• Journal of the Korean Ceramic Society
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• v.29 no.4
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• pp.293-297
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• 1992

A proper combination of complex permeability and permittivity is necessary to produce the zero-reflection microwave absorber with an impedance matching. Increasing of dielectric permittivity and development of an impedance matching was investigated in ferrite-rubber composite specimens by addition of conducting materials. Graphite powder of high dielectric constant was added to the composite specimens to increase the permittivity. The precise estimation of graphite content to produce the matched-wave-impedance absorber at a given frequency can be made by using the numerically derived solution map of impedance matching. It was suggested that permittivity adjustment is an effective technique to obtained the microwave absorber with both good absorbing properties and small thickness as well.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.3
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• pp.282-289
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• 2009

This paper presents an estimation technique of the equivalent circuit parameters for an underwater acoustic piezoelectric transducer from the measured impedance. Estimated equivalent circuit can be used for the design of the impedance matching network of the sonar transmitter. A fitness function is proposed to minimize the error between the calculated impedance of the equivalent circuit and the measured impedance of the transducer. The equivalent circuit parameters are estimated by using the fitness function and the PSO(Particle Swarm Optimization) algorithm. The effectiveness of the proposed method is verified by the applications to a sandwich-type transducer and a dummy load. In addition, the impedance matching network is also designed by using the estimated equivalent circuit model.

• ETRI Journal
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• v.28 no.3
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• pp.393-396
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• 2006

This letter proposes a new impedance matching scheme of a traveling wave electro-absorption modulator (TWEAM) module for a 60 GHz band radio-over-fiber (ROF) link. A microstrip band pass filter (BPF) was used to achieve impedance matching at the 60 GHz band, and termination resistance was carefully designed to obtain an input impedance close to $50\;{\Omega}$. Also, a bias circuit for the device was designed in the module. The measured return loss and frequency response show that the modulator module observes the characteristics of a filter without the need of a further tuning process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.519-527
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• 2010

In this paper, we proposed a 13.56 MHz wireless power transfer system using loop antennas with tunable impedance matching circuits. In general, a wireless power transfer system shows an impedance mismatching due to a reflected impedance, because a coupling coefficient is varied with respect to separation distance between two resonating antennas. The proposed system can compensate the effect of this impedance mismatch owing to tunable impedance matching circuits using varactor diodes. Therefore, transmission efficiency is enhanced, moreover, the center frequency of the system is not changed, regardless of separation distance between two antennas. In order to demonstrate the performance of the proposed system, a wireless power transfer system with tunable impedance matching circuits is designed and implemented, which has a pair of loop antennas with a dimension of $30\;cm{\times}30\;cm$ cm. The input return loss, coupling coefficient, efficiency, and input impedance variation with respect to a distance between loop antennas were measured. From measured results, the proposed system shows enhanced performances than the case of the general fixed $50\;{\Omega}$ impedance matching circuits. Therefore, we verified that the proposed wireless power transfer system using the proposed impedance matching scheme will be able to ensure robust operation even when the separation distance of antennas is varied.

• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.453-458
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• 2009

This paper presents two methods of designing a Broadband Impedance Matching (BIM) circuit for maximizing a power line communication (PLC) equipment (or Modem) signal injection into its load at any power line connection port. This optimal (BIM) circuit design is achieved in two phases: Butterworth gain function and Tchebycheff gain function. According to the comparison of simulation and practical results, the performances of two gain functions on BIM are discussed.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.800-804
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• 1995

The complex permeability dispersions and the microwave absorbing phenomena are investigated in ferrite microwave absorber. The complex permeability of NiZn ferrite, NiZnCo ferrite, and Y-type hexagonal ferrite were measured in 200MHz-14GHz range. Two types of resonances, the domain wall and the spin rotational resonance, were observed. With a ferrite particle with a diameter of about $1\;\mu\textrm{m}$, only spin rotational resonance were observed. The theoretical matching frequency is determined by plotting the measured complex permeability locus on the impedance matching solution map. One or two impedance matching phenomena are observed in the ferrite absorbers according to their complex permeability loci on the impedance matching solution map. The first matching frequency, found in the ferrite-rubber composites, which was higher than that of spin rotational resonance, increased with spin rotational resonance frequency.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.579-580
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• 2008

DRAM설계시 DDR2에서부터 고속 동작으로 인해 반송파에 의한 신호외곡으로 impedance matching의 필요성이 대두되었다. 이로 인해 제안된 방법은 외부 Termination 저항(RZQ)을 기준으로 impedance matching을 위한 Rtt 저항의 생성이다.[1] 제안된 ZQ Calibration 회로는 기존의conventional ZQ Calibration 회로에 After ZQ calibration block을 추가하여 한 번 더 교정함으로써 마지막 PMOS Array와 NMOS Array 저항 값이 Termination 저항 값에 가깝도록 설계하였다. 따라 전력효율은 그대로 유지하면서 ${\Delta}VM$의 오차범위를 기존의 ${\pm}5%$이내에서 skew 조건에 따라 ${\pm}1.33%$까지 향상시키는 것을 볼 수 있다. (JEDEC spec. ${\pm}5%$이내).

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.69-75
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• 2001

In this paper, a fast and easy impedance matching method, which could give the impedance matching component for the general 1 or 2-port network was introduced. First, the entire network structure was defined which consists of the network part to be matched and the impedance matching part composed of inductors and capacitors. Next, the transmission matrix and input and output impedances of the entire network from the terminal impedance conditions were calculated, then the exact solutions for the matching components were obtained. To verify the efficiency of this method, this method was applied to the CDMA If band withdrawal weighted SAW transversal filter, and investigated the effects of the impedance matching before and after, through the simulation and experiment. As the result, the performance of a fractional bandwidth of 1.2%, insertion loss of 29 dB, and VSWR of 80 have improved to a factional bandwidth of 1.8％, insertion loss of 9 dB, VSWR of 3 at 85.38 MHz center frequency. The result shows that this impedance matching method could be used in the SAW devices and other types of 1 or 2-port network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.286-291
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• 2013

In this paper, a compact rectenna system is designed using a circular sector antenna with harmonic-rejecting characteristics and a direct impedance matching method. The system is designed with bandpass filtering performed by the harmonic-rejection of the circular sector antenna and without impedance matching circuit for the diodes by the direct impedance matching technique. Therefore, while the rectifying circuit of the proposed system can be implemented without a bandpass filter and a impedance matching circuit, it is integrated on the back side of the antenna using precise fabrication techniques for coaxial feedings without degrading the system performances corresponding to the feeding points. From the experimental results, the optimized rectenna system has presented excellent performances of a conversion efficiency of more than 52 % and a conversion voltages of more than 1.5 V at 2.5 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.59-65
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• 2012

This paper presents a digital control solution which can extract the reactor parameters in atmosphere plasma power supply. The critical issue of the atmosphere plasma power supply is a impedance matching. For the impedance matching, the reactor parameters should be known, but the parameters depend on the reactors. Therefore, the reactor parameters have to measure for the impedance matching. The proposed method is performed by detection of phase difference between inverter voltage and current, and extraction of impedance through active, reactive power.