Discussion on optimum patterns for endfire arrays

The method of synthesizing an equal-minor-lobe directivity pattern suggested by Riblet for the broadside array was applied recently by DuHamel to the case of the endfire array. In the present paper, an alternative synthesis procedure is described, based directly on Dolph's method of synthesis for the broadside array. Advantages of this alternative procedure include (a) applicability to arrays having even as well as odd numbers of elements, and (b) somewhat simpler equations for calculating relative currents for the elements of the array. This alternative procedure is described here in detail, together with numerical examples for the seven-element array used by DuHamel and for a four-element array. A tabulation of equations for relative current amplitudes for arrays of 5, 7, 9, 11, and 13 elements is given in an Appendix. In conclusion, an alternative method of overdesigning a supergain antenna is described.