Search

Theoretical and experimental investigations were carried out on the characteristics of the shunt-type asymmetric artificial network (AAN). The findings are as follows: 1) The theoretical formulas for the differential- and common-mode impedances as well as the longitudinal conversion loss (LCL) were derived for the shunt-type AAN in terms of the AAN circuit parameters. 2) The common-mode disturbance voltage estimated from the measured voltage is not proportional to the actual common-mode current flowing in the network cable of the equipment under test (EUT). 3) For the common-mode EUT, the shunt-type AAN with a low LCL of less than about 42 dB yields incorrect measurement results with an error greater than 0.5 dB. 4). A more crucial problem is that, for the differential-mode EUT, the measured disturbance voltage decreases as the EUT common-mode impedance decreases. [ABSTRACT FROM PUBLISHER]

Conducted asymmetric disturbances are measured at telecommunication ports of equipment under test using an asymmetric artificial network (AAN). Therefore, theoretical investigations are carried out to characterize an AAN with a mode-impedance matrix, introducing the common-mode and differential-mode impedances. By referring to this matrix, a theoretical design method is developed for the AAN with an asymmetrical transformer to satisfy the requirements for the mode impedances and the longitudinal conversion loss. By using this design method, two different prototype AANs are assembled: one meets the CISPR 22 specifications, and the other is used in power line telecommunication modem tests. A detailed experimental examination of the assembled AANs validates the proposed theoretical design method. [ABSTRACT FROM PUBLISHER]

New pyridinium type thermotropic ionic liquid crystal materials having a 1,3-dithiane ring in the central core N-substituted 4-(5-alkyl-1,3-dithian-2-yl)pyridinium bromides and the corresponding 1,3-dioxanes were synthesized and their mesomorphic behaviours compared. The principal feature of these compounds is to exhibit a smectic A phase over a very wide temperature range including room temperature. [ABSTRACT FROM AUTHOR]

In the radiation immunity test for telecommunication equipment, an electromagnetic applicator such as chamber, a transmission electron microscopy (TEM) cell and a general transmission electron microscopy (GTEM) cell are used. Characteristics that include a semianechoic uniformity of the electromagnetic field without a device under test have been evaluated. However, characteristics that include an electromagnetic field in the presence of the device under test have not been reported. In this paper, it is recognized that these electromagentic application are designed in such a way that they can generate an electromagnetic field distribution generated by the plane wave incident on a conducting sphere, the electric field is evaluated and compared in the case in which the device under test is placed within the application. Further, evaluation results are include for the size of the device under test for which the immunity test is possible in each applicator. The evaluation method first derives the theoretical value of the scattered electric field when a plane wave is incident on the conducting sphere in free space. Next , these theoretical values are compared with the measured electric field values around the conducting sphere in each electromagnetic applicator. It was found that the difference between the measured and the theoretical results is the smallest and the frequency dependence is the lowest in a semianechoic chamber. In the case of a TEM cell and a GTEM cell, it was found that the difference between the measured and the theoritical values is less than +6 dB if the magnitude of the device under test is less than one-third the spacing between the inner and outer conductors. [ABSTRACT FROM AUTHOR]