Low cost millimeter wave duplexer design using mixed mode-matching and integral contour methods

A millimeter wave H-plane duplexer using E-plane filters has been designed. T-junction is used for connecting the channel filters compensated by cylindrical post and analyzed by integral contour method. Moreover the junction discontinuity effects have been taken into account. The combination of filters and compensated T-junction allows for low-cost manufacturing. The E-plane filters are analyzed separately, by mode matching method. The scattering parameters of the combination of filters and T-junction are obtained. The diameter and position of the compensating rod and length of T arms are optimized to achieve desired performance. This procedure saves time and memory in computations. The 38 GHz duplexer has been built and tested. The theory has been verified by measurement.