• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.95-102
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• 2006

In this paper, we model a traffic of multiple tags operated in 2.45GHz band RTLS environment and analyze the multi-tag interference. Also, we propose a high precision location estimation algorithm of RTLS and then analyze its performance. From the results, the BER performance of RTLS degrades as the number of multi-tags increase in Gaussian noise and fading(m=15) environment. To meet the BER specification of RTLS, $10^{-5}$, we have to limit the multi-tag number to below 40. We also estimate the tag's location in $250m{\times}250m$ searching-area with enhanced TDOA scheme. It is confirmed that the 3m radius within accuracy of RTLS specification is satisfied, if the number of sub-blink receives more than 2 when available reader is 3 to 8.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2461-2468
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• 2015

Sinuous antenna is utilized in a number of application like direction-finding system that require ultra wideband, but because of high input impedance of the antenna, it is difficult to design low-profile antenna and balun. In this study, we used Babinet's principle and proposed linear 2-arm slot sinuous antenna that is divided sinuous 6 cell with equal spacing between the most largest radius $R_1=31.83mm$ and the smallest radius $R_p=1.7mm$ instead of exponential 2-arm strip sinuous antenna for 2-18[GHz] frequency band to obtain low input impedance, and we have studied -10dB bandwidth of antenna when has been fed by $80{\Omega}$ instead of $188{\Omega}$ at feeder point. As a result, we have obtained return loss below than -10dB for about 4-18[GHz] frequency range in the case of slot antenna, but at all frequency band, return loss was above -10dB in the case of strip antenna.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.1
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• pp.27-32
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• 2015

In this paper, a mushroom typed electromagnetic band gap (EBG) structure to be inserted in the printed circuit board (PCB) inner layer in order to stabilize the PCB power line is proposed for global-navigation satellite service (GNSS). In designing the proposed EBG structure, the target stop-bandwidth was designed from 1.55GHz to 1.81GHz including GNSS and mobile communication-related frequency bandwidth. In this bandwidth, the insertion loss(S21) was observed below about -40dB. From the simulation results, it is expected that the stabilization of power delivery network (PDN) structure in the PCB circuit design should be improved and the effective correspondence to EMI will be helpful.

• 전자공학회논문지 IE
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• v.44 no.2
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• pp.1-7
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• 2007

The increasing high frequency capabilities of CMOS have resulted in increased RF and analog design in CMOS. Design of RF and analog circuits depends critically on device S-parameter characteristics, magnitude of real and imaginary components and their behavior as a function of frequency. Utilization of scaled high performance CMOS technologies poses challenges as concerns for reliability degradation mechanisms increase. It is important to understand and quantify the effects of the reliability degradation mechanisms on the S-parameters and in turn on small signal model parameters. Various physical effects influencing small-signal parameters, especially the transconductance and capacitances and their degradation dependence, are discussed in detail. The measured S-parameters of H-gate and T-gate devices in a frequency range from 0.5GHz to 40GHz. All intrinsic and extrinsic parameters are extracted from S-parameters measurements at a single bias point in saturation. In this paper we discuss the analysis of the small signal equivalent circuits of RF SOI MOSFET's verificated for the purpose of exacting the change of parameter of small signal equivalent model followed by device flame.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.1002-1008
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• 2001

The absorbing structure composed of multi-layered fiber reinforced composite materials was designed and microwave absorbing properties are investigated. On the basis of transmission line theory, the theoretical equations to predict the reflection loss and the appropriate composite material for each functional layer are suggested. The most significant result of this study is the successful design and fabrication of triple-layered composite laminates which has the superior microwave absorbing porperties (more than 10 dB in 4∼12 GHz range), without using the ferrite filler in the impedance transforming layer. In the two-layered composite laminate (absorber/substrate), however, the use of ferrite filler (about 40 wt %) in the absorbing layer is necessary to obtain the certain level of microwave absorbance. By combining the glass-fiber composite with ferrite filler and carbon-fiber composite substrate, the microwave absorbing properties more than 10 dB in 4∼12 GHz frequencies than be obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.379-388
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• 2007

This paper presents a real-time respiration and heartbeat detector comprised of a 1.6 GHz single-channel Doppler sensor and analog/digital signal processing block for remote vital sign detection. The RF front end of the Doppler sensor consists of an oscillator, mixer, low noise amplifier, branch-line hybrid and patch antenna. We apply artificial transmission lines(ATLs) to the branch-line hybrid, which leads to a size reduction of 40 % in the hybrid, while its performance is very comparable to that of a conventional hybrid. The analog signal conditioning block is implemented using second order Sallen-Key active filters and the digital signal processing block is realized with a LabVIEW program on a computer. The respiration and heartbeat detection is demonstrated at a distance of 50 cm using the developed system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.209-216
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• 2003

We design and fabricate slot array antenna for BMWS(Broadband Multimedia Wireless System) applications. This paper presents a simple feed structure, which consists of two horns and a parallel-plate waveguide, because antennas operating at 40.5 GHz~43.5 GHz have considerable feeding losses. The simple feed structure has the advantages of high-efficiency and mass-production. The fabricated antenna has a gain of 25.8 dBi with a sidelobe level below -18 ㏈ and a 3 ㏈ beamwidth of approximately 3$^{\circ}$ in the E-plane. In case of H-plane, a 3 ㏈ beamwidth is 17$^{\circ}$ and a sidelobe level is suppressed to below -27 ㏈. The experimental results are in good agreement with the simulation results. The authors expect that narrow 3 ㏈ beamwidth is obtained by combining a few proposed slot array antennas in parallel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.985-991
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• 2008

This paper presents a novel balanced mixer receiver front-end design based on a metamaterial structure applicable to differential-/common-mode excitation. This metamaterial structure functions as a leaky-wave antenna and provides in-trinsic common-mode suppression. Low LO leakage and high RF to LO isolation are achieved without additional filters for LO and RF paths. The metamaterial is based on a unit-cell which under a differential-mode excitation behaves like a composite right/left-handed(CRLH) metamaterial. In contrast, the metamaterial unit-cell is below cut-off under a common-mode excitation. Experimental results are used to verify the proposed metamaterial's differential-/common-mode characteristics. The metamaterial is integrated with a balanced mixer design resulting in an operation frequency range of $1.96{\sim}2.40$ GHz with an optimum mixer conversion loss of 21.1 dB at 2,4 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.653-659
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• 2016

This paper proposes an ultra-wideband Log-Periodic Dipole Array(LPDA) antenna for the feeder of a reflector antenna to be used for airborne spinning direction-finding and detecting wideband signals. To obtain the ultra-wideband characteristics over the 20:1 bandwidth from S to Ka band, the radiation elements of the antenna were printed on a substrate and a wedge-typed dielectric supporter with robust structure was inserted between the substrates. Also, the center portion of the supporter was replaced by a styrofoam material to reduce the supporter weight. The 5-dB return loss of the designed LPDA antenna showed ultra-wideband characteristics, which are 37.57:1(1.09~40.95 GHz) in the simulation and 33.85:1(1.31~44.35 GHz) in the measurement. We achieved the required gains of 5.78 dBi in the simulation and 5.76 dBi in the measurement in the operating band. The proposed robust, light-weight, and ultra-wideband LPDA antenna confirmed that it can be applied for airborne applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.964-969
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• 2007

A regulated low phase noise differential colpitts VCO(Voltage Controlled Oscillator) for mobile RFID system is presented. The differential colpitts VCO meets the dense reader environment specifications. The VCO use a $0.35{\mu}m$ technology and achieves tuning range $1.55{sim}2.053 GHz$. Measuring 910 MHz frequency divider output, phase noise performance is -106 dBcMz and -135dBc/Hz at 40 kHz and 1MHz offset, respectively. 5-bit digital coarse-tuning and accumulation type MOS varactors allow for 28.2% tuning range, which is required to cover the LO frequency range of a UHF Mobile RFID system, Optimum design techniques ensure low VCO gain(<45 MHz/V) for good interoperability with the frequency synthesizer. To the author' knowledge, this differential colpitts VCO achieves a figure of merit(FOM) of 1.93dB at 2-GHz band.