T. R. Gazizov

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.

Environmental shielded TEM chamber for biomedical testing

A problem of microwave exposure of biological systems is considered. An urgent need to reveal mechanisms of thermal and nonthermal biological effects of radiation is emphasized. A concept of joint control of shielding, temperature, and humidity for object under exposure is proposed. To implement this concept use of an environmental shielded TEM chamber for biomedical testing is suggested.

Design of printed modal filters for computer network protection

Preliminary results of simple printed structures (modal filters) design for mitigation of short pulse lightning effects on computer networks are considered. For two types of two-conductor coupled lines on a dielectric substrate the L, C, Z matrixes, per unit length propagation delays and their absolute and relative differences are calculated. These differences are maximized using the parametric optimization of conductor width and separation by genetic algorithms for substrate thickness 0.5 mm and relative permittivity 5. It is demonstrated that differences of per unit length propagation delays for specially designed printed structures may be considerably more than the one for existing flat cables. Proper use of similar structures is proposed for lightning protection.

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.

Evaluation of efficiency of modal filtration in different types of redundant electrical connections

Electrical connections of control and communication systems are considered. We have computed electrophysical parameters for the considered types of coupled electrical connections in a wide range of parameters applied in practice. If we take into account real length of interconnections, duration of an interfering pulse go up to 37 ps for integrated circuits (IC), 6 ns for printed circuit boards (PCBs) and 19 ns for flat cable, attenuation coefficient for an interfering pulse is 2.1…2.8 times. Range of frequencies that assure the maximum attenuation of an interfering pulse for IC is higher than 13 GHz, for PCB it is higher than 143 MHz, for FFC it is 26.240 MHz. These results prove efficiency of modal filtration in different types of redundant electrical connections of communication and control systems.

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.

Impedance of low-frequency passive components of spaceborne equipment at frequencies ranging to 20 GHz

The paramount importance of studying the impedance of low-frequency passive components of spaceborne equipment at frequencies ranging to tens of gigahertz is shown. The preliminary results of measurements of the resistor and capacitor impedances at <20 GHz are presented and analyzed. The significant difference between the ideal elements, the classical models, and the available components is demonstrated. The models of the resistor and capacitor for a frequency as high as 1 GHz are obtained.

Simple and free mitigation of short pulse lightning effects by flat power cables

Three-conductor flat power cables as simple and cost free mitigation of short pulse lightning effects are considered. For six types of commonly available cables their L, C, Z matrixes, per unit length propagation delays and their differences are calculated. It is shown that proper use of inherent properties of similar cables is possible for lightning protection. It is demonstrated that flat cables without air gaps in cross section are more suitable for this aim.