Experimental Study of the Electrical Characteristics of a Modal Filter on a Double-Sided PCB without an Upper Reference Conductor

Abstract

The paper presents the experimental study that proves the possibility of an ultrashort pulse (USP) decomposition into a sequence of pulses of smaller amplitude in a modal filter (MF) on a double-sided printed circuit board (PCB) without an upper reference conductor. The cross section parameters of the filter were optimized to manufacture a laboratory model. The results of modeling the effect of t (foil thickness), s (conductor separation), and w 1 (width of active and passive conductors) on the decomposed pulse amplitudes are shown in more detail. More specifically, they demonstrate that for given values of t and s, there is a value of w 1 at which it is possible to achieve equalization of the pulse amplitudes at the MF output. Based on the optimization results, an MF layout was made. Quasi-static simulation was performed to validate the measurement results. In the experimental study, the attenuation was 6.6 times the half e.m. f., and the bandwidth was a MHz. Changing the boundary conditions at the ends of the passive conductor to short-circuit (SC) and open-circuit (OC) failures increased the attenuation to 7.7 times and the bandwidth to 70.5 MHz. In addition, the appearance of additional pulses during SC-OC is shown. The time of arrival of these pulses is determined by a linear combination of per-unit-length delay of the modes multiplied by the line length. The experimental and simulation results are in good agreement.