. Some experiments with coupled high-frequency circuits . point at which it has ceased to rise. It is also to be noted thatthe maximum amount of energy capable of being drawn intocircuit III is relatively larger, the greater the sending decrement. 3IO Bulletin of the Bureau of Standards [Vol. 7, No. 2 7. COUPLING AND CURRENT DISTRIBUTION BETWEEN A TUNED ANDAN UNTUNED RECEIVING CIRCUIT In several forms of wireless receiving apparatus the detector iscontained in an untuned circuit coupled to the antenna. Sucha case is represented in Fig. 6. Here, as before, circuit I repre-sents the
. Some experiments with coupled high-frequency circuits . point at which it has ceased to rise. It is also to be noted thatthe maximum amount of energy capable of being drawn intocircuit III is relatively larger, the greater the sending decrement. 3IO Bulletin of the Bureau of Standards [Vol. 7, No. 2 7. COUPLING AND CURRENT DISTRIBUTION BETWEEN A TUNED ANDAN UNTUNED RECEIVING CIRCUIT In several forms of wireless receiving apparatus the detector iscontained in an untuned circuit coupled to the antenna. Sucha case is represented in Fig. 6. Here, as before, circuit I repre-sents the sending station, circuit II the antenna, which in thiscase contains a 32-ohm thermoelement, and circuit III, with itsperikon detector and fixed condenser K, the untuned detectorcircuit. It has been shown in another place that the deflections of agalvanometer attached to a perikon detector are proportional tothe square of the current in a circuit to which it is coupled, for anygiven frequency.^^ It is strictly true, however, only when the. Fig. 6 resistance in the circuit is either larger or very much smaller thanthe inductive reactance of the circuit.^^ Table III and Fig. 7 show the relations between the currentsin circuits II and III for different degrees of coupling for a send-ing decrement It is seen that the current in circuit III risesrapidly up to a certain degree of coupHng, beyond which it fallsslightly as the coupling is increased. Comparing Figs. 5 and 7, itappears that the position of the maximum current in circuit IIIoccurs as would be expected, with a much stronger coupling whencircuit III is untuned, and that the maximum itself is much lessstrongly marked. The curves are given for but one value of send-ing decrement, as it was found that the change in the form of thecurve was but very slight, as the sending decrement was varied. °This Bulletin, 6, p. 530; 1910. Zenneck, Leitfaden der drahUosen Telegraphic, p. 78. Austin Coupled High-Frequency Circuits TABL
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