why the poles of polyphase filter are logarithmicaly spaced

Dear all, why the pole frequencies are logarithmically spaced? It is said to get equiripple response. But I wanne know more details. Could anyone enlight me on this topic or up load some reference?

I know a paper

R.C. V. Macario and I.D. Mejallie, "The phasing method for sideband swlection in broadcast receivers" EBU Rev. (Technical Part), n. 181, pp. 119-125,1980

Could anyone of you please upload this paper?

Thank you in advance.