An error was incurred in the writing of the derivatives of three functions with Kronecker delta terms. This error also resulted in incorrect expressions for some radiation patterns presented in the article. It is important to emphasize, however, that all the figures and corresponding analysis were performed using correct expressions given below. Therefore, the error only affects how some equations were written in the article.

The correct derivatives for the functions in equations 18, 19 and 20 (the latter also referred to in equation A-20 in Appendix A and equation C-10 in Appendix C), are  
xiδ...
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