• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1138-1146
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• 2005

This paper makes a study of a formulation of net filter discrimination(NFD) and its computation for analyzing adjacent channel interference and suggests a systematic algorithm for calculating protection ratios of co-channel and adjacent channel applicable to frequency coordination in the fixed radio relay networks. It is shown that adjacent channel protection ratio can be derived from two factors: One is NFD depending upon receiver filter characteristic as well as transmitter spectrum mask and the other is co-channel protection ratio given by a function of fade margin, modulation scheme, and allowable interference. Actually to show the computing procedure from transmitter spectrum mask and receiver filter characteristic, NFD has been obtained for channel bandwidth of 29.65 and 40 MHz at 6.2 and 6.7 GHz band, respectively. According to the results, NFDs at the first adjacent channel of 29.65 and 40 MHz provide 27.4 and 28.9 dB, respectively. From these data, adjacent channel protection ratios corresponding to each channel bandwidth yield 47.5 and 46.3 dB for a given 64-QAM and 60 km. The proposed method gives some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter radio relay networks.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.1
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• pp.42-52
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• 2012

In this paper, a waveguide antenna is designed and fabricated for side and rear radar sensor of vehicles in UWB (Ultra Wide Band) high band (center frequency : 9.5 GHz, -10 dB bandwidth : 600 MHz (6.4 %)). For the radar antenna, a probe fed rectangular waveguide antenna having simple structure and wide bandwidth is used. An important performance factor in this antenna is the isolation between transmitting (TX) and receiving (RX) waveguide antennas because this radar system uses TX and RX antennas separately. Thus the isolation between two antennas was simulated for E-plane and H-plane array. As a result, it was verified that the isolation of the H-plane array of the antennas is better than E-plane array, due to the TE10 mode. Therefore, H-plane arrayed waveguide antennas were mounted on a T-shaped radar module and performance of antennas was investigated. The -10 dB bandwidth of the TX and RX antenna mounted on T-shaped radar module was measured as 1000 MHz (10.52 %) and 1090 MHz (11.47 %) respectively and the isolation is less than -50 dB in the operation band. The peak gain is 7.65 dBi for the TX antenna and 7.26 dBi for the RX antenna and the beamwidth of H-plane of TX and RX antenna was measured as $64^{\circ}$ and $65^{\circ}$ respectively. Consequently, we verified that the proposed waveguide antenna is appropriate for a vehicle radar applications.

• Journal of IKEEE
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• v.14 no.1
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• pp.65-74
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• 2010

The Digital TV(DTV) standard has ushered in a new era in TV broadcasting and raised a great demand for DTV tuners. There are many challenges in designing a DTV tuner, of which the most difficult part is the frequency synthesizer. This paper presents the design of a frequency synthesizer for DTV Tuners in a $0.18{\mu}m$ CMOS process. It satisfies the DTV(ATSC) frequency band(54~806MHz). A scheme is proposed to cover the full band using only one VCO. The VCO has been designed to operate at 1.6~3.6GHz band such that the LO pulling effect is minimized, and reliable broadband characteristics have been achieved by reducing the variations of VCO gain and frequency step. The simulation results show that the designed VCO has gains of 59~94MHz(${\pm}$17.7MHz/V,${\pm}$23%) and frequency steps of 26~42.5MHz(${\pm}$8.25MHz/V,${\pm}$24%), and a very wide tuning range of 76.9%. The designed frequency synthesizer has a phase noise of -106dBc/Hz at 100kHz offset, and the lock time is less than $10{\mu}$sec. It consumes 20~23mA from a 1.8V supply, and the chip size including PADs is 2.0mm${\times}$1.8mm.

• Geophysics and Geophysical Exploration
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• v.15 no.1
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• pp.16-22
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• 2012

In this study, we setup a ground-based scatterometer using an antenna of which the center frequency is 9.5 GHz (X-band), and measured radar backscatterings from air/ice and ice/water interfaces to extract ice thickness. Both of air/ice and ice/water interfaces make strong radar backscatterings and so we can clearly identify two peaks in measured data by scatterometer. By using the distance of two peaks and refractive index of ice, we confirmed that it is possible to measure ice thickness. Field survey was performed at the downstream of Jiam River flowing into Chuncheon Lake. We measured radar backscattering from river ice along a survey path and extracted ice thickness. The ice thickness map of the downstream of Jiam River was produced by using kriging which is one of well known interpolation methods. The ice thickness was about 50 cm along the mainstream while ice was thin as 30 ~ 40 cm at a fast-flowing meander. Ice thickness was particularly thinner at some locations than that of surrounding areas even in the mainstream region of constant flow. This was because of impurities in ice or artificially formed refrozen holes after fishing. We expect that this study helps to expand utilization field of X-band SAR and airborne scatterometer system.

• Korean Journal of Remote Sensing
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• v.23 no.2
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• pp.137-144
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• 2007

In KORDI (Korea Ocean Research and Development Institute), the KOSC (Korea Ocean Satellite Center) construction project is being prepared for acquisition, processing and distribution of sensor data via L-band from GOCI (Geostationary Ocean Color Imager) instrument which is loaded on COMS (Communication, Ocean and Meteorological Satellite); it will be launched in 2008. Ansan (the headquarter of KORDI) has been selected for the location of KOSC between 5 proposed sites, because it has the best condition to receive radio wave. The data acquisition system is classified into antenna and RF. Antenna is designed to be $\phi$ 9m cassegrain antenna which has 19.35 G/T$(dB/^{\circ}K)$ at 1.67GHz. RF module is divided into LNA (low noise amplifier) and down converter, those are designed to send only horizontal polarization to modem. The existing building is re-designed and arranged for the KOSC operation concept; computing room, board of electricity, data processing room, operation room. Hardware and network facilities have been designed to adapt for efficiency of each functions. The distribution system which is one of the most important systems will be constructed mainly on the internet. and it is also being considered constructing outer data distribution system as a web hosting service for offering received data to user less than an hour.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.3
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• pp.210-219
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• 2005

We report on a low-cost V-band wireless transceiver with no use of any local oscillator in the receiver block using a self-heterodyne architecture. V-band millimeter-wave monolithic IC (MMIC) modules were developed to demonstrate the wireless transceiver using coplanar waveguide (CPW) and GaAs PHEMT technologies. The MMIC modules such as the MMIC low noise amplifier (LNA), medium power amplifier (MPA) and the up/down-mixer were installed in the transceiver system. To interface the MMIC chips with the component modules for the transceiver system, CPW-to-waveguide fin-line transition modules of WR-15 type were designed and fabricated. The fabricated LNA modules showed a $S_{21}$ gain of 8.4 dB and a noise figure of 5.6 dB at 58 GHz. The MPA modules exhibited a gain of 6.9 dB and a $P_{1dB}$ of 5.4 dBm at 58 GHz. The conversion losses of the up-mixer and the down-mixer module were 14.3 dB at a LO power of 15 dBm, and 19.7 dB at a LO power of 0 dBm, respectively. From the measurement of V-band wireless transceiver, a conversion gain of 0.2 dB and a $P_{1dB}$ of 5.2 dBm were obtained in the transmitter block. The receiver block showed a conversion gain of 2.1 dB and a $P_{1dB}$ of -18.6 dBm. The wireless transceiver system demonstrated a successful data transfer within a distance of 5 meters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.179-179
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• 2009

This is for the electrical characterization by IDC pattern using BST$(Ba_{0.5}Sr_{0.5}TiO_3)$ thin film. BST materials had been chosen for high frequency applications due to it's high permitivity and tunability. The BST thin films have been deposited on $Al_2O_3$ Substrates by Nd-YAG pulsed laser deposition with a 355nm wavelength at $700\;^{\circ}C$. The post deposition annealing at $750^{\circ}C$ in flowing $O_2$ atmosphere for 1 hours. The capacitance of IDC patterns have been measured from 1 to 10 GHz as a function of electric field ($\pm40$ KV/cm) at room temperature using inter-digital Au electrodes deposited on top of BST. The IDC patterns have three type of fingers number. For the 10 pairs finger was the best capacitance onto $Al_2O_3$ substrate. The capacitance was 0.9pF. Also Dielectric constant was been 351 at 100 mTorr and annealing temperature $750^{\circ}C$ for 1 hour. The loss tangent was been 0.00531.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.58-62
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• 1999

We fabricated a new hairpin type HTS 2-pole microstrip Bandpass filter to operate at 5.8GHz. The fabrication method was pulsed laser deposition and YBCO films were deposited on ${\alpha}$-A1$_2O_3$ substrates with a CeO$_2$ thin layer as a buffer layer. We developed a new style hairpin type filter by using interdigitide innerpole. Compared to the saute size regular hairpin type filters, our filter had a lower center frequency, bandwidth and loss by an amount of 14.5%, 29.6%, 0.5488dB, respectively. The size of the filters were 13.7${\times}$3.3mm. We did simulations on the several types of band pass filters by using HFSS and serenade. We measured growth rate and Tc of YBCO films grown on CeO$_2$/ ${\alpha}$-A1$_2O_3$ substrates which were rotated while growing films.

• ETRI Journal
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• v.29 no.4
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.55-58
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• 2001

In this paper, we present the results of the design and fabrication of the VCO(Voltage controlled Oscillator) using RF circuit simulator GENESYS and electromagnetic field simulator EMpower Frequency range is fabricated VCO is 850 MHz ~ 950 MHz, which is used Colpitts Circuit. the fabricated VCO is consisted of resonator, oscillator and MSL(Microstrip Line) is used in LC tuning circuit.(operated by negative feedback) MSL(Microstrip Line), Varactor(Plastic package), low noise TR(SOT-23), chip inductor(1608), chip capacitor(1005), chip resistance(1005). 1005 type is used for sample fabrication of VCO. In the fabrication process, circuit pattern is screen printed on the alumina substrates of over 99.9% purity. Center frequency of the sample VCO is 850MHz at $V_T=1.5V$, while the simulated value was 1.0GHz at $V_T=1.5V$. Variable frequency range of the sample is 860~950MHz in contrast to the 1068~1100MHz of the simulated values.