Evaluating References, Categorization, Authors, Seminal contributions.
The classic conformal mapping approach proposed by Carrel  followed the arguments used at the time for stripline and similar structures.
Because of errors in Carrel’s work, it was later shown to be applicable to the flat bowtie case only, and Lambert, Booker and PD Smith suggested improvements , which extended the use of analytical methods to general folded bowties.
Once again, it was shown  that the predicted values of  were in error, and only valid over a limited range.
In , a complete theoretical analysis is finally presented, and evaluated. However, in this work it is also shown that, for the dimensions generally of interest, the full analytical solution is not necessary: a simple approximation, where the structure is treated as two back to back microstriplines with an air dielectric, suffices.