Hong-Sik Keum

Analysis and verification for errors of normalized site attenuation method below 30 MHz

Various electrical devices, which radiate electromagnetic Helds of frequency ranges below 30 MHz, such as wireless power transfer systems, wireless charging devices, and PDP TVs, have been widely developed and manufactured. These devices radiate the spurious emissions of low frequency bands, below 30 MHz, and could affect other devices. In response to this, IEC CISPR has been discussing and standardizing the measurement and validation methods below 30 MHz. In addition, researchers who attended the CISPR annual meeting suggested the normalized site attenuation (NSA) method. However, this method has several problems in terms of the antenna factors, antenna feeding point, NSA values, etc. We found the NSA values and antenna factors to be the most important problem when the test is repeatedly performed. We need to recalculate the NSA values according to exact antenna shape and where the antenna feed point is. Therefore, we recalculated and adopted new NSA values by using the NEC program. According to the site validation test results, the calculated site attenuation deviation is satisfied within 4 dB ranges.

Unintentional radiation of electromagnetic waves caused by deterioration of metal halide lamps

In this paper, unintentional radiation from damaged metal-halide lamps was measured and analyzed through the EMC measurement and Amplitude Probability Distribution (APD) measurement. The noise caused by glow or arc discharge shows characteristics of impulse. The unintentional noise exceeds the standard limits of radiation emission and conducted emission in CISPR 15 and the results are up to 49.06 dBuV/m and 47.8 dBuV, respectively. Due to the instability, frequency characteristics of the noise were not measured accurately. The frequency characteristics of impulse noise were measured with APD. The results show that 94.2 % of electromagnetic radiation of over 60 dBuV/m was converged ranging from 30 MHz to 200 MHz.

Reactance Set and Performance Evaluation of Chaos QPSK Beamspace MIMO System Using ESPAR Antenna

Recently, researches about MIMO(Multi-Input Multi-Output) system are being studied actively due to high-capacity and high-speed communication. However, MIMO system has many RF(Radio Frequency) chains according to many array antennas. So, MIMO system has disadvantages such as high-complexity and high-power-consumption. Also, it is impossible to miniaturize the antenna dimension. In order to solve these problems, beamspace MIMO system using ESPAR(Electronically Steerable Parasitic Array Radiator) antenna was proposed. It is possible to reduce the complexity and the power-consumption, because it has single RF chain by using one active antenna and several parasitic elements. In this paper, in order to improve the security, for the first time, chaos communication algorithm is applied to QPSK modulated beamspace MIMO system using ESPAR antenna. We define as chaos QPSK beamspace MIMO system, and evaluate the SER performance. Also, we confirm that QPSK symbols can be made by changing the reactance values of parasitic elements, and evaluate the SER performance of this system.