Theoretical and experimental methods for evaluating discontinuities in microstrip

Typical microwave circuits includes various circuit elements interconnected by sections of transmission line having a range of characteristics impedances. The resulting junctions and discontinuities are associated with parasitic effects which can severely modify the circuit operation. Available theoretical and experimental methods for evaluating such discontinuities are reviewed. The advantage of the experimental technique described is that it is accurate enough to confirm the theoretical work while the nature of the theoretical methods prevents a realistic error analysis in many cases. Because it is difficult to adjust the circuits after fabrication, it is essential to include the equivalent circuit of the discontinuity in the original design. A microwave FET amplifier is considered for illustrating the effects of discontinuities on practical design.