A. M. Zabolotsky

UWB Pulse Decomposition in Simple Printed Structures

The paper describes the ultra-wideband (UWB) pulse decomposition in simple printed structures aimed at low-cost and effective protection. The structure of an asymmetrical modal filter without resistors is considered, and the possibility of the attenuation by a factor of 55 is shown. Another structure—a turn of a meander line (ML)—is described, and the possibility of the attenuation by a factor of 2.5 is shown. Simulations without and with frequency-dependent losses in conductors and dielectrics are compared with experimental results. Based on the described principles, new devices can be designed which will be reliable, cheap, and radiation resistant due to the absence of any lumped components.

Improved design of modal filter for electronics protection

A new structure of modal filter which is more relevant for lightning protection of electronics than previously considered structures is proposed. Decrease of modal filter length or increase of original pulse width by factor of 10 and increase of modal filter attenuation from factor of 2 up to factor of 5 is shown. Condition for equal magnitudes of decomposed pulses and analytic formula for their values against a ratio of even to odd mode characteristic impedances are derived. Dependence of these values on coupling is shown for practical parameters of the new structure based on FR-4. On the basis of the calculated data an experimental prototype of an improved modal filter has been made. An experimental investigation has been performed.

Pulse decomposition in the turn of meander line as a new concept of protection against UWB pulses

Pulse decomposition in the turn of a meander line with the homogeneous dielectric filling is analyzed in detail. The study shows that the ultrashort pulse in the turn of a line with strong half-turn coupling is decomposed to subsequent pulses, having levels of 60, 60, -40, 20, -10%, when compared with a signal in the beginning of the turn. We obtained the conditions, providing decomposition of an ultrashort pulse into subsequent pulses. The research reveals the optimum value of capacitive coupling coefficient, being equal to 0.9, and providing the minimum level of pulses in the line end.

Simple method of protection against UWB pulses based on a turn of meander microstrip line

The possibility of protection against ultrawideband (UWB) pulses, based on the combination of distortions in a meander together and modal decomposition phenomena, is shown on the example of meander microstrip line. It is revealed that UWB pulse at the end of a line can be decomposed into a sequence of pulses of lower amplitude not exceeding 40% of the pulse level at the beginning of the line.

Maximization of duration of ultrashort pulse that is completely decomposed in multiconductor modal filters

Paper considers improvement of the protection against ultrashort pulses by means of optimization of parameters of multiconductor microstrip lines. We have obtained three-, four- and five-conductor strip lines which will help to maximize duration of a pulse that will be totally decomposed in these structures. It was achieved by means of equalization of time intervals between decomposition pulses. The maximum amplitudes of the decomposition pulses were 2,2; 2,3 and 3,9 times less than the pulse at the near end of the line. The results have shown that it is important to optimize multiconductor modal filters considering both minimization of amplitude of an output signal and maximization of duration of a decomposed pulse.

New printed structures for protection against UWB pulses

Two new simple printed structures providing low-cost and effective protection against ultrawide band pulses are proposed. The possibility of the 20 times attenuation for the structure of asymmetrical modal filter without resistors is shown. The possibility of the 2.5 times attenuation for another widely spread structure - a widely spread turn of a meander line - is demonstrated. Devices based on the proposed structures will be reliable, cheap and radiation-resistant due to the absence of any components.

Influence of ultrashort pulse duration on its peak values localization in PCB of spacecraft autonomous navigation system

Importance of research on specific aspects of ultrashort pulse propagation and voltage peak values localization along printed circuit board (PCB) multiconductor bus is highlighted. Simulation of a trapezoidal ultrashort pulse propagating along conductors of the bus with a different number of excited conductors, fixed variation of the whole ultrashort pulse duration (3; 0.3; 0.03 ns) and a duration optimized by genetic algorithms has been carried out. In the case of one excited conductor, the maximum value exceeds by 18% the ultrashort pulse amplitude at the input and the greatest (by modulus) minimum value is −36% of 0.5 V level lower the level of zero. In the case of two conductors, the highest maximum value exceeds by 20% the ultrashort pulse amplitude at the input and the minimum is −40% of 0.5 V level lower the level of zero. It is shown that significant signal excess is observed with decreasing of ultrashort pulse duration both for maximum and minimum. Also, localization of voltage peak values is inconstant: they appear in different parts of PCB bus including different PCB layers. With the usage of optimization, a voltage maximum in the given conductor exceeds the 0.5 V level by 16%, when the whole duration of an ultrashort pulse is near 0.13 ns.

Optimization of parameters of multiconductor modal filters for protection against ultrashort pulses

Paper considers improvement of the protection against ultrashort pulses by means of optimization of parameters of multiconductor microstrip lines by different criteria. We have obtained a three-conductor microstrip line with the maximized difference of delays between the first and the last decomposition pulses. It was achieved by means of expansion of time intervals between decomposition pulses. At the same time, signal amplitude at the output of a line considerably decreases (almost twice). The results have shown that it is important to optimize multiconductor modal filters considering both minimization of amplitude of an output signal and maximization of difference of delays between the first and the last decomposition pulses.

Experimental results on ultra wide band pulse propagation in three-conductor power cables of flat and circular cross sections

This paper presents some experimental results of unusual propagation of an ultra wide band pulse in low-voltage installation three-conductor power cables. For cables of flat cross section, the results confirm the possibility of modal decomposition of a pulse into two low level pulses. However, this phenomenon does not appear in cables of circular cross section.

Experimental confirmation of the modal filtration in four- and five-conductor microstrip lines

An experimental confirmation of modal filtration based on multiconductor microstrip lines is executed. Authors designed four- and five-conductor prototypes of modal filters (MF), which have the maximum amplitude of the decomposition pulses of 12.6 and 15.3 times less in comparison with the initial signal. The results showed the prospect of research of multiconductor MF because addition of conductors to the initial structure additionally (up 2.3 times) decreases the amplitude of the initial signal at the end of the active conductor.