive indicator of performance. 614 BELL SYSTEM TECHNICAL JOURNAL represents energy as a function of frequency. Different magnetrons areused with the two pulses; their
Size: 1597px × 1565px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
