Serpentine and Spiral Routing Schemes for Microwave Transmission Lines to Ensure UWB Interference Immunity

This article analyzes novel, adventurous routing schemes employed in designing microwave transmission lines (TL). In contrast to traditional schemes, we propose to locate two independent traces close to each other. The strong electromagnetic coupling thus formed can cause unwanted crosstalk between traces. However, if their level is acceptable, we can use the suggested routing schemes to significantly increase the powerful interference immunity of the electrical circuits by using modal distortion. Two prototypes of such TLs in the form of a serpentine and a spiral were made in which the far-end crosstalk voltage waveforms do not exceed 4.4% of the useful signal amplitudes. We performed electrodynamic simulations and measurements of such TLs in a transverse electromagnetic cell in the frequency range from 10 MHz to 5.3 GHz. The investigated lines have a low level of radiated emissions. Experimental results show that the proposed TLs decrease the voltage amplitude of the ultra-wideband pulse by at least 4 times and the voltage change rate by 10.7 times and more. In addition, the effective voltage value on the load is decreased by at least 2.2 times. The spiral scheme was found to be better than the serpentine scheme in almost all parameters. Simultaneously, the electrodynamic approach is in full agreement with the experimental study.