Ji-Hoo Kim

A dipole-coil-based extremely loosely coupled inductive power transfer system (IPTS) for wireless sensors over a wide range is proposed. The overall superiority of dipole coils for a long-distance power delivery over loop coils with an identical configuration of a square core is verified by comparing the magnetizing inductance between primary and secondary coils. Series-parallel resonant circuits were used to achieve a higher load voltage than that of the series-series scheme. Contrary to conven

A universal wireless power transfer (U-WPT) system which can be used for not only roadway-powered electric vehicles (RPEVs) but also stationary charging of electric vehicles (EVs) is newly proposed in this paper. Contrary to previous WPT systems for RPEVs, the proposed U-WPT can also be used for pick-ups fabricated by the SAE J2954 standard for stationary charging. The proposed U-WPT adopts a new coreless power supply rail to increase its operating frequency from the conventional level of 20 kHz

In this article, a novel structure of a receiving (Rx) coil with only two coils, which enables omnidirectional wireless power transfer (WPT) for any type of transmitting (Tx) system, is proposed for the first time. The coil adopts each coils into plane cross-shaped ferrite core, with each leg of the ferrite core intersecting both coils. The intersecting direction of the ferrite core for one coil is identical to that of the other one when it is rotated 90 degrees. It is verified that voltage will

A novel synthesized magnetic field focusing (SMF) technology is proposed and nonradiative but focused magnetic field is experimentally demonstrated as a one-dimensional example. Contrary to common belief, a magnetic field can be focused arbitrarily by increasing the number of current-controlled transmitting coils in a manner similar to that of conventional beam-forming. Moreover, the proposed SMF is independent of frequency from dc to rf. Chronic problems associated with conventional wireless po

Abstract In this article, we have proposed a dual‐band antenna with U‐shaped open stub for wideband local area network (WLAN)/ultra wideband (UWB) applications. The designed dual‐band antenna consists of two semicircle radiating patches, a rectangular slot separating the two semicircles, one step for impedance matching, and coplanar waveguide (CPW) feeding. Two kinds of prototypes (CPW‐fed UWB antenna and the dual‐band antenna with U‐shaped open stub) are fabricated and measured. Parametric stud

An extremely loosely coupled inductive power transfer system (IPTS) for 7m-off-long-distance wireless power transfer using dipole coils is proposed. The superiority of dipole coils for a-long-distance power delivery over loop coils with same configuration of square core, in general, is verified by comparing magnetizing inductance between primary and secondary coils. Series-parallel resonant circuits are used to achieve higher load voltage than the series-series scheme. Contrary to conventional I

In this paper, a novel loop coil structure for synthesized magnetic field focusing (SMF) technology and two current distribution calculating algorithms in the structure are proposed. The proposed structure enables field focusing in two-dimensional (2-D) space for the first time. The loop coil structure with a rectangular formation is adopted for a 2-D SMF system to minimize the volume and weight of the transmitting (Tx) coil array considering that conventional SMF systems inevitably have a volum

A new source-side monitored capacitive power transfer system (CPTS) for contactless mobile charger using Class-E converter is proposed. Contrary to conventional contactless mobile charger, an exact battery voltage monitoring is achieved without additional cumbersome communication circuits. The proposed CPTS operates in two iterative modes; a main-charging-mode and a sub-battery-monitoring-mode. Not only the battery voltage sensing but also an agile battery charging current control is accomplishe

An optimal ampere-turns design for a long-distance dipole-coil-based inductive power transfer (IPT) system for maximum power efficiency is proposed in this article. Assuming that specific requirements, which are the target load power, the physical size of the transmitting (Tx) and receiving (Rx) coils, and the distance between the Tx and Rx coils, are given, quantitative analyses on the optimal ampere-turns of loosely coupled Tx and Rx coils to satisfy the constraints with maximum power efficien

A prototype of a high-resolution synthesized magnetic field focusing (SMF) system for a possible application to radio frequency (RF) barcodes is proposed in this paper. It was recently found that coordinated control of array coil currents makes it possible to focus magnetic field, which is requisite for medical imaging, wireless power, and RF identification. Different from conventional phased array RF antennas, SMF is independent of frequency, which is quite promising for various applications. I

A new curved-type reflector for solar power generation is proposed. By adopting the curved-type reflector between consecutive solar panel arrays, all incoming sunlight can be utilized and thus, the generated power is significantly increased. Furthermore, the proposed curved-type reflector can be generally used in four seasons regardless of the altitude or angle of the installation environment. The optimum design rule for the curved-reflector, comparing to a plane-type reflector, is completely de

In this article, a novel method to calculate the current distribution, which enables the active sidelobe suppression of the magnetic flux density in an synthesized magnetic field focusing (SMF) system, is proposed for the first time. The proposed method calculates the current distribution, which enables further sidelobe suppression and keeping the resolution at the same time, by changing the target magnetic flux density distribution with only one varying parameter. The proposed calculation metho

We report a 5 GHz linear InGaP/GaAs HBT monolithic microwave integrated circuit (MMIC) power amplifier for wireless LAN applications. The three-stage power amplifier operates with 103 mA - low quiescent current of Class AB mode using active bias circuit under a single supply of +3.3V A total current of 196(194) mA is consumed with an output power of 18 dBm and PAE (power-added efficiency) of 9.7% at 5.25(5.15) GHz. The power amplifier exhibits a power gain of 19.6 (17.8/18.5) dB, 1-dB compressio

In this paper, we have proposed a compact UWB antenna with PI-shaped (pi-shaped) matching stub for UWB applications. The antenna has a modified trapezoidal radiating patch, a PI-shaped matching stub, CPW feeding, and two steps for impedance matching. To evaluate the dispersion performance of the designed UWB antenna, the path loss (|S21|) and the group delay are simulated and measured. Details of the proposed antenna design and the simulated and measured results are presented and discussed.

Crossed dipole coils for the wide-range 3-D omnidirectional inductive power transfer (IPT) are proposed. Free positioning of a plane receiving (Rx) coil is obtained for an arbitrary direction within 1m from a plane transmission (Tx) coil. Both the Tx and Rx coils consist of crossed dipole coils with an orthogonal phase difference; hence, a rotating magnetic field is generated from the Tx, which enables the Rx to receive power vertically or horizontally. Chronic installation problems associated w