. Das Bell System technische Journal . des (außer höher-Ordnung kreisförmige elektrische Wellen, TEOM) haben eine charakteristische der allgemeinen Form skizziert für die dominante Welle (zehn) auch shownin Abbildungen. 3 und 4. Die Wandlongitudinalströme tragen zu einem Verlustausgleich bei, der aufgrund der Hautwirkung bei steigenden Frequenzen ansteigt; dies gilt für die positive Steigung der zehn-Kurve auf der rechten Seite von Abb. 3 und 4. Die negative Steigung der TEoi-Kurven und des linken Teils der zehn Kuren in Abb. 3 und 4 ist eine Weihe von Verlusten, die mit den Wandströmen verbunden sind, die die Welle her verhindern
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. The Bell System technical journal . des(except higher-order circular-electric waves, TEom) have a characteristicof the general form sketched for the dominant wave (TEn) also shownin Figs. 3 and 4. The longitudinal wall currents contribute a loss com-ponent which rises at increasing frequencies due to skin effect; this ac-counts for the positive slope of the TEn curve at the right-hand side ofFigs. 3 and 4. The negative slope of the TEoi curves and of the left-handportion of the TEn cures in Figs. 3 and 4 is a consecjuence of lossesassociated with the wall currents which prevent the wave from spread-ing as it would in an unbounded medium; these currents and the lossesassociated with them decrease as the operating fretjuency becomesfarther removed from cut-off. For a loss of 2 db per mile Fig. 3 shows that a waveguide 1 in diam-eter is recjuired in the freciuency band near 4, 000 me where the TI)-2system operates. Whereas this may not Ix pr()hil)itive in a comiectiiig 1216 THE BELL SYSTEM TECHNICAL .TOURXAL, NOVEMBER 1954. FREQUENCY IN MEGACYCLES PER SECOND Fig. 4 — Round guide diameter versus frequency for attenuation of 13.2 db/mile (0.25 db/100 ft.). link application, the waveguide size is definitely too large for long-distance application. In the vicinitj^ of 50, 000 mc, however. Fig. 3 showsthat the reciuired waveguide size is on the order of 2, and this is com-parable to the size of the present standard 8-pipe coaxial cable. Fromthese simple calculations, it is evident that carrier frecjuencies in thevicinity of 50, 000 mc or more are ver}- desirable for long-distance wave-guide applications in order to minimize the size of the waeguide. Other reasons for wanting a high carrier fref]iiency arise from a con-sideration of bandwidth. Any hollow conductor waveguide has a cutofTcharacteristic of the form sketched in Fig. 5. Above cutoff the groupvelocity approaches asymptotically to the velocity in an unboundedmedium composed of the dielectric used in the waveguid
