• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.4
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• pp.382-389
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• 1997

We present the results on the applicability of the polycrystalline AIN thin films for a surface acoustic wave filter operating at 800 MHz frequency. The films show the FWHM of 3 .deg. from th X-ray rocking curve, which indicates that the c-axis of the films is pre- ferentially oriented along the growth direction. The fabricated band pass filters exhibit the center frequency of 865 MHz with 3dB band-width of 45 MHz. From the measured frequency response, the electro-mechanical coupling constant of 0.8% and the SAW velocity of 5,709 m/s are obtained. Thus, we conclude that the sputtered AIN films are feasible for the fabrication of uper UHF band SAW filters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.636-636
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• 1997

This paper presents the design and fabrication of a shaped-beam array antenna which will be used for a PCS basestation using structure that is coupled to a microstrip line by an aperture on the intervening ground plane. The shaped-beam pattern is obtained by an antenna synthesis method. An array antenna considering the mutual coupling between array elements(patches) and a feeding network are designed by CAD tools. The feeding network is designed by using the Wilkinson power divider to obtain the optimized shaped-beam. The designed results are compared with the measured data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.245-251
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• 2011

In this paper, dual-band bandpass filter by using Pseudo-Interdigital Stepped-Impedance Resonator(PI-SIR) and Open-Loop Ring Resonator(OLRR) is proposed. The first passband and second passband are formed by PI-SIR and the second passband is reinforced by an OLRR. In a PI-SIR the first band and second band are easily and exactly adjusted by characteristic impedance ratio and electrical length ratio. The proposed design method may be confirmed to be useful from fabricated and measured results for dual-band bandpass filter operated at 2.45 GHz and 5.8 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.252-257
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• 2011

A compact microstrip dual-band bandpass filter with controllable bandwidth for each passband is proposed. Each passband is independently designed using two different dual-mode resonators. The proposed dual-band bandpass filter has three transmission zeros. Two transmission zeros are generated by each dual-mode resonator. An additional transmission zero is generated by input/output port coupling. The dual-band bandpass filter application is designed for 2.4/5.7 GHz WLAN. Experimental results are presented to validate theory.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.173-181
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• 2011

In this paper, we propose a half mode substrate integrated waveguide(HMSIW) balanced bandpass filter to yield improved isolation between output ports. In order to achieve good isolation, resistive coupling slot is employed in HMSIW filter. The measurement results show that the insertion losses($S_{21}$, $S_{31}$) are $5.4{\pm}0.2$ dB and input return loss($S_{11}$) is more than 10 dB from 5.8 GHz to 6.4 GHz. Moreover isolation between output ports is larger than 18 dB and phase difference of output ports is $180{\pm}10^{\circ}$.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.329-331
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• 2014

A simple realization of an alignment-free wireless power transmission (WPT) system is presented in this letter. The WPT system consists of a transmitter with three reconfigurable modes corresponding to various controllable magnetic field directions in the azimuthal plane and an algorithm for the optimum mode selection carried by sensing the reflected voltage of the system. Twelve light emitting diodes (LEDs) are used to confirm the on- and off-state of LEDs powered wirelessly by the transmitter at every $15^{\circ}$ of the azimuthal plane. A criterion voltage from the reflected power of the system is found by using the correlation between the reflected voltage and the on- and off-state of the LEDs. Simply by continuous; monitoring of the voltage from the system, the system maintains power to the LEDs. The system is realized by MATLAB/Simulink and a National Instrument data acquisition device (DAQ) board. Measurements using the system show on-state LEDs in the azimuthal plane except at the angles of $60^{\circ}$, $75^{\circ}$, $180^{\circ}$, and $300^{\circ}$.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.609-614
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• 2015

Implanted telemetry systems provide the ability to monitor different species of animals while they move within their cages. Species monitored include mice, rats, rabbits, dogs, pigs, primates, sheep, horses, cattle, and others. A miniature transmitter implanted in each animal measures one or more parameters. Parameters measured include arterial pressure, intra-pleural pressure, left ventricular pressure, intra-ocular pressure, bladder pressure, ECG, EMG, EEG, EOG, temperature, activity, and other parameters and transmits the data via radio frequency signals to a nearby receiver. Every conventional dedicated transmitter contains one or more sensors, cpu and battery. Due to the expected life of the battery, the measuring time is limited. To overcome these problems, electromagnetic inductive coupling based wireless power transmission technology using multiple transmit coils were proposed, with each coil having a different active area driven by the coil driver. In this research, a parallel resonance based coil driver and serial resonance based coil driver are proposed. From the experiments we see that the parallel coil driver shows better performance under a low impedance and multiple coils configuration. However, the serial coil driver is more efficient for high impedance transmit coils.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.27-36
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• 2001

In this paper, micromachined millimeter-wave cavity resonators ar presented. One-port and two-port cavity resonators at Ka-band are designed using 3D design software, HP $HFSS^{TM}$ ver. 5.5 Cavity resonators are fabricated on Si substrate, which is etched down for the cavity, bonded with a Quartz wafer in which metal patterns for the feeding line coupling slot are formed. One-port resonator shows the resonant frequency of 39.34 GHz, the return loss of 14.5 dB, and the loaded $Q(Q_{L})$ of 150. Two-port cavity resonator shows the resonant frequency of 39 GHz, the insertion and return losses of 4.6dB and 19,9dB, the loaded($Q_{L}$) and unloaded $Q(Q_{U})$) of 44.3 and 107, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.110-118
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• 2004

In this paper, a method is presented for the design of an orthomode transducer(OMT) operating at 21/31GHz frequency bands. A square waveguide is used in the common port while the WR-34 standard rectangular waveguide is used in the straight port. The straight port is connected to the common port via a multi-stage quarter-wave impedance transformer. The side port is coupled to the common port through a slot formed along the center line of the common square waveguide. An impedance transformer is employed to match the impedance of the coupling slot with that of the WR-51 waveguide at the output of the side port. Dimensions of the OMT are iteratively optimized employing the theory of waveguide. The validity of the proposed method is verified by fabricating and testing the designed orthomode transducer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.36-43
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• 2004

In this paper, we proposed a novel compact microstrip lowpass filter with an ultra-wide stopband and prominent cutoff sharpness using slot on the ground plane and microstrip shunt open stub. The microstrip shunt open stub and slot exhibit the different stopband response. The combined characteristics of these structures gives the ultra-wide stopband characteristics and the coupling effect between slots on the ground plane makes the prominent cutoff sharpness. The fabricated microstrip lowpass filter with the size of 20.1 mm ${\times}$ 18.7 mm has -3 ㏈ cutoff frequency at 1.187 ㎓ and -20 ㏈ stopband from 1.33 ㎓ to over 20 ㎓ and the insertion loss in the passband is less than -0.4 ㏈ form DC to 1 ㎓.