Ultra wideband tapered power combiner/divider

Abstract

Many typologies like the designs of Wilkinson Power Divider and Gysel Power Divider have been worked and improved through the years. Each design targets a higher bandwidth, a better isolation and a higher power handling capacity or smaller size. The basic analysis of every structure begins with the even mode and the odd mode models. The tapered lines are ultra wideband matching structures that are used to match real impedances. The only limitation of tapered line is the size, which has to be the half wavelength of the lower frequency limit. The tapered lines do not have any upper frequency cut-off. Because of the limitations in sizes, tapered lines have not been able to be used very commonly. The proposed new topology has a new taper topology with a single capacitor at the input side to decrease the lower frequency limit of the tapered line. The even mode structure of the proposed power divider/combiner is constructed of these improved tapered lines. In the odd mode analysis, the N section Wilkinson power divider/combiner design has been used. In order to determine the isolation resistor values, four different methods have been proposed. The proposed structure uses the surface resistive materials to implement these resistors. It has been observed that continuity of the isolation resistors between transmission lines causes some loss in the even mode. In order to solve this problem, the width of the resistors should be as small as possible to prevent the even mode loss.