DEVELOPMENTS IN SHORT-WAVE DIRECTIVE ANTENNAS 675 



The use of the antenna horizontally, in the usual short-wave range, 

 assumes that the strength of horizontally polarized waves are at least 

 as great as are the vertically polarized components. Several observers 

 have reported them more so, but the experience of the writer has been 

 that there is little choice where horizontal and vertical antennas, hav- 

 ing the same degree of directivity and optimum direction, are com- 

 pared. 



Up to this point in this paper, the attempt has been made to present 

 simply a broad picture of some of the applications of long tilted wires to 

 antenna design. It now seems worth while to give in somewhat more 



2 3 4 5 6 



HEIGHT OF ANTENNA H IN WAVE LENGTHS 



Fig. IS — Vertical plane design chart. 



detail a sample of the design methods employed and the performance 

 measurements on one typical form of antenna; accordingly a medium 

 size horizontal diamond-shaped antenna has been selected. 



The Horizontal Diamond-Shaped Antenna 



In calculating the directive diagrams of the horizontal diamond- 

 shaped antenna, the antenna wires have been assumed to be without 

 resistance. As long as we are contented in knowing only the relative 

 shape of the directive diagrams, this approximation is quite accurate 

 and results in a tremendous simplification of the problem. 



In all of the calculations, a perfect ground has been assumed. For- 

 tunately, for horizontally polarized waves, variation in the ground con- 

 stants do not radically affect either the amplitude or phase of the 

 ground reflections, so that the following equations can be used as rough 



