Julia, Here is my understanding of the sentence. The result of a comparison of alternatives determines the range of effective use of antenna supports with weighted foundations and their optimum heights. Weighted foundation: foundations with additional weights to ensure bearing capacity against shearing.

Тут и по русски -то понять сразу сложновато.;) Я бы так перевёл.. As a result of the comparison of options has been defined an area of effective applications to the antenna's supports with upweighted foundations and theirs optimum heights. The upweighted foundations imply in their meanings the foundations with additional weights to provide a carrying capacity against the breakage by tension.