I am an EE presently writing a book on microwave semiconductors. In one of the common graphs we employ - the Smith chart - we use the bilinear transformation to map rectangular regions to circles in the transformed domain. Does anyone from the math world know of a simple proof to demonstrate the uniqueness of the line connecting the centers of two arbitrary circles that is everywhere orthogonal to the tangent points of the associated contours? And, is there a way to extend this to higher dimensions.
Thanks so much...
John Sevic