• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.59-64
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• 2008

In this paper an adjustable linear gain equalizer which is operated from 6GHz to 18GHz in order to apply wideband RF circuit System is proposed and fabricated on $Al_2O_3$ substrate using thin film process. An adjustable linear gain equalizer is proposed to T type circuit and designed to aim on variable slope $-7dB{\sim}-13dB$ using the PIN Diode

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.63-69
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• 2007

The directivity of crossed waveguide directional coupler is generally decreased according as coupling coefficient of it increase. In this paper, the geomertical parameters of crossed slot pair for directivity improvement is modified and the formulas for design of it are proposed. The crossed waveguide directional coupler designed upon the formulas is fabricated with the WR42 waveguide in K-band. The measured results show that the coupling coefficient is 21.5 dB and directivity is minimum 23.9 dB over the operating frequency from 18GHz to 26.5GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.104-108
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• 2009

In this paper, we investigate the performance of ARQ-aided downlink Time Switched Transmit Diversity (TSTD) in the WCDMA LCR-TDD system. Proposed TSTD system applies the ARQ scheme in which the receiver sends the response signal (ACK or NACK signal) to the transmitter and predicts the channel condition based on response signal after receiver checks the error, then it re-sends data. Simulation results demonstrate that the proposed TSTD scheme yields about 5.5dB performance gain, compared with the conventional TSTD in term of the frame error rate(FER) for a mobile speed of 3km/h and an FER value of 1%. In addition, 7% of throughput gain is shown when Eb/N0=7dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.162-167
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• 2009

In this paper, we present a compact Ultra-Wideband band-pass filter using a high-pass filter and low-pass filter. The structure of our proposed band-pass filter is very simple and the DGS(Defected Ground Structure) structure is used to get the low-pass filter characteristic. Our proposed band-pass filter can be much smaller than a cascaded filter. As a result of measurement the insertion loss is less than 0.5dB throughout the pass-band of $2.1GHz{\sim}10.56GHz$, the return loss is more than 20dB and the group delay maximum variation is 0.23ns from 0.12ns to 0.35ns.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.63-68
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• 2004

The capacity of MIMO systems is numerically analyzed when channel estimation error exists. The analysis shows that the capacity is influenced by Mean Square Error (MSE) as well as average Signal to Noise Ratio (SNR). Furthermore, in this paper we present the standard selecting a channel estimator suitable to a system owing to get a tolerable channel estimation error in a given average SNR and channel capacity loss. The simulation results show that the tolerable MSEs for 1 bps/Hz capacity loss are about 10$^{-2}$ and 10$^{-4}$ at n dB and 40 dB average SNR, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.2
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• pp.1-5
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• 2001

We propose an optical performance monitoring method for WDM optical transmission systems. By assigning a pair of AWG ports to each optical signal channel. the optical power, optical signal-to-noise ratio (OSNIO, and wavelength of all the signal channels are observed simultaneously. The output power ratio of the AWG port pair depended on the wavelength variation of the channel with sensitivity of 1dB/0.026nm. The OSNH results were deviated no more than 0.7dB from the results measured by optical signal analyzer (OSA).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.126-133
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• 2009

In this paper, The planar waveguide slotted antenna is presented for a satellite communication of vehicles. In stead of the microstrip patch array antenna having a dielectric loss and a feeding loss, the proposed antenna has the 3-layered waveguide feeding network structure for assembling easily. Also this antenna can receive mechanically both RHCP and LHCP transmitted from a satellite using a polarizer made from a thin single layer film. The Gain of the proposed 4X8 array antenna is 27.5dB and the gain of 8X16 array antenna is 32dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.89-94
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• 2011

In this paper, we developed the W-band MMIC low noise amplifier for the millimeter-wave seeker using the tuner system. The MHEMT devices for MMIC LNA exhibited DC characteristics with a drain current density of 692mA/mm, an extrinsic transconductance of 726mS/mm. The current gain cutoff frequency(fT) and maximum oscillation frequency($f_{max}$) were 195GHz and 305GHz, respectively. The fabricated W-band low noise amplifier represented S21 gain of 7.42dB at 94 GHz and noise figure of 2.8dB at 94.2 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.58-63
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• 2000

For the microwave high density devices and modules of the 3D configuration, we proposed radial stub for the ground connection. The proposed structure is analyzed by the full-wave analysis of finite element method (FEM) and characterized experimentally. The results show that the return loss is more than 15 dB and the insertion loss is less than 0.5 dB in the frequency range from 2.5 GHz to 6.3 GHz. The proposed grounding scheme will be useful for the ground connection lot the microwave high density devices and module of 3D configuration.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.7
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• pp.24-30
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• 2000

In this paper, we proposed an fiber-optic transceivers based on the analog optical transmission techniques of incorporating the SCM (subcarrier multiplexing) and WDM (wavelength-division multiplexing ) method, which can be used to transmission of IMT-2000 and PCS wireless frequency band and analyzed overall those parameters related with fabrication. Especially in the impedance matching network between RF signal and LD, we proposed the method of deriving optimal performance using simulation techniques. In the frequency band of 1.7GHz∼2.25GHz, experimental data for the gain flatness and the noise floor of the optical link were also presented $\pm$1.5dB and -130dBm respectively when the link Rain was 0dB.