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of the exciting e.m.f. and that the phase difference between successive 

 current maxima is 180 deg.^ Such a conductor when folded in a vertical 

 plane 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 the 

 instantaneous currents in all the vertical members are in the same direc- 

 tion and that in the cross members their directions are opposed. Due 

 to these current relations and the physical positions of the elements, 

 the cross members radiate a negligible amount of energy whereas the 

 vertical members combine their effects for the directions perpendicular 



3 This assumes of course that the conductor is in space free frorn objects affecting 

 its electrical properties and that the ends are free or properly terminated to produce 

 reflections. 



