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BELL SYSTEM TECHNICAL JOURNAL 



longer lengths it is effective over a broad range of frequencies. This is 

 illustrated by Fig. 9 which is a plot of the wire length versus the tilt 



4 6 6 

 WIRE LENGTH IN WAVE LENGTHS 



Fig. 9 — -Optimum tilt angle for long wires. 



angle utilizing the above mentioned rules. For example, if the antenna 

 were designed for a frequency such that the wire was ten wave-lengths 

 long but it was used at another frequency where the wire length was 

 only eight wave-lengths, Fig. 9 shows that the inaccuracy of tilt angle 

 would be only about two degrees, which in most cases is inappreciable. 

 As we shall see later, even this inaccuracy can be compensated by 

 another wire in combination having an opposite trend. 



Broad Frequency Range in Arrays 



As is true for any antenna, the tilted wire may be used as an element 

 in all the usual forms of arrays. Successful experimental antennas 

 have been constructed consisting of a succession of tilted wires disposed 

 in broadside relation, in the line of transmission and also stacked one 

 above another. Some of these arrangements confine the effectiveness 

 of the resulting antenna to a single frequency. Appreciating that one 

 of the principle features of the tilted wire was its eft'ecti\^eness over a 

 broad frequency range, we have particularly stressed the development 

 of those combinations of tilted wires which would not place restrictions 

 on this frequency range. One such combination is discussed in the 

 following section. 



