Design of a Ultra-Wideband Passive Combining Circuit

This paper introduces about a ultra-wideband passive combining circuit, with low frequency band of DC ~ 38GHz and high frequency band of 38GHz ~ 70GHz. The circuit is realized through two microstrip lines coupled structure. High frequency band signal is coupled from one microstrip line to another line's remote end, on which low frequency band signal is transmitted. High frequency band signal and low frequency band signal is combined to form wideband output signal. This circuit adopts 0.127mm ceramic substrate. Insertion loss is less than 5dB at whole band and less than 2dB at 70GHz. Isolation is better than 15dB between two paths. This circuit has been widely applied in wideband vector network analyzer, signal generator and so on.