. The Bell System technical journal . o arrange a large number of radiating elements in a vertical planearray, spacing them at suitable distances and interconnecting them insuch a manner that the currents in all the radiating members are inphase. A simple way of accomplishing this result and the one whichis now being employed at Lawrenceville depends upon the manner inwhich standing waves are formed on conductors. It is generally knownthat current nodes and current maxima will recur along a straightconductor whose length is an exact multiple of one half the wave-length 276 BELL SYSTEM TECHNICA
. The Bell System technical journal . o arrange a large number of radiating elements in a vertical planearray, spacing them at suitable distances and interconnecting them insuch a manner that the currents in all the radiating members are inphase. A simple way of accomplishing this result and the one whichis now being employed at Lawrenceville depends upon the manner inwhich standing waves are formed on conductors. It is generally knownthat current nodes and current maxima will recur along a straightconductor whose length is an exact multiple of one half the wave-length 276 BELL SYSTEM TECHNICAL JOURNAL of the exciting and that the phase difference between successivecurrent maxima is 180 deg.^ Such a conductor when folded in a verticalplane as shown in Fig. 3 and with its length adjusted slightly to com-pensate for the effects of folding, satisfies the aforementioned require-ments for producing directional radiation. The arrows in Fig. 3 indi-cate the relative directions of current flow and the dotted line indicates. Fig. 3-—Conductor bent to form one section of simple directive antenna. The type used for transmitting at Lawrenceville. the current amplitudes along the conductor. It will be noted that theinstantaneous currents in all the vertical members are in the same direc-tion and that in the cross members their directions are opposed. Dueto these current relations and the physical positions of the elements,the cross members radiate a negligible amount of energy whereas thevertical members combine their effects for the directions perpendicular 3 This assumes of course that the conductor is in space free frorn objects affectingits electrical properties and that the ends are free or properly terminated to producereflections. TRANSOCEANIC TELEPHONE SERVICE 277 to the plane of the conductor. In other directions destructive inter-ference reduces the radiation from the vertical members. The systemis equivalent to four Hertz oscillators driven in phase, and arra
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