. La télégraphie sans fil pratique; un livre de texte complet pour les étudiants en communication radio . 6 a 700 ONDES LENGTHFig. 218—courbe de résonance des oscillations de l'antenne. 198 TÉLÉGRAPHIE SANS FIL PRATIQUE. Les points de coordonnées sont disposés sur du papier en coupe transversale à travers lequel une ligne ou un curveis commun est tracé. Voici un ensemble de valeurs type : Longueur d'onde de l'éwavemeter 450 495 525 535 540 560 575 585 600 615 625 635 655 700 déflectiondu wattmètre à fil chaud 0.0 0.005 0.01 0.009 0.01 0.03 0.05 0.08 0.1 0.085 0.05 0.03 0.01 0.00 avec le papier de section transversale devant nous, la longueur d'onde rea
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. Practical wireless telegraphy; a complete text book for students of radio communication . 6oa 700 WAVE LENGTHFig. 218—Resonance Curve of the Antenna Oscillations. 198 PRACTICAL WIRELESS TELEGRAPHY. co-ordinate points are laid off on cross-section paper through which a common line or curveis drawn. A typical set of readings follows: Wave-length of thewavemeter 450 495 525 535 540 560 575 585 600 615 625 635 655 700 Corresponding deflectionof the hot wire wattmeter 0.0 0.005 0.01 0.009 0.01 0.03 0.05 0.08 0.1 0.085 0.05 0.03 0.01 0.00 With the cross-section paper before us, the wave-length readings are laid off horizontallyas indicated in Fig. 218 and are known as the abscissas of the points on the curve, while thehot wire wattmeter readings are laid off vertically and are known as the ordinates of thepoints on the curve. Take, for example, the wave-length of 575 meters; the corresponding. 500 600 WAVE LEN&TH IN METERS 700 60O Fig. 219—Curves Showing the Cliange in Wave Length by Addition of Inductance in a Radio-Freauencv Circuit. PRACTICAL RADIO MEASUREMENTS 199 hot wire wattmeter deflection is .05. Then follow the vertical line corresponding to 575until the horizontal line is met corresponding to .05 and place a dot or a cross. Proceedsimilarly with the entire set of calibrations until all points on the curve are located. Thendraw a line joining them. Now, if the coil, L, of the wavemeter remains in the same position relative to the coil, L-1, and the primary and secondary windings of the oscillation transformer, are set at variouscouplings, the curve in Fig. 218 will become sharper or broader, accordingly, as thecoupling is decreased or increased. By means of these curves the relative sharpness of theradiated waves can be compared allowing to some extent a predetermination of the amountof interference to be expected. If the coupling at the oscillation transform
