Novel Wide Band Microstrip Balun

This paper presents a novel wide band microstrip BALUN, composed of two parts. The first one is a compensated Wilkinson power divider which provides a good power separation between the two output ports. The second is a passive phase shifter composed of two filters consisting of 3 dB 90° hybrid couplers, the coupled and transmitted port being short circuited (c.c. arm) or open circuited (c.c. arm). The results of the theoretical analysis are presented. The experimental results presented below are valid over the 5-11 GHz band and contain the coupling between input and output ports as well as phase shift and isolation : output 1 : 3.6 dB ± 0.3 dB output 2 : 3.6 dB ± 0.5 dB phase shift : 170° ± 5° isolation ¿ 14 dB It is believed that with slight improvements, such a structure can be successfully used in wide band solid state microwave amplifiers including push-pull stages.