• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.149-151
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• 2015

Coupling with a ring of capacitors introduces in-phase coupling current in multi-stage LC oscillators, increasing coupling strength and phase spacing accuracy. Capacitive coupling is effective at high-frequency applications because it increases coupling strength with the operating frequency. However, capacitive loading from the ring lowers operating frequency and reduces the tuning range. Mathematical expressions of phase noise and phase spacing accuracy with capacitive coupling are examined here, and transistor-level simulations confirm the effectiveness of the capacitive coupling.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1121-1127
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• 2014

In this paper, a planar frequency reconfigurable antenna is proposed with variable capacitors. The proposed one is designed with a planar monopole, and varies resonant frequencies by variable capacitive loading of a varactor diode. The equivalent circuit and electromagnetic(EM) simulation are utilized for the analysis at the variable characteristic design of the antenna, and the same radiation performance. The implemented frequency variable monopole antenna has been verified by comparing prototypes with designed capacitors and ones with biased varactor diodes. The proposed antenna has presented the resonant frequency variations from 2.25 GHz to 2.42 GHz.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.426-429
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• 1988

A simple design method of a single balanced MMIC mixer is described. It uses small signal S11 and capacitive load for the input matching circuit and the output loading circuit, respectively. It is found that the conversion gain of the FET mixer is independent of FET gate width. The fabricated mixer has 2.5 dB conversion gain at 9 GHz with 50 ohm IF load and 2 dBm local oscillator power.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.7-12
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• 2010

The bandwidth of a Jerusalem AMC was investigated based on the equivalent circuit model. Using the circuit model and the derivative of the admittance(Y'), the relation between the bandwidth and various circuit parameters was analyzed. It was shown that the substrate thickness and permeability enhance the bandwidth whereas the loadings on FSS grid degrade the bandwidth. Among the two loadings, the capacitive loading had better bandwidth characteristics than the inductive loading. AMC with single polarization was suggested to relax the bandwidth degradation by the inductive loading.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.401-404
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• 2002

This paper proposes a new symmetrical bandpass filter based on capacitive loading with a coplanar waveguide (CPW) structure. The filter was numerically designed at the operating frequency around 2 ㎓ by using IE3D software package. The characteristics of the proposed filter were then measured which the results were in good agreement with simulation. The passband insertion loss was considerably low (~3 ㏈) and the return loss was high (greater than 10 ㏈). The size of the proposed filter was also decreased approximately 50% when comparing with the fitters using conventional transmission lines.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1035-1038
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• 1999

To improve the damping of all poorly damped oscillation modes, a control strategy of Static Synchronous Series Compensator (SSSC) based on energy method is presented in this Paper As a synchronous voltage-sourced inverter, SSSC is used to provide controllable series compensation. SSSC can provide controllable compensating voltage over an identical capacitive and inductive range. The damping effect of control strategy based on energy function is robustness with respect to loading condition, fault location and network configuration. Furthermore, the control inputs are based on local signals. In two area system, the effect of damping inter-area mode oscillation is demonstrated by the robust control strategy of SSSC.

• ETRI Journal
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• v.30 no.4
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• pp.615-617
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• 2008

A novel and compact elliptic-function bandpass filter is proposed in this letter. The techniques of slot etching and the addition of open stubs are applied to enhance the self-inductance and self-capacitance of hexagonal open-loop resonators. Thus, size reduction and improved transmission performance are obtained. Compared to the performance of the conventional design, the central frequency and insertion loss are reduced by 28% and 3.1 dB, respectively. Measurements show that the proposed filter has a fraction bandwidth of 23% at the central frequency of 1.84 GHz, and its insertion loss in the passband is less than -1.5 dB. The bandpass filter occupies only 12 mm${\times}$21.2 mm (approximately $0.24{\lambda}_g{\times}0.14{\lambda}_g$).

• ETRI Journal
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• v.31 no.3
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• pp.254-262
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• 2009

This paper presents a novel simple filter design method based on a parallel short-ended coupled-line structure with capacitive loading for size reduction and ultra-broad rejection of spurious passbands. In addition, the introduction of a cross-coupling capacitor into the miniaturized coupled-line can create a transmission zero at the second harmonic frequency for better frequency selectivity and attenuation level. The aperture compensation technique is also applied to achieve a strong coupling in the coupled-line section. The influence of using the connecting transmission line to cascade two identical one-stage filters is studied for the first time. Specifically, such a two-stage bandpass filter operating at 2.3 GHz with a fractional bandwidth of 10% was designed and realized with low-temperature co-fired ceramic technology for application in base stations that need high power handling capability. It achieved attenuation in excess of -40 dB up to $4f_0$ and low insertion loss of -1.2 dB with the size of 10 mm ${\times}$ 7 mm ${\times}$ 2.2 mm. The measured and simulated results showed good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.694-700
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• 2009

In this paper, we propose a RFID tag antenna with low performance degradation due to nearby dielectric materials. The proposed antenna is designed to be appropriate for ink printing fabrication. The antenna is designed to operate in UHF band of $860{\sim}960$ MHz. The antenna uses a T-matching network in the middle of the main body and two parasitic patches in vicinity for complex conjugate matching with a commercial tag chip. In addition, the two parasitic patches induce currents at different dielectric constants of nearby dielectric materials. This can minimize the performance degradation due to nearby dielectric materials. The measured results show the half power matching bandwidth from 844 MHT to 1,268 MHz. It exhibits the reading distance of about 3.5 m in free space when the tag antenna is used with the commercial reader antenna (transmitting power of 20 dBm and the reader antenna gain of 6 dBi). When the tag is attached on dielectric materials of wood and FR4, the resulting reading distances are 2.61 m and 2.51 m, respectively.