Analysis of the Noise Voltage Coupling (Crosstalk) Between Right-Handed and Composite Right/Left-Handed (CRLH) Transmission Lines on Printed Circuit Boards

One aspect of the electromagnetic compatibility (EMC) analysis of RF circuitry is the accurate modeling of the coupling between printed transmission lines. Correct modeling of this coupling is essential because unwanted noise voltages can be substantial and create adverse effects on sensitive components. Recently, the development of composite right-/left-handed transmission lines (CRLHTLs) has received considerable attention due to the unique propagation characteristics. Because of this increase in applications, CRLHTLs are being implemented in RF systems with other printed circuitry, such as microstrip transmission lines, in very close proximity. In many of these instances, the coupling may not be intentional. To study this interaction between CRLHTLs and other printed circuitry from an EMC point of view, this paper presents derived analytical expressions for computing the nearand far-end voltage coupling between right-handed (printed microstrip transmission lines) and CRLHTLs. More specifically, these expressions are used to determine the nearand far-end voltages weakly coupled to the CRLHTL when the conventional microstrip right-handed transmission line is driven with a source and terminated with a load. These expressions are then used to illustrate how the induced voltages on the CRLHTL can be reduced by the capacitance and inductance values that support left-handed propagation. This can be a useful alternative to conventional shielding. Furthermore, design guidelines and tradeoffs are presented on the layout of CRLHTL near other printed transmission lines. The expressions derived in this paper are validated with simulations and measurements.