. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. TRANSMISSION LINES FOR RADIO SYSTEMS 435 If n is even and the termination is a short circuit or if n is odd and the termination is an open circuit, (12) is employed. If n is odd and the termination is a short circuit or if n is even and the termination is an open circuit, (13) is employed. The attenuation factor is given by: a = - ^ + 77 GZo napiers per foot, = ( y- + GZo ] decibels per foot, (14) (14a) where: R = resistance in ohms per foot, G = conductance in oh
. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. TRANSMISSION LINES FOR RADIO SYSTEMS 435 If n is even and the termination is a short circuit or if n is odd and the termination is an open circuit, (12) is employed. If n is odd and the termination is a short circuit or if n is even and the termination is an open circuit, (13) is employed. The attenuation factor is given by: a = - ^ + 77 GZo napiers per foot, = ( y- + GZo ] decibels per foot, (14) (14a) where: R = resistance in ohms per foot, G = conductance in ohms per foot, and Zq = characteristic impedance in ohms. For all the lines concerned with here tanh [a:(//X/4)3 may be replaced by [q:(//X/4)] without more than per cent error. Thus, (12) and (13) reduce to Zi = 8Zo = R wX 2 4 2Zo' 1 + n\ R GZl R GZl R (12a) (13a) BALANCING CONDENSER ^^ BEATING OSC (PUSH PULL). 300 KG INT FREQ AMPL AND LF DET ATTENUATOR w LOCAL SIGNAL OSC Fig. 16—Schematic diagram of apparatus for measuring line loss by means of a resistance substitution method. Therefore, except for the small contribution of shunt conductance, Zi is independent of Zq. In cases where G is negligible, the measure- ment of Zi gives directly the high-frequency resistance. The method of measurement is shown schematically in Fig. 16 and an experimental set-up appears in Fig. 17. The modified high-fre- 1^ It is assumed here that the conductance term in (14) is small compared with the resistance Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original American Telephone and Telegraph Company. [Short Hills, N. J. , etc. , American Telephone and Telegraph Co. ]
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