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Technique and results of testing of general-purpose electronic, radio communication, and industrial equipment for susceptibility to powerful ultra-wideband electromagnetic (EM) pulses is presented. An example of the implementation of the developed technique is given using equipment that provides exposure in form of series of electromagnetic pulses with amplitude of up to 50 kV /m, duration of 220–250 ps, and rise time of 120–150 ps. A pulse repetition rate is from 100 Hz to 1 kHz and duration of pulse train is from 0.1 to 300 s. The test results confirm the significant effect of EM pulses impact on the performance of the set of tested radioelectronic products of general purpose for pulse amplitudes of 1… 50 kV/ m.

The analysis of EMC between medical short range devices of body area network system, capsule endoscopy system, active implant system and wireless equipment of mobile stations of cellular communications (LTE and 5G), RLAN equipment, NB IoT sensors operating inside a hospital building is performed. The integrated interference margin is used as a criterion of EMC. Results of the analysis show the following: 1) the equipment of wireless systems can create the interference to all considered types of medical short range devices (as well as medical short range devices can create the interference to receivers of the wireless systems) in case of allocation of emitters and receptors inside the same room or in neighboring rooms; 2) in order to ensure EMC of considered systems, it is advised to set more stringent requirements on characteristics of susceptibility of the medical equipment to radiofrequency electromagnetic fields created by wireless equipment of 4G/5G networks as well as on spurious emissions of transmitters of wireless systems. The results can be used in diagnostics of intersystem EMC in order to ensure safety of use of mobile wireless telecommunication equipment regarding medical vital devices in conditions of mass distribution of 4G/5G wireless information services in hospitals.

A worst-case model of spurious resonances which can occur in electromagnetic system consisting of an antenna, cable and transmitter output filter (or receiver input filter) is proposed. These resonances may cause significant increase in power of spurious emissions for transmitting equipment and the decrease in out-of-band radiated susceptibility levels for receiving equipment. Three amplitude-frequency characteristics (AFCs) are the initial data for the model synthesis: AFC of the cable attenuation, AFC of the transmitter output port impedance (or AFC of the receiver input port impedance), and AFC of the antenna input impedance. It is assumed in the model that the cable length and phases of the impedances are unknown, therefore, at each frequency, the maximum possible increase in power of spurious emissions or the decrease in radiated susceptibility levels is estimated. Validation of the developed model is performed by numerical computation of an equivalent circuit containing a circuit-level model of the transmitter output filter, two-port network described by scattering matrix of the cable and one-port network characterized by the antenna input impedance. Measured AFC of the input impedance for antenna S65-8262-2, calculated AFC of the attenuation in radio-frequency cable RG58, and parameters of the transmitter output filter (pass band, attenuations in pass band and stop band, shape factor) are used as initial data for the validation. As a result of the numerical modeling, the influence of the cable is estimated: the AFC maximum for ratio of spurious emission power accepted by the antenna to the power of this emission accepted by the 50 ohm load is 7.7 dB; the AFC maximum for ratio of spurious emission powers accepted by the antenna using 2 m cable and without the cable is 29 dB. The validation demonstrates the worst-case behavior of the developed model.

A worst-case wideband model for estimation of effectiveness of electric and magnetic field shielding by a rectangular metallic enclosure, the walls of which can contain rectangular or circular apertures, is developed. The model is based on a combination of analytical solutions of the following two problems: transmission of electromagnetic radiation through the aperture and propagation of the radiation in lossy waveguides. The analytical solutions ensure high computational efficiency of the model in a wide frequency range. The developed model makes it possible to estimate the effectiveness of external field shielding by a metallic board-system hull (the hull of a car, aircraft, ship, etc.) the internal compartments of which can be approximated by a rectangular waveguide. In order to do this, it is necessary to define the amplitude-frequency characteristic (AFC) for the loaded Q-factor of the compartment under consideration. Such AFC takes into account the presence of objects inside the compartment as well as the field absorption in the compartment walls, and it can be calculated (analytically or numerically) or measured. The developed model is validated by comparison of calculation results obtained by the model with known experimental results and with results of numerical simulation (ratios of the wavelength to the maximum dimension of the enclosure from 0.1 to 1000 are examined). Examples of modeling of the shielding enclosures containing the apertures of various sizes and shapes (circular, rectangular with different ratios of the sides) are considered; the number of apertures is varied from 1 (window) to 1000 (mesh).

Results of discrete nonlinear behavior simulation of aircraft wireless systems' operation in complicated electromagnetic environment (EME) created by electromagnetic radiations of wireless systems allocated on the earth's surface and in different surrounding airborne vehicles are presented. The simulation is performed with the use of technique of virtual testing area; this technique is based on implementation of geoinformation technologies for analysis of different scenarios of influence of unwanted signals on wireless systems of aircraft flying at low and medium altitudes. Results of simulation prove the presence of real danger of intermodulation interference in onboard VHF/UHF radio receivers of piloted aircraft in case of complicated EME at small and medium altitudes if unmanned aerial vehicles approach to the aircraft at distances which are acceptable from the viewpoint of air traffic control regulations.

A technique of two-phase EMC diagnostics of complex ground-based radio systems with the use of worst-case models of electromagnetic spurious couplings between antennas is introduced. At the first phase, the ultra wideband analytical model of antenna coupling developed in the framework of IEMCAP program is used, and the ensemble of potentially dangerous spurious couplings is found. For these couplings, the improved numerical worst-case models for the reduced frequency bands, as well as for given types, orientations, and relative positions of the antennas are developed at the second phase of EMC diagnostics. Each of these improved models is obtained by finding the envelope of results of multiple (based on variations of model parameter values) FDTD modeling of the corresponding coupling. The example of application of the introduced technique for diagnostics of intrasystem EMC of an operating radio-TV complex is provided: the computer model of its radio mast is developed, and the two-phase EMC diagnostics of this complex (which contains radio equipment of more than 20 systems of radio-TV broadcasting, fixed and mobile radio communication, radio navigation, and other services) is performed. The obtained results have confirmed the efficiency of the presented technique for the analysis of intrasystem EMC due to significant improvement in estimation of potentially dangerous spurious couplings between antennas at the second phase of EMC diagnostics (by 5…20 dB in comparison with analytical model of IEMCAP) with acceptable computational burden.

A computationally effective wideband worst-case model of spurious coupling between monopoles placed at line of sight of each other is proposed. The model is constructed by combining analytic solutions of the problem for low-frequency and high-frequency bands by means of weight function determined empirically. The low-frequency solution is used at frequencies below the main resonance frequency of the longer monopole, and it is based on induced emf method. This solution takes into account the mismatch of antennas with a source and a load, and it is validated in three-decade frequency range. The high-frequency solution is based on the equation for free-space transmission of radio waves. The model can be used in the framework of express analysis of EMC to calculate mutual influence of monopoles installed on the fuselage of an aircraft. Validation of the proposed model and determination of its applicability region are performed by comparing results computed by the model with results of numerical modeling by the method of moments (MoM) for the following values of parameters: ratio of the fuselage diameter to the antenna length is varied from 1.75 to 12.5, ratio of a distance between the antennas to the antenna length is varied from 1.00 to 12.5. For additional validation, the comparison of results computed by the proposed model with results of numerical modeling by the finite element method (FEM) for two blade antennas AT-1076 installed at KC-135B airplane is performed.

In this paper, we developed an analytical model that makes it possible to estimate the response (i.e., the voltage or current at the output) of a dipole antenna to arbitrary-shaped electromagnetic pulse if the minimum information about the antenna is available (it is enough to know the following parameters of the antenna: working frequency range, gain, and wave impedance of the radiofrequency port). The developed model is validated by comparing the computed responses of VHF- and UHF-band dipole antennas to wideband electromagnetic pulses with the measurement results published in the literature. The validation demonstrates that the model estimates the values of the most important antenna-response parameters (total energy, amplitude, and voltage rate), which define the requirements to the radio-equipment terminal protection devices, with reasonable accuracy. The possibilities of increasing the response estimation accuracy by numerical modeling of the antenna are investigated (MoM and FDTD methods are involved).

A worst-case computationally-effective model for analysis of coupling between on-board antennas mounted on the conducting hull of a system (aircraft, ship, car, etc.) is proposed. Consideration of electromagnetic wave diffraction by the arbitrary-shaped hull is based on combining of the model for calculation of shading by convex surfaces of rotation bodies (cylinder, cone) and the wedge diffraction model obtained in the framework of the Uniform Theory of Diffraction (UTD). The proposed model of antenna coupling is validated by comparison with results of experiments and numerical simulation (by FDTD and GTD-PO methods) in a wide range of parameter values: cases of monopole and dipole antenna mounting in various points of the aircraft hull with several mutual orientations are considered, the frequency is varied from 50 MHz to 7 GHz, the ratio of wavelength to diffraction-path length is varied from 0.001 to 1.

A technique for calculation of currents in transmission lines in a wide frequency range is proposed. The technique is based on a generalization of the lumped-circuit calculation methods to the case of long transmission lines by the introduction of refinement functions. A worst-case model for the amplitude-frequency characteristics of currents in the transmission line is developed on the basis of the proposed technique. The model is intended for diagnostics (express analysis) of electromagnetic compatibility in complexes of radio and electronic equipment. Worst-case nature of the model is provided by construction of the envelope of the current's maxima (observed at resonances) for the high-frequency band. The validity of the model is checked by comparison with the results of numerical simulation of single wire above ground plane, twowire, coaxial, and triaxial transmission lines in a wide range of parameter values: the frequency is varied from 10 kHz to 8 GHz, the length of the line is from 20 cm to 5 m, height of the line above the ground surface is from 2 mm to 100 mm, the ratio of the load capacitance (inductance) to the line capacitance (inductance) is from 10−40 to 104. Straight and piecewise-straight lines (both parallel and non-parallel to the ground plane) are considered during the validation.

The analytical model for radiation of a rectilinear uniform transmission line placed above a conducting screen is proposed. The model is intended for diagnostics (express analysis) of unintentional interference in large complexes of radio and electronic equipment. The model makes it possible to compute the envelopes of the amplitude-frequency characteristics for electric and magnetic fields in any spatial point above the screen. Single wire above ground plane, coaxial and triaxial lines with various grounding configurations are considered. The model is based on replacement of the complicated transmission line by an equivalent (in terms of the radiated field) single wire over ground plane. Correctness of the proposed model was verified by comparison with numerical simulation results in the frequency band from 10 kHz to 2 GHz for lines of length from 5 cm to 10 m with various load and source impedances, the line height above the ground plane was varied from the radius of the line to 5 m, the observation point position was up to 5 m away from the center of the line in arbitrary direction.

A worst-case model of the plane wave diffraction by the rectangular or circular aperture is proposed. The model is intended for EMC analysis in a frequency range from 1 Hz to 40 GHz, and it is based on combining the analytic solutions of the diffraction problem for low-frequency, resonance, and high-frequency ranges. The combining is carried out by the use of matching functions which define a contribution of each analytic solution. The correctness of the proposed model was checked by comparison with numerical solutions of the diffraction problem in a wide range of the parameters' values: ratio of the wavelength to the maximal dimension (diagonal or diameter) of the aperture is from 0.05 to 300; ratio of rectangular aperture sides is from 1 to 100; ratio of the distance (from the aperture center to the observation point located behind the screen at arbitrary position) to the maximal dimension of the aperture is from 0 to 1000.

The worst-case model of a wire radiation field intended for the analysis of spurious couplings in complexes of radio and electronic equipment has been developed. The model is based on dividing the wire into straight-line segments and considering forward and backward current waves in each segment. The solution for each current wave is interpreted as interference of fields radiated by equivalent point sources, and the envelope of the amplitude-frequency characteristic is found in the area of resonances. The correctness of the model is checked in a wide range of problem parameters values: the length of the wire ranges from 0.1 m to 10 m, the height of the wire above the ground plane ranges from 0.1 mm to 1 m, and the observation point position is up to 10 m away from the center of the wire in arbitrary direction.

A worst-case approach to development of nonlinear models for RF front-ends and components is proposed. This approach makes it possible to avoid the omission of nonlinear interference in process of the computer simulation, which is very important for EMC analysis. Based on the proposed approach, we developed a technique for synthesis of the models intended for the use in framework of the discrete nonlinear analysis technology. For validation of the developed technique, nonlinear behavioral model of a microwave amplifier was synthesized.

Capabilities of the nonlinearity-filter (Hammerstein) cascade for amplitude demodulator simulation at the system level are described. This behavioral model is then validated for the diode envelope demodulator notwithstanding that the model structure is not compliant with the physical description of the demodulator.

It is suggested to use the method of signal-to-interference ratio (SIR) estimation by the minimum of interference power in combination with the technique of discrete nonlinear analysis of radio receivers. The method of the interference power minimum is compared to the SIR estimation methods being used in the framework of the discrete nonlinear analysis (method of two iterations and frequency selection method) in terms of applicability and computational efficiency.