• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.657-662
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• 2008

Inter-radar interferences may cause the critical impact to the radar detection performance because radar operates with high power and wideband. In this paper, the international criteria for radar interference protection is reviewed based on the ITU-R recommendation, and the radar interference analysis model is presented by taking into account the radar operating environments such as ground, airborne and spaceborne radars. Finally, the simulation results are presented with the interference Impact analysis in various radar environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.28-31
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• 2018

This paper investigates the ground reflection effect on the channel capacity of an orbital angular momentum (OAM) multi-mode transmission system that uses uniform circular array (UCA) antennas. The ground-reflected signals cause inter-mode interferences between the OAM modes, and lead to system performance degradation. The OAM multi-mode channel capacity severely degrades owing to the ground reflection as the transmission distance increases. Increasing the UCA height above the ground and using highly directive array elements can mitigate the ground reflection effect and increase the channel capacity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.883-889
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• 2009

Since the SRRs(Short Range Radar) load on the GVESs(Ground Vehicle Equipment System) are operated within several hundred meters, it is important to suppress the interferences between the SRRs. These interference are reduced using the frequency separation between channels, however this method isn't a perfect solution owing to a difficulty of a realization for the interference suppression. Thus, a pulse-to-pulse coding used to suppress the interference fundamentally is proposed in this paper. The concept, the application method and the test results of the proposed method have been described in this paper.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.182-188
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• 2005

This paper presents an efficient technique for interference suppression in IEEE 802.11b WLAN systems. A linearly constrained adaptive array processor which may improve reception performance of WLAN device by reducing co-channel interference signal and multipath effects effectively was proposed. A spatial smoothing method is used to prevent cancellation of a desired signal in a coherent environment and also integral nulling method is employed to improve the array performance in indoor environment. It was shown that the integral nulling approach performed best while the spatial smoothing method performed better than linearly constrained array processing. The performance of the WLAN system may be improved by the proposed methods which reduce co-channel, coherent, and WPAN interferences effectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.694-704
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• 2001

In this work, We evaluate the performance of eigencanceller which can suppress directional interferences and noise effectively while maintaining specified beam pattern constraints. The constraints and optimal weight vector of eigencanceller vary by using interference and noise or desired signal, interference and noise as array input signal. From the analysis results in the steady state, We show that weight vectors in each case are simplified the form of projection equation that belongs to desired subspace orthogonal to interference subspace and eigencanceller has the better performance than DMI method through mathematical analysis and simulation.

• Journal of electromagnetic engineering and science
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• v.6 no.3
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• pp.189-195
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• 2006

In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 GHz system, with the space diversity of 25 m distance between antennas or the frequency diversity of ${\Delta}f/f=0.05$, under 64-QAM and 60 km at BER $10^{-6}$, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to - 5.9 dB or from 6.0 to - 4.3 dB for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.534-543
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• 2000

In this paper, when the current optical communication system is used for the DWDM. The FBG filter for the DWDN is able to reduce the interferences between the adjacent channels. In this paper, therefore, we find the relection spectrums for the three types of induced index changes, that is, uniform, Gaussian apodized, and raised-cosine apodized. From the obtained result in this paper, we can see that uniform FBG does not fit, and that the smaller the maximum induced index change $\sigma$ is and the larger the value of parameter C in the raised-cosine apodized FBG and G in the Gaussian apodized FBG are the fitter they are on the narrow filter for DWDM.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.164-170
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• 2010

For the surge currents like lightning or ground fault currents containing high frequency components which cause the electromagnetic interferences for the electronic devices and communication equipment, the grounding impedances give the significantly composite characteristics which are dependent on the frequency of surge currents. In this paper, the analytical model and method for determining the optimal length of the newly developed coaxial type carbon ground electrode which has a little fluctuation in grounding impedance with frequency. The length of minimizing the fluctuation of grounding impedance by changing frequency from 100[Hz] to 1[MHz] was determined, and the validity of this proposed method was confirmed by comparing with the simulated and measured data.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1063-1064
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• 2008

Bimodal tram has a carbody made of polymer composite material which is good electrical insulator. As an series hybrid type, Alternating voltage generated from generator coupled with CNG engine are rectified and transformed to variable voltage ranges which are applied to electrical apparatus and ECUs equipped inside of the tram. The failures of electrical insulation between high voltage($400V{\sim}800V$) and low voltage(24V) or between different kind of voltages such as AC and DC may cause some electrical interferences to prevent from operating rightly and other safety problem. This paper have investigated about the degradation factors of the electrical insulation and the earthing method available to bimodal tram, which is effective for preventing the electromagnetic interference coming from the inside or outside of tram but need some detecting measurements of earth leakage through electrical systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.365-371
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• 2014

It is essential for the combined military weapon system to be equipped with interoperability for the efficient combat operation in the modern warfare environment. Since most of modern military systems utilize the electromagnetic wave for the radio communication in the network-centric warfare system, they can be vulnerable to the mutual interference among the adjacent combined military systems. In this paper, the typical radio communication systems are modeled with the modulation types of both spread and non-spread spectrum system. The various interference signals were generated for the simulation of the mutual interference influence from the adjacent radar and communication systems. The simulation results show that the detection performance of the victim communication receiver is seriously affected by the various interferences such as the types of modulation and the ratio of the overlapping bandwidth of the adjacent interferers. This result will be useful for defining the criteria of the interference protection in the combined military system for the interoperability in the future.