Artificial Neural Network (ANN) has achieved great success in many fields, such as image and voice recognition. Recently, ANN is also applied to solve inverse scattering problems, because of the advantages that it is able to produce estimation results in real time and without local minimum problems, compared to optimization techniques. However, in the problem of estimating the permittivity distribution of a layered medium from the information of incident and scattered waves, as the number of layers increases, the possible combinations of permittivity become enormous, making it difficult to train an ANN. On the other hand, the performance is not good enough when using ANN to recognize both the permittivity and thickness of each layer from the scattered wave information, because the scattered wave is affected by both of them. In this paper, we propose new data-preprocessing techniques to address these issues, and the ANN-based estimation obtained good accuracy even when the observed data include some noise.

In order to investigate the influence of charging cable arrangements on contact discharge waveforms, which is not specified in the IEC calibration environment of ESD generators, we measure contact discharge waveforms by using four different models of domestic and foreign ESD generators with test voltages of 4 kV and 8 kV, including two battery-powered models, under different arrangements of around a 2 m charging cable, and analyze their spectra to clarify the effect of the charging cable arrangements on the ringing. The result confirms from the measured waveforms and their spectral characteristics that the ringing tends to be suppressed in the calibration measurement of ESD generators when the charging cable is placed floating from the metal plane compared to when the cable is placed along the metal plane. To verify this finding, we show the reduction effect of the cable arrangement change on the ringing by an energy ratio (ER) of the difference waveform between the measured contact discharge waveform and the IEC specified waveform, which corresponds to the amount of ringing generation, to reveal that the calculated values of ER are definitely reduced for the floating charging cable arrangement. Furthermore, the input impedances of a 2 m long return current cable grounded at one end under different arrangements are measured to calculate the spectra of the contact discharge waveform derived from a simplified equivalent circuit based on the IEC standard in the Laplace domain of an ESD generator, which indicates that the floating cable arrangement is more effective in reducing the spectra at frequencies below 40 MHz.

To-achieve multi-band technology and MIMO (Multiple-Input and Multiple-Output) technology, technologies are needed to accommodate multiple frequency bands in the radio section to make the equipment more flexible and compact. Particularly, many studies have been conducted to use an 1-bit ADC (Analog to Digital Converter) for miniaturization^(4)-(11). There have been many reports on research using Dithering technology⁽²⁴⁾ and an 1-bit ADCs that apply the phenomenon of stochastic resonance in recent years⁽²⁵⁾, and the similarity between Dithering technology and stochastic resonance has also been reported⁽²³⁾. An 1-bit ADC using the Dithering technique does not require complex circuits like a Delta-Sigma ADC⁽¹⁷⁾, so it can be implemented with a simpler configuration than a Delta-Sigma ADC and can be downsized when implemented in hardware. However, when used as a receiver, nonlinear distortion of the received signal due to the nonlinearity of the 1-bit ADC is a problem.

Therefore, this paper proposes a method of mitigating the effects of nonlinear distortion caused by an 1-bit ADC by using blind nonlinear compensation in a wideband modulated receiver composed of an 1-bit ADC using Dithering technology. Compensation techniques used to compensate for distortion caused by nonlinearities in nonlinear amplifiers are applied^(12)-(16), and the effect of the improvement is evaluated in terms of the EVM (Error Vector Magnitude) of the signal after reception. We report that the proposed method suppresses the characteristic degradation affected by nonlinear distortion caused by an 1-bit ADC, and that EVM can be reduced by computer simulation.