Maciej Surma

Efficient wideband analysis of electromagnetic scattering and radiation problems

In this paper, single point and two point asymptotic waveform evaluation (AWE) are outlined as the efficient techniques for obtaining broadband response of wire radiators/scatterers from the method-of-moments (MoM) samples generated for a few isolated frequencies. An adaptive scheme, based on two-point AWE technique, is suggested for optimal choice of the location of the expansion points. Sample numerical results for two practical structures are given. The approach presented in the paper gives good accuracy and speed-up ratio for wideband analysis.

Immunity of medical electrical equipment to radiated RF disturbances

Immunity of medical equipment to radiated radio frequency (RF) electromagnetic (EM) fields is a priority issue owing to the functions that the equipment is intended to perform. This is reflected in increasingly stringent normative requirements that medical electrical equipment has to conform to. A new version of the standard concerning electromagnetic compatibility of medical electrical equipment IEC 60601-1-2:2014 has recently been published. The paper discusses major changes introduced in this edition of the standard. The changes comprise more rigorous immunity requirements for medical equipment as regards radiated RF EM fields and a new requirement for testing the immunity of medical electrical equipment to disturbances coming from digital radio communication systems. Further on, the paper presents two typical designs of the input block: involving a multi-level filtering and amplification circuit and including a solution which integrates an input amplifier and an analog-to-digital converter in one circuit. Regardless of the applied solution, presence of electromagnetic disturbances in the input block leads to demodulation of the disturbance signal envelope. The article elaborates on mechanisms of amplitude detection occurring in such cases. Electromagnetic interferences penetration from the amplifier’s input to the output is also described in the paper. If the aforementioned phenomena are taken into account, engineers will be able to develop a more conscious approach towards the issue of immunity to RF EM fields in the process of designing input circuits in medical electrical equipment.

Design of dual-polarized MIMO linear antenna arrays with increased port-to-port isolation

In the paper selected issues of feeding networks for dual-polarized linear antenna arrays designed for 2×2 MIMO applications are described. The influence of topology of corporate feeding network on achieved port-to-port isolation is shown as the result of computer simulations. As an example, four element linear arrays of two-layer electromagnetically coupled microstrip antennas designed for U-NII 5.15-5.85 GHz frequency band are examined in CST Microwave Studio.

Combination of structure decomposition technique and impedance matrix interpolation for efficient wideband analysis based on method of moments

In this paper, the combination of structure decomposition method and impedance matrix interpolation technique is presented. This approach allows to reduce the time of wide band analysis of while maintaining good accuracy of the results comparing to the results obtained via direct method of moments.

Efficient Method for Obtaining Derivatives of Current Vector for AWE Techniques

In this paper, the improved asymptotic waveform evaluation (AWE) are outlined as the efficient, based on method-of-moments, technique for obtaining broad-band response of the radiators/scatterers. The proposed approach allows to make conventional AWE techniques more effective with respect to time of analysis and memory requirements. The technique consists in fast algorithm for evaluation of impedance matrix derivatives and current vector derivatives, i.e. the most important elements for AWE technique.

Time and space evolution of electromagnetic field radiated and scattered by wire structures

In this paper attention is focused on visualization and animation of the time and space evaluation of electromagnetic fields radiated and scattered by, simple, wire structures under pulse excitation. For obtaining distribution of electromagnetic fields, FDTD technique was employed. For visualization and animation the numerical results, Mathematica of the Wolfram Research and PowerPoint were employed, respectively. That kind of representation of the results may be very helpful for understanding transient electromagnetic phenomena.