Optimization of a Modal Filter Realized on a Double-Sided Printed Circuit Board

Abstract

This paper considers the protection of radioelectronic equipment from the effects of ultra-wideband interference. This paper presents the results of optimizing the cross section parameters of the modal filter (MF) realized on a double-sided printed circuit board. Two configurations of the filter are considered: when the reference conductors are connected only at the ends of the line and when they are connected along the whole length of the filter. For the optimized parameters, the results of attenuation are presented when the boundary conditions at the ends of the passive conductor are changed from the matched to open circuit (OC) or short circuit (SC). It is shown that when the reference conductors are connected only at the ends and the distance between the signal and reference conductors is small, three pulses come to the MF output. When the reference conductors are connected along the entire length, there are two of them. For the MF on a double-sided PCB with reference conductors connected only at the ends, the attenuation reached 3.2 times the half e.m.f., and the difference of the per-unit-length mode delay was 2.35 ns/m. For OC-SC, the attenuation was 5.4 times. The differences of the three per-unit-length mode delays (1.065 ns/m) were maximized and aligned. For the MF with reference conductors connected along the entire length, the difference of per-unit-length mode delays was 2.424 ns/m, and the attenuation was 3 times for the matched case and 5.5 times for OC-SC.