Optimization of a Double-Sided Flexible Printed Cable

Electromagnetic pulses, especially ultra-wideband (UWB) interference, pose a significant threat to radio electronic devices (REDs). They lead to functional failure or lesions. To protect against such interference, modal filters (MFs) are investigated. They can be realized at different structural levels. For example, they can be realized in flexible printed cables (FPCs), which have found widespread use in various REDs in recent years. In this paper, we evaluated the effect of radio-absorbing material (RAM) on the attenuation of UWB interference in FPC with real parameters. Thus, the addition of RAM achieved an attenuation of 7.3 times (Umax=0.136 V) with respect to half the e.m.f. However, this attenuation was achieved with a negligible difference in per-unit-length mode delays (which amounted to 0.305 ns/m). This leads to an increase in the length of FPC. To reduce it, we performed cross-sectional optimization. Optimization was performed with real parameters of single-layer foiled polyimide. We, have shown how the conductor spacing and width affect the amplitude of the decomposition pulses and the difference of the per-unit-length mode delays. Thus, optimization made it possible to increase the attenuation up to 11.5 times (Umax=0.087 V) and the difference in per-unit-length mode delays up to 2.98 ns/m. This research shows the possibility of sufficiently large attenuation of UWB interference in the FPC without using additional protection devices.