Zhou Feng

Intrinsic Characterization of Human Metal ESD: Current, Electromagnetic Field and Displacement Current

This paper advances an electrostatic discharge displacement current (ESDDC) which will flow through the space to all the victim devices on the EUT when discharge occurs and the ESDDC contributes to the failure of the equipment besides the discharge current and the electromagnetic field radiated from the ESD. Experiments were performed to test the ESDDC. The results show that the ESDDC is one of the major characters of the electrostatic discharge

ESD Generator Analyzed by Transmission Line Theory

In this paper, the transmission line theory was used to analyze the electrostatic discharge (ESD) transient process. Finite-difference time-domain (FDTD) method is used to simulate the discharge current being prescribed in the IEC 61000-4-2. The factors influencing the current parameters were examined, the suggestion for designing ESD generator was put forward

Distance boundary of antenna isolation calculation in engineering

When wireless base station antennas share a tower or site, the electromagnetic compatibility should be considered, one of which is to calculate the antenna isolation. For horizontal isolation, calculation is based on antenna pattern and the traditional far-field boundary is d>2D2/λ. In practical scenarios of antenna co-site, however, antenna distance cannot fit these boundary conditions. Regarding this issue, Magnitude Error on Sphere (MES) is defined as a new indicator of antenna far-field and near-field approach degree. The analysis has shown that the distance boundary in horizontal isolation calculation can be set as d>8λ for typical base station antenna structure. While for vertical isolation calculated by Iv(dB)=28+401g(d/λ), the distance boundary can be set as d >4λ.

The optimized polarization for indoor MIMO based on cross polarization loss and near earth loss

As has been shown by our testing, the propagation loss (PL) of vertically-polarized (VP) transmitting and horizontally-polarized (HP) receiving is larger than that of VP transmitting and VP receiving, i.e. the cross polarization loss exists. At wireless covered indoor situation, the PL of HP waves is different with that of VP waves, and the difference is traditionally described as near-earth loss. Consider the cross-polarization loss and near earth loss, a 2×2 orthogonal dual-polarization MIMO system has a total receiving power irrelevant of the polarized angle settings, but the balance of the receiving power is dependent on the angle settings. When the receiving setting is +45°/-45° dual-polarization, the two antennas receive equal power, which reaches equilibrium.

Frequency spectrum of signal sampled in modulation domain

There is complete sampling theory in time domain and frequency domain, sampling in the modulation domain is a new interesting topic. Mathematical analysis and simulation based on FSK signals reveal the rule: If we sample a signal in the modulation domain with rate fms, the frequency spectrum will extend periodically at the interval fms, which means harmonics will appear. And further measurement validates the rule. The rule will help to construct a more complete sampling theory contain time domain, frequency domain and modulation domain.

ESD Immunity Test and Several Improvements for Digital Electronic Dictionary

Electronic devices are getting more and more sensitive to the electro-static discharge (ESD) because of their smaller size and higher frequency. An electronic dictionary device studied here has failed in the ESD immunity test according to the IEC61000-4-2 standard. Many factors which could impact on the ESD immunity performance of the device are investigated in the test and some suggestions are also given in this paper for improving its performance. The improving suggestions are listed and analyzed combining the device in detail in this paper: 1) improving the ESD immunity performance of the dictionarys PCB; 2) changing the outer package material for the dictionary, protecting the LED; and 3) building a complete ESD test system. The device has gained a significant improvement on the ESD immunity by using merely part of our suggestions. We hope that this could be a reference to the manufactures of similar devices as well