Wilkinson Power Dividers/Combiners The in-phase power combiners and dividers are important components of the RF and microwave transmitters when it is necessary to deliver a high level of the output power to antenna, especially in phased-array systems. In this case, it is also required to provide a high degree of isolation between output ports over some frequency range for identical in-phase sig...

Abstract—This paper presents a novel tri-band unequal Wilkinson power divider. The proposed structure is derived from the conventional unequal Wilkinson power divider by replacing the quarter-wavelength branch lines and quarter-wavelength transformers with the extended T-shaped short stubs and three-section transformers respectively. The first and third operating frequencies of the proposed Wil...

The aging of oil-paper insulation in power transformers may cause serious power failures. Thus, effective monitoring of the condition of the transformer insulation is the key to prevent major accidents. The purpose of this study was to explore the feasibility of confocal laser Raman spectroscopy (CLRS) for assessing the aging condition of oil-paper insulation. Oil-paper insulation samples were ...

Millimeter-wave wireless communication systems have considerably gained in importance in recent years. Important applications as 60-GHz WLANs and WPANs, 80-GHz automotive radar, and 94 GHz imaging have emerged, requiring significant effort on the design of transceiver's silicon-based integrated circuits. In this context, integrated transformers are of a particular interest. They may perform, am...

This paper presents a novel quad-band power divider with equal power division ratio. The proposed power divider is realized using two cascaded sections of dual-band transformers based on coupled microstrip lines. Limitations of using dual-band quarterwavelength transformers based on coupled lines are studied through parametric analysis to obtain useful design guidelines related to available fab...

This paper presents an efficient wavelet and neural network (WNN) based algorithm for distinguishing magnetizing inrush currents from internal fault currents in three phase power transformers. The wavelet transform is applied first to decompose the current signals of the power transformer into a series of detailed wavelet components. The values of the detailed coefficients obtained can accurate...

Most power transformer failures are associated with the presence of corrosive sulfur compounds in mineral insulating oil, which dibenzyl disulfide (DBDS) is best known and most widespread compound. The oil failed transformers usually contained DBDS, a compound pronounced affinity for formation copper (I) sulfide (Cu2S). Copper that does not dissolve conducts electricity, can be deposited on pap...

Microwave hybrids The branch-line couplers or hybrids were firstly described more than six decades ago; however, the problem of their exact synthesis remained a puzzle for a number of years [53]. Initially, the branch-line hybrid was analyzed as a four-arm symmetrical network based on a superposition of the results obtained in the even and odd modes [54]. By writing the even and odd mode matric...