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A mode division multiplex transmission system that assigns signals to the eigenmodes of a transmission line was proposed for a cable that is uniform in the longitudinal direction. The transmission characteristics when the proposed method is used in a 1m long shielded untwisted 4-wire cable were verified by circuit simulation. It is shown that the proposed method enables four-channel simultaneous transmission. In addition, the proposed method significantly improves the crosstalk compared to the differential and single-ended transmission methods.

Radiated emission from shielded twisted pair (STP) cable was calculated using a chain-parameter-matrix. The series connection of the matrix represented the transmission line inside the shield, and the common-mode (CM) current was obtained by solving the matrix equation. The induction voltage on the outside of the shield was determined from the CM current using the shield’s transfer impedance. The current on the outside of the shield was calculated from this induction voltage. And then, the radiated electric field was calculated from this current. The matrix elements representing the transmission line between conductors and shield were determined from the measurement, and the transfer impedance was also determined from the measurement. The line constants between shield and ground were determined from the theory by assuming the shield as a copper rod. The maximum current on the outside of the shield and the maximum radiated electric field were measured in the frequency range from 30 MHz to 300 MHz, and these were compared to the calculated value. The calculation results of the maximum current intensity were well agreed with the measured value, and the calculation results of the maximum radiated electric-field strength were almost agreed with the measured value.

In this article, we introduce an alternative terminating condition for the AC mains cable of Equipment Under Test (EUT) with appropriate common mode impedance by VHF-LISN in radiated emission measurements at test sites. In Round Robin Testing (RRT) conducted by CISPR SC-A/I joint ad hoc group 6 (JAHG6), inter-laboratory reproducibility was significantly improved by setting terminating conditions for the AC mains cable of EUT, thus, reflecting the same results as those of previous RRT conducted by CISPR/SC-I. However, since only a conventional comb generator was employed, differences in radiated emission of EUT with and without AC mains cable termination by VHF-LISN were not clear. In this RRT, we performed actual product measurement (prepared by ten participating laboratories) and compared the accumulative probability distributions of radiated emissions by using two types of VHF-LISN of different termination impedances and without a termination device (deemed as the actual operating condition). From the investigation results, mains cable termination with VHF-LISN of a specific common mode impedance was deemed to be valid for radiated emission measurement.

The radiated emission of the power line communication (PLC) system should be investigated to maintain electromagnetic compatibility. Recently, the development of applying the PLC system to factories and offices was started. In these environments, many cables are arranged in the cable tray. Therefore, the multi-cable effect should be investigated. In this paper, the multi-cable effect was examined by using the scale model. The 0.5 times scale model was constructed in the semi-anechoic chamber, and the maximum common-mode (CM) current was measured by changing position along with the cable. The measured result was agreed with the result using the full-size original model. The experiment by using five cables suggested that the influence by the conductive loss and the dielectric loss of cable was not large for the maximum CM current, and the CM current was dominated by the cancellation effect of the in-phase currents flowing on the cables. The investigation for dependency of the position of the signal apply was indicated that the effect can be roughly estimated from the current division factor.

Reproducibility of radiated disturbance measurements is influenced by the line impedance of the power source used for EUT. A VHF-LISN was proposed to solve this issue. A VHF-LISN can define line impedance so as to avoid such influences caused by different line impedances for connection points at different test sites. At present, two proposed types of VHF-LISN - balanced termination and unbalanced termination - are being considered for implementation in CISPR 16 basic measurement standards. Round robin testing was conducted to investigate the effectiveness of improving reproducibility of radiated emission measurement with two types of VHF-LISN, using a versatile comb generator having two signal source modes, common mode (CM) and differential mode (DM), and by using both 2-wire and 3-wire AC mains cable respectively. CMAD termination was provided as an option. The testing concluded that reproducibility between test sites was improved by VHF-LISN termination for both CM and DM emission sources with CMAD termination effectiveness proving to be limited in the case of 2-wire mains cable being used in CM signal source measurements.

In this paper, reduction effect of a common-mode filter is discussed. When the performance of a common-mode filter is evaluated, it is necessary to consider not only S CC21 but also S CD21 . Using these two parameters, the common-mode current flowing on the secondary side of the common-mode filter was formulated. Common-mode current is a summation of two causes: common-mode transmission and differential mode conversion from a signal source. The common-mode current depends on not only the phase relationship between S CC21 and S CD21 of the common-mode filter but also the phase relationship between the differential mode and the common mode of the signal source. Even if the same common-mode filter is used on a differential signaling system, the common-mode current increases or decreases depending on the phase of the differential mode voltage and the common-mode voltage at the signal source.

Power line communication (PLC) is the technology that uses a power line as a signal line. Because an imbalance of the power line is generally larger than that of the communication line, we should take care of radiated emission from the PLC cable. A small-scale model can be applied to evaluate easily the radiated emission from PLC cables for large structures. In a scale model, all structures in the PLC system need to be manufactured as 1/n size to satisfy complete equivalence between the reference model and its scale model, though it is difficult to fabricate the fine structure such as conductors in a cable smaller. Therefore we investigated the effect on common-mode current when some parameters of the scale model were not scaled down perfectly. As a result, a reliable scale model was obtained to evaluate peak common-mode currents in resonant frequency even if some parameters of the structure were incompletely scaled. Furthermore, the cable length dependency of common-mode current was evaluated experimentally by using the scale model.

The common-mode filter (CMF) is a key device for suppressing emissions radiated from telecommunication cables. Recent serial interfaces deliver the necessity of considering that common-mode (CM) disturbances are converted from the differential mode (DM) telecommunication signals by a CMF. To examine this phenomenon, this study investigated the $S_{\text{cd}21}$ characteristic, which is one of the mixed-mode S-parameters. Two types of CMFs whose $S_{\text{cd}21}$ were different were examined. A signal was supplied to an unshielded twisted pair (UTP) cable through the CMF. The emission from the cable was measured using a setup complying with CISPR 25. Then, the relationship between the ratio of CM to DM signals and the emission level was investigated. The results showed that the emission level decreased as a result of employing the lower $S_{\text{cd}21}$ CMF and that the emission level was linearly proportional to the ratio of the CM to DM signals. The results indicate that ${S}_{\text{cd}21}$ is an essential parameter with which to evaluate CMFs used in telecommunication ports of serial interfaces.

In this article, we investigated the influence on radiated emission characteristics in the condition that an mains cable of equipment under test (EUT) leaving from test area was terminated by balanced and unbalanced type common mode impedance stabilization devices. To investigate the influence by the same termination condition of mains cable, we performed the simulation analysis on radiated emission characteristics of the product with 3 wires (3W) mains cable which has a protective earth (PE) line and a product with 2 wires (2W) mains cable which has no PE line. With regard to this analysis, we conducted also the actual measurements with two types of mains cable by using a comb generator. From these results, we were able to estimate that the radiated emission from the products having 3W mains cable were became from 3 to 5 dB lower at a VHF band than the product having 2W mains cable. Furthermore, we investigated the influence on radiated emission characteristics by two terminating conditions when EUT setups including cable arrangement were changed. As a result, there was no difference compared with the maximum standard deviation of without device. This means it is insufficient only by establishing the termination condition of mains cable.

The differential mode impedance (DMZ) and the longitudinal conversion loss (LCL) are important parameters to introduce high-speed power line communication (PLC) systems. Therefore, we should evaluate the DMZ and LCL in a factory environment because the three-phase power distribution system has been employed in factories. The admittance matrix elements at the power distribution board were determined from S-parameter measured with a vector network analyzer. An isolation probe was developed to measure S-parameters under high voltage applying conditions. Measurements were carried out at 60 points in 4 factories. The admittance matrix was represented by the equivalent circuit composed by six impedances, then the DMZ and the LCL were calculated from the mean value of the impedances. The results showed that the absolute value of DMZ was lower than the characteristic impedance of the PLC transmission line, and the LCL value was similar to the LCL in house environment where a two-phase power distribution system was employed.

To improve the reproducibility of radiated emission measurement, a very high frequency line impedance stabilization network (VHF-LISN) has been proposed and has been under consideration for standardization into basic measurement standards (CISPR 16-2-3 and CISPR 16-1-4). Since a VHF-LISN can be placed on the ground plane (GP), we thought it was necessary to investigate the effects of placing it. Initially, the effects were investigated by normalized site attenuation (NSA) measurements. The influence of a common-mode absorbing device (CMAD) and an artificial mains network (AMN) were also investigated in the same way for comparison. Then, we created simulation models of antennas and these devices. Both actual measurement results and simulation results demonstrated that the influence of VHF-LISN was smaller than the influence of CMAD or AMN. The results suggest that evaluation of the influence on the NSA of a VHF-LISN placed on the GP is not needed if the evaluation is not required for a CMAD or an AMN.

Characteristics of radiated emission from the three-wire power cable where the power line communication signal was transmitting was studied by using circuit theory. The simple model whose length was 14.4m was used for the investigation, and the radiated emission was calculated and measured. The average deviation between the calculated data and the measured data was -3.6dB and the standard deviation was 3.3dB. The calculation results indicated that the maximum magnetic field strength could be estimated from the maximum common-mode current. The analysis also suggested that the maximum common-mode current of a three-wire cable was less than that of a two-wire cable in many cases.

Electromagnetic field radiated from Power Line Communication (PLC) which was applied to three wires system was examined with Method of Moments (MoM). The influence of the wire configuration and the terminating condition of the third wire was also evaluated. Calculated common mode current and electromagnetic field intensity agreed well with measured results. The calculation results showed that electromagnetic field intensity decreased or didn't change from two wires system when the third wire was connected to the ground.

To improve the correlation of radiated emission measurements between test sites, a very high frequency line impedance stabilization network (VHF -LISN), a coupling/decoupling network for emission measurement of mains (CDNE-M), and a common-mode absorbing device (CMAD) were proposed as the devices that improve inter-site correlation. The result of the international round robin testing (RRT) using two pieces of equipment under test (EUT) has verified an inter-site correlation improvement effect of both EUTs in VHF-LISN and CDNE-M, but the effect varies depending on EUTs in CMAD. As an additional verification of the previous international RRT, we investigated why the effect of VHF-LISN and CMAD was different. Initially, we evaluated the relation between the influence on the common-mode current variation and the impedance value inserted into the protective earth (PE) line by using a CMAD and an artificial EUT. The evaluation result demonstrated that, if the PE line current was reduced by inserting the impedance, the influence due to changes in the termination impedance at the outlet decreases. Based on this result, we evaluated the effects of improvement in inter-site correlation of VHF-LISN and CMAD by changing the PE line current for three piece of EUT. The evaluation result demonstrated that an effect of VHF-LISN did not depended on the PE current, but, in the case of CMAD, almost no effect was gained when the sufficient PE current existed. Because a PE line is directly connected to the frame of EUT in many cases, this result indicates that the device that defines termination impedance at the outlet on the turntable, such as VHF -LISN, is required to improve the inter-site correlation.

The international round robin test (RRT) demonstrated that the site correlation improvement effect of a common-mode absorbing device (CMAD) varies depending on the equipment under test (EUT). This paper investigates the cause. The standard deviation of the common-mode current, when the termination condition was changed at the AC mains cable end, was obtained from the calculation by using 6-port network and the measurement by using the artificial EUT. The results indicated that the standard deviation was reduced when a high impedance was inserted between the EUT's frame and the protective earth (PE) wire. The results, based on the EUT used in RRT, indicated that the standard deviation of radiated emission was reduced by decoupling the PE wire from the frame. In conclusion, since the EUT's frame is directly connected to the PE wire in many cases, the effect of CMAD can be discounted.

This paper verifies the degree of influence that the standardization of mains cable termination condition which is currently proposed with CISPR/SC-I gives to the Standards Compliance Uncertainty (SCU). First of all, we presumed the uncertainty value of the mains cable termination in the radiating emission measurement from the results of Round Robin Test which circulated the same EUT, the same cable termination device, and the same mains cable layout. And then, the radiating emission levels which were calculated considering with the tolerance of the termination impedance were used for presuming the measurement uncertainty when the mains cable was terminated by the device. Finally, the expanded Measurement Instrumentation Uncertainty (MIU) including the uncertainty by AC mains cable terminating condition was considered in calculation. From this result we have proposed this condition shall be included to the MIU.

In regard to the influence of AC mains cable termination on radiated emission, we compared and analyzed the simulation results in single-wire and 3-wire line configuration by round-robin testing with a comb generator and tower PC. The analysis result demonstrates that the deviation with 25-ohm and 150-ohm termination and the deviation with a comb generator and a tower PC using a very high frequency line impedance stabilization network (VHF-LISN) and coupling/decoupling network (CDNE) are nearly equal. Thus, single-wire simulation reflects the result using a comb generator in RRT, and 3-wire simulation reflects the result using a tower PC. Based on these findings, we compared deviations of average values of radiated field strength of the comb generator and tower PC by VHF-LISN and CDNE, with based on “without termination device.” We thereby conclude that the terminating each line with 50 Ω by VHF-LISN is the proper way.

In the emission standard CISPR32 for multimedia equipment (MME), the specification provided for cabling on the reference ground plane (RGP) stipulates that the thickness of the insulation shall not be more than 150 mm. However, the emission standard does not specify a minimum insulation thickness. Therefore, it is assumed that measurements will be conducted at various insulation thicknesses across various test sites. Thus, the cable impedance varies with the degree of coupling with the RGP, which may significantly degrade the reproducibility of measurements. This investigation verifies that varying insulation thickness does impact AC cable-radiated emission. A very high frequency Une impedance stabilization network (VHF-LISN) representing the common-mode impedance of an AC outlet supplying power to the equipment under test (EUT) in the actual test site was used. The test results have verified that the radiated emission changes much at an insulation thickness of 2 mm or less and the change gradually decreases as the thickness increases (5 dB or less at a thickness of 12 mm or more and 2 dB or less at a thickness of 30 mm).

In radiated emission measurements, the radiated disturbance from the AC mains cable leaving the equipment under test (EUT) significantly differs with the termination condition of the AC mains cable. Because this condition was not defined in applicable test standards, VCCI developed a device called the very high frequency line impedance stabilization network (VHF-LISN) that controls the termination impedance at the end of the power line in the test site connecting the AC mains cable of the EUT. Since then, VCCI has verified the effectiveness of VHF-LISN in the reproducibility of radiated emission measurements in semi anechoic chambers (SACs) while making proposals to CISPR, leading to discussions on the conditioning of the AC mains cable termination currently under way in CISPR SC-I/WG2. Now, VCCI has completed a new series of tests on the VHF-LISN in a fully anechoic room (FAR) according to the test method adopted in CISPR 32 Edition 2.0. This paper reports the results of these new tests and concludes that the reproducibility of radiated emission measurements in the FAR is also verified to improve significantly by controlling the termination condition of the AC mains cable through the use of VHF-LISN.

Method of modeling electronic equipment by using current sources was applied to the estimation of far electric field strength and the evaluation of the disturbance source position. In this paper, we investigate the validity of the modeling method where the current source positions are fixed because the model is useful to the numerical calculation. Five kinds of equipment were used for the investigation. The radiated electric field strength around the equipment was measured in full anechoic room (FAR) and the amplitude and phase of the current source were determined by solving least squares problem. The source position of 14 was used for the investigation. The results showed that the deviation from the measured value to the calculation value is almost within 2dB. The obtained equipment models were applied to investigate the influence of biconi-log antenna. The deviation from a half-wave dipole antenna to a biconi-log antenna was investigated in case of a half-wave dipole antenna and the equipment source model. The results showed the deviation of the equipment model was larger than the deviation of the half-wave dipole antenna. This means that the equipment model is effective to evaluate the larger than the deviation of the half-wave dipole antenna.

At present, power supply impedance of radiated emission measurement site is not specified in any testing standards. In measurement of radiated emission from desktop equipment, noise emitted from power line of the EUT is a factor that worsens site correlations because the noise varies with the impedance between power line and the ground. Under such circumstances, VCCI developed VHF-LISN to stabilize power supply facilities for the purpose of improving the reproducibility of radiated emission measurement. To assess its effectiveness, an international inter-laboratory comparison program was carried out, provided with EUTs and termination control devices including the VHF-LISN to ensure identical setup across sites. Until February 2014, this international program was promoted at 16 sites in 9 countries. From the final results, we conclude that the VHF-LISN is the best device to improve the reproducibility of radiated emission measurement.

Capacitive Voltage Probe (CVP) is used for measuring disturbances at telecommunication ports. The sensitivity of CVP changes by type of cable. Therefore, the pre-calibration is needed for every type of cable before measurement. The method of changing the input capacitance was proposed in order to avoid the pre-calibration. However, the accuracy of sensitivity was not sufficient. This paper proposes the method of improving the accuracy. The input capacitance was changed by a mechanical relay, and the output level difference was measured by a network analyser or a lock-in amplifier. The regression line parameters were obtained from the investigation which used many type of cable. The investigation showed that the deviation between the estimation value using the regression line and the measurement value is within 1dB. By using actual equipment, the disturbance level was measured and they were compared to the measured value by ISN. The results showed that the average deviation was within 1dB.

Telecommunications signal emissions from unshielded twisted pair (UTP) cable should be suppressed to maintain EMC of telecommunication systems. This paper describes the suppression effects of the ferrite cores which are installed on the UTP cable. Twisted pair wire with ferrite core was modeled by 4-port network to evaluate suppression effect. Parameters of the networks which are constructed with UTP cable or ferrite core with wires were determined from calculation and measurement. Using the networks, the common-mode current distribution on the cable was obtained, and emitted electric field strength was calculated from the distribution. The emission suppression effect was obtained from the result, and the results were almost agreed with measured value. The calculation results suggest that 1) the ferrite cores should be arranged side by side, 2) these should be placed near the signal supply end of the cable., 2003 IEEE Symposium on Electromagnetic Compatibility, August 18-22, 2003, Boston, MA, USA

A method of evaluating the isolation factor from an AC mains port to a telecommunication port was investigated. Telecommunication equipment was represented by a 4-port network consisting of a pair of wire and ground. The relationship between input and output signals of the network was represented by an F-matrix and the isolation factor (ratio of input to output signals) was derived from the matrix. We developed a method of measuring the parameters and the measured values for a resistance-network agree well with calculated ones. The evaluation results of the isolation factor for three types of telecommunication equipment show that isolation for differential-mode noise from AC mains to telecommunication ports is larger than that for common-mode noise., 2003 IEEE Symposium on Electromagnetic Compatibility, August 18-22, 2003, Boston

The method of stabilizing termination impedance at AC cables is discussed to improve the reproducibility of test results between test sites. The common-mode absorbing device (CMAD) and the VHF band line impedance stabilization network (VHF-LISN) were investigated as the devices which can stabilize the termination impedance, and the investigation indicated that the deviation between test sites depended on the type of equipment when CMAD was used as the device. The phenomenon was studied by connecting the artificial network (AN) to the AC cable end. Comb generator and PC were used for the study as EUT. The termination impedance of the AC cable was changed by the AN, and then, the radiated electric field strength and the common-mode current were measured. The investigation indicated that the standard deviation of the field strength is similar to that of the common-mode current. The AC cable with CMAD and the AN were presented by an equivalent circuit, and the circuit parameters were determined from the measurement value of S-parameters. The equivalent circuit and disturbance sources of EUT were determined from the measured currents intensity and S-parameters. The common-mode current was calculated when the termination impedance of the AC cable was changed, and the standard deviation of the common-mode current was estimated. The comparison with the measurement value showed that the type of EUT influenced the deviation between test sites.

Lightning surges in a telecommunication building were observed before and after installing a dissipation array system (DAS) for lightning in winter. A portable digitizing oscilloscope and a multichannel digitizing oscilloscope with an optical fiber system were used for the observation. The observed results from winter 1991 to winter 1996 show that the peak value occurrence probability at an antenna tower leg was not changed before and after installing the DAS and the occurrence at a pillar of the building was decreased a bit by installing the DAS. The peak value of the lightning current at the lightning rod of the building was estimated from the surges observed at the lightning rods, at a leg of each telecommunication tower, and at a building pillar. The occurrence calculated from this value was almost the same before and after installing the DAS., 1998 International Symposium on Electromagnetic Compatibility, 24-28 August, 1998, Denver, CO, USA

VCCI had started Kit Module Program in 2005 in order to control EMI of the modules. In this program, the electric current on the power line (PL) of the power distribution network (PDN) on the printed circuit board (PCB) is measured by the magnetic probe (MP) method which has been standardized by IEC for the EMI testing of LSI. In this paper, the test result of several kinds of module is presented. They were tested by the measurement method of Kit Module Program and by the measurement method of the radiated emission (RE) complying with IEC/CISPR22. As the result, it was clarified that the MP method is suitable for the test of the module. Although the compatibility with the current EMI test method of VCCI exists as the problem, Kit Module Program will offer the simple and convenient management method to the manufacturers of the module and IT equipment (ITE).

In recent years, personal computers have been constructed by combining modules such as a hard disc drive and memory boards. Although a simple method for measuring disturbances from such modules in the frequency range below 1 GHz has been proposed, device technology progress needs an evaluation method above 1 GHz. This paper describes a method using a magnetic probe for measuring disturbances in the range from 1 GHz to 6 GHz. A test board for use above 1 GHz was developed according to the specifications for use below 1 GHz, and the current distribution and decoupling characteristics were evaluated. The results show that the decoupling factor was less than −11 dB and the maximum current appeared at the nearest point to the decoupling capacitors. Analysis by the finite difference time domain (FDTD) method indicates that the calculated current distribution agrees well with the measured value and that the maximum current could be measured at the nearest point to the decoupling capacitors. Measurement results for a hard disc drive with a USB3.0 port indicate that the disturbance level could be measured at the nearest point to the decoupling capacitor.

This paper describes a method of improving the frequency response of an electric field sensor. A modified LiNbO/sub 3/ substrate shape reduces the sensitivity deviation from 4 [dB] to 1 [dB] and the maximum operating frequency is raised from 300 [MHz] to 1 [GHz] by using a resistive loaded element., 1994 IEEE Instrumentation and Measurement Technology Conference, May 10-12, 1994, Grand Hotel Hamamatsu, Hamamatsu, Japan

The effect that disturbances from electrical equipment have on a digital TV signal was evaluated using an actual broadcasting signal. Various types of disturbance from equipment were measured by an oscilloscope and then the measured waveforms were generated by an arbitrary waveform generator. The TV signal and the disturbance level were evaluated using the quasi-peak value, amplitude probability distribution (APD), and average power. The effect on received images was evaluated using mean opinion score (MOS) and bit error rate (BER). The relation between MOS and the ratio of desired and undesired signal levels (DU ratio) was investigated for actual digital TV and analogue TV signals. Results suggest that evaluation using the APD or the average power is appropriate because these methods are less affected by the type of disturbance. The relation between the MOS and the BER indicates that image quality can be roughly estimated from the BER.

This paper describes experimental and analytical results of electromagnetics pulses caused by electrostatic discharge (ESD). Energy spectra of ESD pulses measured by plural antennas are analyzed for three frequency domains (1-30MHz, 30-200MHz, 200-750MHz). Analytical results show that ESD energy does not always increase in proportion to discharge voltages and that ESD pulses produced by low voltage ESD may cause strong electromagnetic interference., IEEE 1992 International Symposium on Electromagnetic Compatibility, August 17-21, 1992, Anaheim, California

The calculation of the site free space voltage standing wave ratio (S VSWR ) is important in designing the measurement facilities used above 1 GHz. In this study, the relations between the area of the absorbers on the ground plane and the S VSWR were analysed using the FDTD method. The space, including the transmitting antenna, the receiving antenna, and the absorbers, were modelled using cells. The absorber constructed with foamed ferrite, ferrite tile, and wood was also modelled using cells. The calculation values almost agree with the measurement values, and the deviation between the calculation values using the FDTD method and the measurement values was smaller than the deviation between the calculation values using the ray trace method and the measurement values. The results suggests that the length similar to the distance between antennas is needed to acquire results similar to where absorbers are arranged over the entire ground plane (FAR), and that a width of 1.2 m also was needed to acquire the results similar to FAR.

A Mach-Zehnder interferometer whose half-wave voltage is about 4 V and a YAG laser pumped by a laser diode whose output power is 25 mW are used to improve the sensitivity of a LiNbO/sub 3/ electromagnetic field sensor. The resulting frequency response is almost flat from 100 Hz to 300 MHz and the minimum detectable electric field strength is 1 mV/m at 50 MHz and 0.14 mV/m at 750 MHz. The frequency response of the sensor is analyzed using the moment method, and the calculated results agree with the measured results. The improved sensor can measure an electromagnetic impulse whose peak value is larger than 10 V/m and width is wider than 5 ns., 1991 IEEE International Symposium on Electromagnetic Compatibility, 12 July-16 August, 1991, Cherry Hill, NJ, USA

Capacitive voltage probe (CVP) can measure the common mode disturbance voltages without contact to cables. However, it is necessary to obtain the correction factor for each cable within correction. Although the measurement method using two CVPs has been developed to measure the voltage without the correction, it needs two CVPs and a signal generator. This paper proposes the measurement method without correction using the loading capacitance changeable CVP (LCC-CVP). To evaluate the performance, a cable was replaced with a copper rod, and the deviation from the actual common mode voltage was measured. The results indicated that the deviation was within 3dB from 0.15 MHz to 30 MHz, the measurement value slightly changes depend on the loading capacitance value, and the deviation increases when the frequency is greater than 10 MHz. The disturbances from telecommunications equipment were measured to confirm the validity of the LCC-CVP. The results indicated that the measurement results were almost the same as the results using impedance stabilization network (ISN) when the sufficient large capacitance was used as the loading capacitance.

Pulse width modulation (PWM) is used to drive fan units in order to control them precisely. It creates a need to maintain the technology suppressing radiated emissions. Many studies are carried out to suppress emissions from PCB. However, mechanism of radiated emissions from an interface cable is not yet studied enough. In this paper, the radiation mechanism is studied using the fan unit model constructed with the fans and the drive circuit. The places of radiation source were investigated from the radiated electric field. The results show that the sources were placed at the interface cable connecting the drive circuit with the fan. The model was presented by the wire grid and the radiated electric field was calculated when the common mode current on the interface cable was the same as measured one. The results show that the calculation results almost agree with the measured one. The results also suggest that the radiation source was the drive pulse on the interface cable and the electric field was radiated from the interface cables and the AC-mains cables. The effect of the improving ground between the drive circuit and the fans was investigated from both the experiment and the analysis. The results indicated that the improvement of the ground was effective to reduce the radiation level.

The method of source modelling have been studied to estimate radiated emission at a distance of 10 m from the measured data at a distance of 3 m because the measurement facilities used the measurement at a distance of 10 m is expensive. However, the deviation between the measured and estimated values was more than 15 dB under a certain condition. In this paper, we study the method of improving estimation accuracy. The investigation indicated that the probability obtaining the optimum solution was majority. Therefore, to improve the estimation accuracy, we exclude the data that does not contain the range of standard deviation. The simulation using the calculated electric field was carried out. The imitated equipment was used as emission source, and the bilog-antenna was used as receiving antenna. The results indicated that the maximum deviation was reduced from 18 dB to 5dB. The radiated emission from a PC was estimated to verify the proposed estimation method. The result indicated the deviation was reduced from 4 dB to 3 dB.

Recent progress in home networks is increasing the interest in high-speed power line communication (PLC). This has the advantage of not needing the installation of new communication cable. However, the electromagnetic field radiating from the cable could disturb other radio communication systems. Thus, the field radiated from the cable should be evaluated In this paper, a pair of conductors of an indoor AC mains cable and its ground plane were represented by four-port networks and the common-mode current was calculated. In the calculation, the capacitance between conductors and between one conductor and the ground plane were obtained from numerical calculations to consider the effect of the cable insulator. The radiated magnetic field was calculated from the common-mode current distribution along the cable. The magnetic field radiated from a 4-m-long indoor AC mains cable was measured in an anechoic chamber to evaluate the validity of the calculation model. The results indicate that the deviation between the calculated and measured values was within 4 dB, and the radiated magnetic field strength was almost in proportion to the longitudinal conversion loss of an AC mains line. The calculation method was applied to an AC mains line with branches and the results almost agreed with the measured ones.

The recent progress of radio wave communication and high-speed electrical equipment has brought the need for radiation sources operating at more than 1 GHz to evaluate EMC test facilities and shielding characteristics. This paper proposes a radiation source using a disc-cone antenna with an O/E converter. A wire grid model construction based on a triangle was studied to maintain the wire density constantly, and a laser diode with an electroabsorption (EA) device was used as the E/O converter. The radiation source was constructed, and the characteristics were measured in an anechoic chamber from 0.3 to 10 GHz. The investigation indicated that the calculation accuracy was improved to employ the wire grid model based on a triangle, and the deviation between the calculated value and the measured value is within /spl plusmn/3 dB from 1 to 10 GHz. This also indicated that the deviation of the gain is within /spl plusmn/5 dB from 1 to 10 GHz and the maximum radiated field is more than 0.1 V/m at a distance of 1 m. Using the radiation source, the shielding effect of the PC case was investigated. The results indicated that the shielding effect decreased in proportion with the increase in frequency, and a careful design is important for maintaining the shielding effect in this frequency range.

The disturbance wave from a personal computer (PC) employing spread spectrum clocking was converted to the frequency range using a wireless LAN system. The wave was impressed on to the wireless LAN signal to investigate its influence on the radio telecommunication system using a broadband signal. The results indicate that the influence from a PC employing spread spectrum clocking was more serious than that from a PC not employing spread spectrum clocking. A frequency modulation signal and white noise were also impressed on to the wireless LAN signal. The result indicated that the frequency modulation signal, whose modulation frequency is from 1 kHz to 10 kHz and modulation frequency deviation is the same as that of the disturbances from a PC employing spread spectrum clocking, can be used as the artificial source to investigate the interference.

Influence to electromagnetic environment has been studied for power line communication (PLC). Longitudinal conversion loss (LCL) and input impedance are important parameters to evaluate the influence. Indoor AC mains line is modeled considering with typical conditions of Japanese house. The modeled line and electric equipment are presented with 4-port F-matrixes. The parameters of 4-port F-matrix are determined from calculation and measurement. Using this model, the input impedance and the LCL are calculated. The analysis model is examined by a simple network, and the results show that the calculation values almost agree with the measured values. The input impedance and the LCL are investigated for actual AC mains line, and the measured results almost agree with the calculated value., 2003 IEEE Symposium on Electromagnetic Compatibility, August 18-22, 2003, Boston, MA, USA

This paper describes the effect of amorphous magnetic-alloy film in achieving emission reduction. This film is expected to replace ferrite because of a high permeability that exceeds Snoek's limit and a low required thickness. In the investigation, an amorphous magnetic-alloy film was wound around a cable. Then, the cable's emission levels were measured in a semi-anechoic chamber at a distance of 3 m. We examined to what degree film length, film position, and film thickness have an effect on the emission reduction from cables protected with amorphous magnetic-alloy films. The experiment results indicated that a 1 m long region wound with the magnetic-alloy film was required in order to achieve identical emission reduction levels as those of typical ferrite cores. In addition, the results show that the reduction effect was enhanced when a ferrite core was used in combination with the film, and that there were few advantages in reducing emission when a metallic thin film was applied on one surface of the magnetic-alloy film.

The choke coil used in a telecommunications port for unshielded twisted pair (UTP) cable needs a high common mode impedance across a wide range of frequencies because UTP cable has no grounding port. A high permeability ferrite core was used to get a high common-mode impedance across a wide range of frequencies and a low level of insertion loss at high frequencies. As a result, the frequency range is about four times better than that for a conventional core and an insertion loss for telecommunications signals is about half that for the choke coil used with 10Base-T Using the coke coil for a 100Base-T LAN port, the measured improvement in immunity indicates that a wire length of more than 0.5 m is desirable to give sufficient performance.

We investigate the influence of a high-speed power line communication (PLC) signal induced into the very high-bit-rate digital subscriber line (VDSL) modem from the power line on the communication performance of VDSL. Differential-mode signal transmission loss between input signal at the modem's mains terminal and output signal at the modem's telecommunication terminal was estimated by using a 4-terminal-pair-network-model of the VDSL modem. We estimated modems supplied by two manufactures. The transmission losses were more than 45 and 70 dB and the throughputs were degraded when the signal power of the VDSL were attenuated by more than 38 and 45 dB, respectively

Electric field distribution below 80 cm should be specified to test the RF immunity of the floor-standing equipment. To determine this specification, a model in which the equipment is set on an infinite ground plane was used. Calculations using the moment method show that the height pattern of the field below 80 cm is independent of frequency. The height pattern measured in a room is close to the calculated pattern in this model. Experiments show that a suitable electric field can be almost generated by arranging RF absorbers on the floor of a semi-anechoic chamber., 1993 International Symposium on Electromagnetic Compatibility, 9-13 August, 1993, Dallas, TX, USA

Coupling and decoupling networks (CDNs) for two-wire, four-wire, and eight-wire telecommunication ports have been developed for use in radio-frequency conductive immunity testing. The requirements for the CDNs are based on the IEC recommendations, the telecommunication conditions, and the induced voltage at the telecommunication ports. The circuit parameters are chosen to meet these requirements. The measured characteristics of the CDNs show that they satisfy the requirements, and that they can be used for the immunity testing. >

The coupling coefficient between an electric field radiated from close to an overhead cable and the voltage appearing at the cable end is studied experimentally and theoretically. The calculated results closely agree with the experimental results. The voltage induced by a near radiation source is smaller than the voltage induced by a far radiation source for the same electric field strength at the cable.