. Practical wireless telegraphy; a complete text book for students of radio communication . i^QO 500 400 fiOO 900 500 600 70Q WAVE LENGTH IN METERSFig. 240—Curves Showing the Effect on the Radiated Wave By Progressive Reduction of the Coupling at the Oscillation Transformer. 182. Tight and Loose Coupling.—The adjustment of the coupling ofan oscillation transformer is important because if the primary and secondaryare closely coupled, oscillations of two frequencies occur in the antenna circuitas shown by the curve A, Fig. 240. If the coupling be reduced- (by drawing the primaryand secondary win
. Practical wireless telegraphy; a complete text book for students of radio communication . i^QO 500 400 fiOO 900 500 600 70Q WAVE LENGTH IN METERSFig. 240—Curves Showing the Effect on the Radiated Wave By Progressive Reduction of the Coupling at the Oscillation Transformer. 182. Tight and Loose Coupling.—The adjustment of the coupling ofan oscillation transformer is important because if the primary and secondaryare closely coupled, oscillations of two frequencies occur in the antenna circuitas shown by the curve A, Fig. 240. If the coupling be reduced- (by drawing the primaryand secondary windings apart) and a second resonance curve obtained, the two frequenciestend to merge into one as shown by curve B, Fig. 240. Further reduction of couplingbrings about the condition shown by curve C in which the energy radiated is confined topractically a single frequency of oscillation. The wave C may be of greater or lesseramplitude than waves A and B, according to Fig. 241—Showing How Loose Coupling Can BeObtained With an Auto Transformer. Fig. 242—Another Method for Obtaining LooseCoupling With an Auto Transformer. A popular opinion seems to exist that the required loose coupling for radiating a pure andsharp wave can only be obtained by use of the inductively coupled oscillation to this belief, however, a pure wave can be obtained by other methods of couplingas well. Take, for example, the auto-transformer shown in Fig. 241. By the use of three 220 PRACTICAL WIRELESS TELEGRAPHY. contact clips, the turns for the aerial circuit can be included between C and D and for theprimary circuit between A and B. With the taps in this position, the mutual inductance is reduced and the coup-ling in radiated wavemay therefore possessa damping factor aslow as that obtainedwith the inductivelycoupled system. If the coupling re-quires still further re-duction, contacts Cand D are moved up-ward and away fromA, B, care bei
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
