Experimental Study of a Structure With Single Modal Reservation Before and After Failure

This article presents the results of an experimental study of a structure with single modal reservation (MR). The decomposition of an ultrawideband (UWB) pulse in such a structure before and after failures has been demonstrated for the first time. For this case, authors used two bell-shaped pulses with a total duration of 0.15 and 1.5 ns. The frequency dependences of the transmission coefficient magnitude |
S
₂₁
| were measured for the manufactured prototype in the range from 10 MHz to 18 GHz. The results demonstrate that the structure before and after failures acts as a low-pass filter. To confirm the results of the experiment, its numerical simulation was carried out using two approaches: quasistatic and electrodynamic. In doing so, we took into account losses in conductors and dielectrics. To numerically estimate the criticality of the voltage waveforms obtained during the experiment at the output of the reserved circuit before and after failure, we calculated the
N
-norms. The simulation and experimental results in the time and frequency domains agree quite well. It was shown experimentally that after failures the maximum changes in the cutoff and the resonant frequencies are 45% and 19%, respectively. This suggests that after failures, the results may not coincide with the predicted ones, which must be taken into account when designing real structures with MR. It was found that in the time domain after failures, the maximum amplitudes of the decomposition pulses at the far-end of structure with a single MR change, and these changes depend on the duration of the UWB pulse at the input. This influence is explained by the length of the traces to SMA connectors. If the double delay in the trace is greater than the total pulse duration, then after failures, the amplitudes will not change, since the reflected pulses will not be superimposed on the main ones. However, as the length increases, the UWB pulse will be superimposed on the main ones and will change the maximum amplitude. This effect must be taken into account during design process as it can affect the interference immunity and functional safety of the device. This is shown in the analysis of
N
-norms.