Hiroshi Echigo

Ku-band long distance site-diversity (SD) Characteristics using new measuring system

This paper deals with the short (10 km) and long distance (300-1400 km) site-diversity (SD) characteristics by using a newly developed measuring system. In the proposed measuring system, six earth stations transmit 14-GHz band QPSK signals, and one measuring earth station receives 12-GHz band signals and processes them to determine SD characteristics. As a result, easy operation and maintenance, low-cost measuring system construction and highly accurate data have been obtained. By comparing those measured results with the SD joint probability approximation equation in ITU-R Rec.P.618-7, a good agreement can be obtained. Furthermore, the effect of typhoons on SD characteristics were measured.

Frequency spectra of the arc current due to opening electric contracts in air

Frequency spectra of the electromagnetic noise due to arc current caused by Ag contacts upon opening in air at atmospheric pressure are described. To take into consideration the fast transients and high-frequency discharge phenomena at the contacts, a distributed constant model consisting of relay contacts and a coaxial distributed constant line is introduced. An experiment carried out under conditions of low circuit current (3.84 A) and low source voltage (48 V) is reported. The results indicate that the frequency spectra of the arc currents depends on the length and terminal conditions of the line connected to the contacts. >

Long distance site-diversity (SD) characteristics by using new measuring system

This paper deals with the short and long distance (10-1400 km) site-diversity (SD) characteristics by using a newly developed measuring system. In the proposed measuring method six Earth-stations transmit QPSK signals and one measuring Earth-station receives signals and processes them for site-diversity characteristics. As a result, easy operation and maintenance, low cost measuring system construction and high accuracy data can be obtained. By comparing these measured results with the site-diversity joint probability approximation equation in CCIR Rep. 564-4, relatively good agreement can be found.

A method for measuring transients caused by interrupting current using a transmission line terminated in its characteristics impedance

A measurement method of transients caused by interrupting a current is described. In consideration of the fast transients and high-frequency discharge phenomena due to interrupting the current, a transmission-line system was introduced. It consists of a coaxial switch, coaxial cables as transmission lines on the right and left sides of the switch, and termination resistors. When the current is interrupted by the switch, the waveform across the termination resistor is measured by an oscilloscope. The impedance-matching technique for the cables was employed to minimize the effects of reflected waves. That is, the resistors were designed to match the characteristic impedance of the cables. The characteristics of the system were measured by a network analyzer. The VSWR of the system was within 1.33 in the frequency range below 500 MHz. The time-domain measurement using a transmission-line system terminated in its characteristic impedance clears up the process of the complicated transients caused by interrupting current. >

Radio noise measurement near the vehicle traffics

This paper describes the radio noise measurement in the VHF band near a road with busy traffic. Newly developed APD measuring equipment was used for this measurement together with a spectrum analyzer. The obtained results show the time dependent variation of the statistical characteristics of the noise. The statistical characteristics of the variation would be important for the estimation of EM environments.

EM Fields Between Two Parallel Plates Supported by Conductive Multi-Poles - Pole-Plate System: Shield Effectiveness and Field Leakage

In conductive multi-plates such as printed circuit boards (PCB) or pin grid array (PGA) connectors of CPU ICs, EM fields should be analyzed because undesired coupling between Vias and Pins may occur. In addition, the shield effectiveness of the pin array in preventing the leakage of EM field should be estimated. In this paper, some examples are shown to prove that the analysis method for the scattering of a multi-wire system is effective. Some calculation results giving the electric near-field images are presented for thin-wire systems and multi-plate conductors. They clearly give the field pattern caused by scattering out of the pole conductors. These results will give intuitive estimations of the EMI and lead to better treatments in the design.

Frequency Spectra of Arc Voltage due to Electrical Contacts on Opening with Arc Discharge

Frequency spectra of the middle of an arc voltage waveform caused by electrical contacts on opening with the arc discharge are described. In this investigation, introduced was a model which consisted of a relay and a coaxial line. Based on the model, the frequency spectra of it were analyzed experimentally. As a result, it is concluded that they depend on the length and terminal condition of the line directly.

EM near fields formed by scattering of multi-wire conductors under illumination of TM plane wave

The near fields around transmission lines on PCB should be estimated clearly because they are the main EMI sources in the digital equipments. The method to analyze the fields should be easier one and not be time consuming one. The authors have been studying on the EM wave scattering out of conductive rods with infinite length. Basing on these analyses, the analyzing method targeting to the near fields could be available basing on the fact that the near fields are formed by the scattered waves out of conductive plates which are supposed to be composed of many thin wires. Using this thin wire approximation, the EM fields around the plate conductors are easily obtained. In this paper, some calculation results are given for the thin wire systems and the multi-plate conductors as the electric near-field images. They give vividly the standing wave pattern caused by the reflection and the re-radiation out of the conductors showing how interferences appear and propagate, adding their shading effects. These results give the estimations of the EMI intuitively and it leads to better treatments in the design.

Simulation of cutoff frequencies in TEM cells by boundary scaling functions

In this paper we show that the scaling function system can be used for the evaluation of cut-off frequencies in TEM cells. We use the penalty method to handle boundary conditions and calculate eigenvector solutions, enabling higher order mode field configurations to be visualized.

Demonstration of radio noise measurement

This paper shows radio noise measurement in VHF band. Newly developed APD measuring equipment were used for this measurement together with a spectrum analyzer. Some results are given.