Analysis of cross-talk and discontinuity problems in microstrip lines

ABSTRACT: In this thesis, microstrip line problems such as crosstalk and discontinuity that may occur in the microwave circuits have been studied in line with the literature and simulations have been carried out by using FEKO 5.5 full wave simulation software. The crosstalk problem is studied in three sections. The first section deals with the effect of placing rectangular trace between the strips, which is connected to the ground. With the proposed design 7dB of reduction has been observed in the Far-End crosstalk (FEXT). In the second section, perpendicular rectangular metals with Via fences connected to the Guard trace (RVG) have been used and FEXT enhancement of 7dB was observed. In the last section, Cross shape metals with via fence were connected by Guard trace (CVG) and The FEXT was reduced by 8dB. The results are compared with spacing rule results for S = 3W. The discontinuity problem that occurs in right angle and step-width microstrip lines may be reduced by two types of chamfered methods. i.e. angle chamfered and tapered chamfered methods. In this study, a novel design has been applied to reduce the discontinuity problem by using tapered line on both sides of transmission lines. Simulation results show an improvement in reflection coefficient for 23 GHz (7-30) GHz bandwidth (BW) when compared with the step-width without chamfered. For the bend discontinuity, it was found out that the improvement in the reflection coefficient with a 70% chamfered ratio compared with 50% ratio is about 4dB for 70 GHz BW. Keywords: Coupling, FEXT, NEXT, Microstrip discontinuity, FEKO, RVG, CVG, Chamfer, taper, Via fence. …………………………………………………………………………………………………………………………………………………………………………………………………………