. An elementary manual of radiotelegraphy and radiotelephony for students and operators . e isno variation in potential at the centre of the Hertzian oscillator orat the earthed end of the Marconi antenna, and this point istherefore called a node of potential. At the free ends or upperend the variations of potential are a maximum, and these pointsare therefore called loops or antinodes of potential. The variations of potential increase fromthe centre or lower end tothe free or upper end, andin the case of the Hertzianoscillator the charges atthe two free ends are alwaysopposite signs. Hence, w
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . e isno variation in potential at the centre of the Hertzian oscillator orat the earthed end of the Marconi antenna, and this point istherefore called a node of potential. At the free ends or upperend the variations of potential are a maximum, and these pointsare therefore called loops or antinodes of potential. The variations of potential increase fromthe centre or lower end tothe free or upper end, andin the case of the Hertzianoscillator the charges atthe two free ends are alwaysopposite signs. Hence, wemay represent these varia-tions of potential by thedistance of a dotted curvefrom a thicker line repre-senting the oscillator orantenna (see Fig. 16 (a)).At the same time there arevariations in the conductioncurrent in different parts ofthe oscillator or antenna which may be represented in the sameway by a fine, firm line. At the centre of the Hertzian oscillatoror the earthed end of the Marconi antenna the amplitude of thecurrent is a maximum, and that point is called an antinode or. RADIATING AND RECEIVING CIRCUITS 171 loop of curront. On tlie other hnud, at the free end, the a)iuIuctioncun-ent is zero, and thtivfoiv these points are nodes of current,Tlie cunenl thti-efore increases j^nidually from the node to thenntinode, and is not the same at iill jioints on the antenna. Itsamplitude at any point may thus he represented by the distanceof a tine, (inn line Iroju a thick line representing the oscillator,as in the diagrams in Fi {a). Again, we may set up oscillations in an open or closed circuit,which are calUd harmonics of the fundamental. For example, inthe case of the earthed Marconi antenna, wo may set up a firstharmonic oscillation in which in addition to the node of ]»otenlialat the eartheil end, there is another, node of potential at aboutone-third of the length of the rod from the open end, and a nodeof current at about one-third of the len^th of the rod from theear
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
