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A novel built-in phased-array calibration method for multi-stream 5G transceiver is presented. A transmit signal is monitored using couplers and sent to the receiver for the other stream. Multiple antenna elements are characterized simultaneously by solving linear equations using the proposed phase matrix which suppresses the required dynamic range. It takes less than 150 μs in loopback measurement to characterize gains and phases of 16 elements.

This paper presents a frequency-dependent in-phase and quadrature-phase (IQ) imbalance calibration technique for ultra-wide bandwidth 5G millimeter-wave communication chipsets. Using a multi-tone training signal and a phase shifter inserted in the transceiver local loopback path, the transmitter and receiver IQ imbalances can be estimated separately. The complex finite-impulse response filter introduced in this work compensates the spectrum flatness and the IQ imbalance concurrently and achieved an average image-rejection ratio of 51.6 dB over 1.4 GHz of bandwidth.

Time skew between inner line and outer line is main reason to induce differential to common-mode noise in differential bended lines. To compensate time skew arisen length difference of inner line and outer line, meander line structure was adopted. The increase of time delay for differential signal by mender line structure was verified by simulated results on balanced coupled transmission lines. The meander line structure, having four pair of section 1, and 2, or section 2, and 3 was adopted to inner line of right-angle bended line at both sides, and common-mode noises was reduced about 87 % of that induced by bended lines without meander line structure. From measured results, it was verified that S cd2 i were below 20-dB within range of 4 GHz both simulation and measurement, which means the time skew was compensated well with low differential insertion loss within range of 4 GHz both simulation and measurement. The length and width of meander line structure were only 1.2 mm and 1.75 mm, respectively, therefore, it has advantage of size miniaturization.

We demonstrate textile-based strain and pressure sensors using metal-nanowire embedded conductive fibers. The conductive fibers were fabricated by coating glycerol-doped poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonate) (G-PEDOT:PSS) and silver nanowires (Ag NWs) on nylon fibers. By using a commercially available sewing machine, textile-based strain and pressure sensors were fabricated on fabrics. The textile-based strain sensor showed high sensitivity (maximum gauge factor of ∼4) and reliability under applied mechanical strain of 5%, and also the pressure sensor showed reasonable pressure-responses to different levels of loading pressure.

This letter presents the design and measurements of a mm-wave phased array antenna for a 5G cellular system. The 1×4 planar array antenna consisting of vertical monopoles embedded in a dielectric substrate has been simulated and fabricated with waveguide-to-stripline transitions. The 3-dB beam widths are 30° and 90° for the H-plane and E-plane, respectively. The measured scanning performance with a 28 GHz RF test platform shows that the planar array antenna can steer from −90° to +90° taking into account of the 3-dB beam width.

This paper presents the utilization of the ADS Ptolemy system simulator for RF circuits and a ray tracing simulator for antenna and propagation, to compare performance of a given mmWave beamforming system of 28 GHz frequency band, 800 MHz bandwidth with different, i.e. 5°, 10°, and 20°, half-power beamwidth (HPBW) of base station antennas in outdoor-to-indoor propagation scenario. Simulation results in terms of delay profile, delay spread, frequency response, and overall system performance in terms of error vector magnitude (EVM) are shown and analyzed. The results show that the EVM of 5° HPBW case is significantly better than that of 10° and 20° HPBW cases. EVM is better than −23 dB for LOS positions. For NLOS positions where the direct signal is blocked by the concrete pillars or walls, thanks to the multiple reflections and beam steering, the received signal still secures EVM in most cases better than −15 dB.

The speed of the information flow propagation wave is a fundamental characteristic to analyze vehicle-to-vehicle (V2V) communications based traffic systems. It depends on the density of vehicles equipped with a V2V communication capability, the V2V communication constraints, and the traffic flow dynamics. This study proposes an integrated model consisting of integro-differential equations to describe the information flow propagation mechanism and a partial differential equation to describe the traffic flow dynamics. It can directly incorporate the success rate of communication with distance and interference as a probability density function, and provides a closed-form solution for the speed of the information flow propagation wave. Numerical simulation experiments are used to analyze the performance of the analytical solution. The results show that the analytical solutions are consistent with the average speed of the information flow propagation wave provided by the numerical experiments.

In this paper, we have presented chirp signal generation techniques using Field Programmable Gate Array (FPGA). FPGA based signal generation and signal processing modules are essential due to the requirement of high speed radar systems, and easy to compensate amplitude and phase distortions. The simulation and experimental results using Xilinx Virtex 6 FPGA are presented.

In this paper, we present the modeling, simulation and signal processing of Doppler radar for heart beat and reparation sensing. Distance dependency of accuracy of heart and respiration signal from radar output is investigated and verified through simulation. The model is experimentally validated with commercially available motion detector DNO-341. The based band signal containing respiration and heartbeat signatures are low-pass filtered (0.7 Hz) for the respiration and band-pass filtered (0.9–2.5 Hz) for the heart signal. The estimated heart beat per minute and peak-peak interval is verified with result obtained from standard ECG measurement.

Modeling the spatiotemporal propagation characteristics of information under vehicle-to-vehicle (V2V) communications is critical for developing information-enabled applications to improve traffic safety and mobility. Existing analytical approaches assume instantaneous information flow propagation to simplify the communication constraints arising from the traffic flow dynamics. Consequently, information flow propagation characteristics such as the information flow propagation wave have not been analyzed. They are necessary to describe the interactions with the underlying traffic flow dynamics. An analytical model, which integrates an epidemic model with a traffic flow model, is developed to account for such interactions. The proposed model is able to capture the dynamics of information flow and traffic flow in an integrated formulation that circumvents key analytical and numerical challenges. Results from computational experiments demonstrate the effectiveness of the proposed model and its ability to describe the dynamic characteristics of information flow propagation along with the traffic flow dynamics.

Amorphous indium gallium zinc oxide(IGZO) based thin film transistors(TFTs) have been widely studied due to their good electrical properties such as optical transparent and field effect mobility. The demand for low-cost process of thin film devices has needed solution processed metal oxide TFTs. Although many effective ways of fabricating soluble metal oxide TFTs have been investigated 1 , there is still the necessity of increasing field effect mobility of TFTs. As a one way of mobility improvement, low work function metals(Ca, Ti) were used as passivation in terms of capping layer on top of the IGZO active layer 2 , 3 . The metal capping method has obvious several advantages, but we expect the additional process cost due to a step of patterning the capping layer. Also, because nature of metals has no transparent characteristics, this pure metal capping method could not available in transparent applications. In this paper, we suggest a real time deposition method of electrodes and capping layer for solution processed IGZO TFTs with maintaining transparency and process cost.

The space borne X-band 2-axis gimbal antenna needs frequency re-uses techniques by dual circular polarization for the very high data transmission. The gimbal antenna consists of 2-axis driving mechanism, high efficient horn antenna, very low loss non-contact type RF transmission line of coaxial type rotary joint. This paper designed high efficient horn antenna and very low loss non-contact type RF transmission line of coaxial type rotary joint and 2-axis driving mechanism.

This paper describes the W-band fully polarimetric radiometer design and the measurement results of material's emissivity of rubber sheet and water as examples using developed radiometer. The measured brightness temperatures of sample materials depend on incident angle. For this angle dependent measurement, the test set-up was designed. Using the measured brightness temperature, the characteristics of material like emissivity and dielectric constant can be retrieved. Finally, the comparison between theoretical value and measurement value are also listed in the paper.

InP/ZnSe/ZnS muitishell colloidal quantum dots (QDs) with high quantum yield were prepared by convenient heating-up method for a light emission layer of transparent QD light-emitting diodes (QD-LEDs). The synthesized InP/ZnSe/ZnS multishell QDs exhibited an emission peak at 545 nm for clear green color with a full-width at half-maximum (FWHM) of 50 nm, and photoluminescent quantum yield (QY) of 40 %. Using a Ca/Ag cathode, the whole QD-LED device was semi-transparent and the maximum luminance and current efficiency reach 400 cd/m2, 0.80 cd/A.

In this paper, we developed and experimented of the W-band 1-D focal plane array (FPA) passive imaging radiometer which was called by Millimeter-wave Imaging Radiometer Equipment (MIRAE). This consists of quasi-optics including a dielectric aspheric lens and a metal mirror as a reflector, 30 channels FPA receiver based on the direct conversion type, scanner, image processor and displayer. To get 2-D radiometer image with 1 Hz frame rate, the radiometric 1-D FPA receiver is moved into one direction by the linear scanner. From the experiment results, it is certain that MIRAE system can get enough good outdoor radiometer images to detect concealed metal weapons under clothing in the short range application such as security, comparing with other commercial and competitive passive imaging radiometer systems at W-band.

This paper presents a new concept of the phase shifter design called a hybrid phase shifter. The proposed hybrid phase shifter consists of an analog-type active phase shifter and a digital-type passive phase shifter. To verify the idea the circuit is designed using 0.13-μm RF CMOS technology at 22–26-GHz UWB frequency band. The hybrid phase shifter has the continuous phase shift range up to 25.40, which is able to cover almost two times of the designed analog or digital phase shifter range. The gain drift of about −2.0 dB to 0.7 dB at 24-GHz is observed during phase shift. The simulation results confirm that the proposed hybrid phase shifter can be a good candidate as one of the phase shifter for the implementation in active phased array or multi-antenna beamforming system.

In target tracking, radar or sonar sensors provide amplitude information as well as kinematic information, e.g., range and bearing. Considering the amplitude information with kinematic information, tracker can more effectively distinguish measurement origin in cluttered environment. The tracker utilizes the amplitude information in the form of signal to noise ratio (SNR). However, a major challenge comes from the fact that the SNR is often fluctuated according to the target's aspect and effective radar cross section. So the certain level of uncertainty of SNR should be reduced. Focused on the point, we propose a novel SNR estimation algorithm based on sequential Monte Carlo method. Finally, estimated SNR is applied to the probability data association filter with amplitude information. Simulation results demonstrate the effectiveness and high accuracy of the idea of exploiting SNR estimation in heavy cluttered environments.

For the last few decades, microwave radiometers have played an important role in various remote sensing applications of the earth environment such as atmosphere, ocean and soil. Especially, various polarimetric emission for more accurate estimation. In general, the electromagnetic wave is represented as full Stoke parameters. [1] The Stoke parameters can be defined as the horizontal and vertical polarization for the first and second parameters, and the 45 degree linear and circular polarization for the third and forth parameters, respectively. [2] In this study, we developed the fully polarimetric radiometer to measure full Stokes parameter at 94GHz. For stable and high sensible Stokes parameters measurement, we implemented a wideband analog correlator and a total power type receiver with periodic calibration. In order to measure full Stokes parameters, it needs the calibration by using the additional polarized references. The fully polarimetric calibration standard is composed of a polarizing grid, a retardation plate, and reference sources. The characteristic of calibration standards was measured and evaluated.

The design method of calibration standard of fully polarimetric radiometer to measure the Stokes parameters at W-band is proposed. The information of 45 ° in a linear and a circular polarization are calibrated using the wire grid with thin Teflon substrate and the retardation plate which was implemented by dielectric plate with grove. The calibration standards show good performance on orthogonal channel polarization mixing (−17 to −25 dB), on mixing from the orthogonal channel into the polarimetric channels (−10.1 to −6.0 dB), and on mixing between polarization channels (−3.2 to −5.8 dB).

A 7.7mW/1.0ns/1.35V digital delay locked loop has been proposed in this paper. The dual-DLL architecture with racing operation is adopted to achieve low power operation and low jitter, which is primarily caused by the length of the delay line. The merged dual coarse delay line (MDCDL) is employed for low power and high frequency operation. This DLL utilizes an OR-AND DCC for wide duty cycle correction capability. The proposed DLL for DDR3 SDRAM is fabricated by a 54nm DRAM process technology. Experimental results show that ±10% duty error of external clock can be corrected in less than 400 cycles locking time with 1.0GHz operation frequency at 1.35V.

High resolution brightness temperature (BT) image of millimeter-wave radiometer is produced by mechanically scanning or by two dimensional antenna arrays for passive millimeter-wave (PMMW) range measurement. Similar to visible photogrammetry and stereo ranging, the range of target is estimated with stereo image pair taken by the radiometer. In this paper, we propose the range measurement method using 2-D scanning single radiometer for stereoscopic passive image. Two images are captured by scanning radiometer with baseline distance and range of the specific object can be determined by baseline distance with angular difference of an object from radiometric images. But there are many uncertainties for the range and range accuracy. We also have tested and analyzed this issue. In the experiment, range discrepancy effect dependent on target form of w-band scanning radiometer were tested and analyzed.

The W-band fully polarized radiometer with the detail calibration is presented. The calibration standard for the measurement of Stokes parameters was designed and the measured results are presented. For the calibration standard, a wideband analog correlator was designed and described the performance. The correlation coefficient of the U and V Stokes parameter was 0.92 and 0.96, respectively. The detail analysis of the error of the calibration is presented in terms of random and systematic uncertainty.

A size reduced waveguide orthomode transducer with a turnstile junction and two T-shaped power combiners is described. The X-band version orthomode transducer has been fabricated and measured. Lastly the measurement result was compared with simulation result and was analyzed with fabrication errors. From 9.2 to 12.4GHz, the input return loss was less than −18.5dB, the transmission loss was ∼0.2dB, the cross-polarization was less than −35dB, and the isolation between two channels (Horizontal, Vertical) was less than −36dB.

A passive millimeter wave (PMMW) imaging has been demonstrated at W-band using a single channel(1-Ch) receiver. As a first step of this experiment, a car at a distance of 3 m from the receiver was imaged by a fabricated 1-Ch receiver.

In this paper, a possibility of applying the method of auxiliary sources (MAS) in analyzing the characteristics of insulated wire antennas in layered media has been explored. The existing DGF-MAS technique for the analysis of bare antenna in layered media has been revisited and extended to analyze insulated antennas, which has been overlooked by other researchers. Numerical examples have been presented for several interaction problems to demonstrate validity, accuracy, and efficiency of the proposed technique. The proposed method can also be applied to the analysis of antennas immersed in arbitrary shaped insulation layer. Furthermore, analysis of the wire antenna with a spherically layered insulator which is eccentric to a spherically layered medium and more practical case of insulated antenna problem such as the wire antenna with a spherically layered insulator in a cylindrically layered medium, which models the wireless capsule endoscopy application roughly, is under investigation.

Dual-channel Radiometers for Earth and Atmosphere Monitoring (DREAM) is the Korean spaceborne microwave radiometer. It is the main payload of Science and Technology SATlleite-2(STSAT-2) and will start the mission in December 2008. In this paper, we describe the radiometric calibration of DREAM. We also present the performance results of the system-level.

In this paper, high spatial resolution imaging of a motion induced synthetic aperture radiometer with sparse rectangular array is presented. The imaging process is described including an observation scenario and image formation. The equivalent array factor and instantaneous spatial frequency coverage are presented to demonstrate the performance. Additionally, the differences between the proposed system and previous studies are discussed.

In this paper, we present the design and calibration of the fully polarimetric radiometer at 94 GHz. For stable and high sensible Stokes parameters measurements, we applied a wideband analog correlator and a total power type receiver with a periodic calibration. To perform the fully polarimetric calibration, a calibration standard was designed and tested. Using the calibration standard, the calibration gain-offset was estimated and evaluated. The measured sensitivities with the integration time of 10 ms are approximately 1.26 K and 1.27 K in the horizontal and vertical channels, respectively. Other performances of the developed system and the calibration are also described and discussed.

The design and characteristics of a Ka-band, magnetron based radar are described. Novel solutions used for the development of an electrically scanning slotted waveguide antenna array, a low noise digital receiver with a coherent on receiver technique implemented, and an advanced data acquisition and signal processing system are described. Possible applications of the radar are related to enhancing helicopter safety including detection of power lines and other obstacles, monitoring meteorological conditions on the direction of flight, and providing secure landing.

There has been much interest in accurate and fast numerical analysis of 1-D periodic planar structures. Recently the efficient method to obtain 1-D periodic Green's functions in planar structure was proposed (Baccarelli et al., 2006). Here we propose the efficient method for the evaluation of impedance matrix in applying the method of moment.

In this paper, a novel matching network for compact microwave amplifier is introduced. The concept is to minimize circuit area by combining the functions of dc block and impedance matching circuit with single distributed component. Suggested scheme is easier to extract parameters of matching circuit comparing previous work due to its reduced determinable parameters. Values of the proposed circuit are not only to miniaturize circuit area, but also to design analytically in conditionally stable amplifier with stability margin analysis. Since it could be adopted in any passive networks that contain dc block and impedance matching network simultaneously, application area would be wide in the microwave/millimeter-wave components.

The first Korean spaceborne microwave radiometer has been developed since 2004. Its name is the dual-channel radiometers for earth and atmosphere (DREAM). It is the main payload of the science and technology SATellite-2 that will be launched in 2008. Recently, the development and performance test of DREAM flight model (FM) was completed. This document presents the hardware specification and performance test results of DREAM FM.

In this work, ultrafine indium tin oxide (ITO) nanoparticle for ink jet printing was successfully developed by newly developed low temperature synthetic method at 300degC. Mean size of the synthesized ITO nanoparticle is 5 nm with very small deviation less than 10%. High specific surface area of 117 m2/g certifies the ultrafine particle size. Especially, the ITO nanoparticle was well dispersed by the surface additive. Despite of the low temperature synthesis at 300degC, ITO nanoparticle was well crystallized with (222) preferred orientation. Composition ratio of In and Sn is 90 and 10 wt% in the lattice of the ITO nanoparticle. Also, using the well dispersed ultrafine ITO nanoparticle, ITO ink was attempted to make for ink jet printing. As a result, ITO ink was made well by dispersing the ITO nanoparticle into the organic solvent uniformly. Using the nano ITO ink, ITO transparent thin film with high optical transmittance over 90% could be fabricated.

Carrying out first-principles density-functional and matrix-Green’s function calculations, we study the electron tunneling through self-assembled monolayers (SAMs) of conjugated n-alkene chains (n = 8, 12, 16, and 30) bridged to Au(111) electrodes via monothiolate and dithiolate contacts. In contrast to the semiconducting behavior of bulk polyacetylenes, we do not find any current decay up to 30-alkene chain length. Comparing tiholate and dithiolate cases, we observe only a small difference in their resistance (ratio of 2.8), or minor dependence of charge transport characteristics on the contacts. We thus predict that ideal nanoscale alkene chains can be a good wire component for molecular electronics.

This paper presents design and characteristics of a compact, highly integrated Ka-band T/R module built by using a miniature magnetron in the transmitter chain. By implementing a solid-state modulator and microstrip design in the microwave part of the receiver, the overall size of the module has been reduced significantly. The module provides capabilities to realize Doppler date processing by using a digital coherent-on-receiver technique.

This paper presents the application system of remote sensing which monitors urban objects. The system mainly aims to help public officials detect the changed areas using easy method and friendly user interface. The land cover images and the ortho-rectified aerial images which have been linked together by using geo-coordinates information are the main data to be imported and processed in the system. The modules in the system have consisted of land cover change detection and urban change detection. The latter one is for urban monitoring and planning, vector data update. Especially, urban change detection module is very useful to reduce workload of public officials performing aerial image interpretation. To be more specific, an image differencing technique and change vector technique in conjunction with transparency viewing function are employed to detect the candidates of changed area and object. Change vector technique is based on the concept of spectral angle difference of pixels in image space between co-registered images from two dates. A final product is an image layer indicating location where change occurred by overlaying of digital thematic map. We mainly present the procedure regarding change detection run by Link Viewer module.

A new robust M-beamformer is developed for estimating the angle, velocity, and range in impulsive noise environments using an active radar array with antenna switching. The proposed robust beamformer uses a nonquadratic loss function and is implemented as a recursive weighted least squares (LS) algorithm. A special power function of the proposed beamformer is derived by minimizing the absolute value loss function of estimation residuals. Maximum peaks of this power function are used for estimation of the angle, velocity, and range of multiple moving targets. Simulation demonstrates that the new robust L/sub 1/-norm beamformer offers a high accuracy in estimation of movement parameters and has a decreased sensitivity of the estimates with respect to noise components having heavy-tailed distributions.

The dual-channel radiometers for Earth and atmosphere monitoring (DREAM) is the main payload for the science and technology satellite-2 (STSAT-2) mission. This instrument is the first spaceborne microwave radiometer in Korea. It is a two-frequency, total power microwave radiometer with linear polarization. It operates at 23.8 GHz and 37 GHz for remote sensing of the Earth. In this paper, we present its system configuration and system design.

Dual-channel Radiometers for Earth and Atmosphere Monitoring (DREAM) is the Korean first spaceborne radiometer which is the main payload of Science and Technology SATellite-2 (STSAT-2). The satellite will be launched by Korea Space Launch Vehicle-1 (KSLV-1) at NARO Space Center in Korea in 2007. DREAM is a two-frequency, total power microwave radiometer with linear polarization. It measures the brightness temperature of the Earth at 23.8 and 37 GHz. In this paper, the characteristics and the preliminary design of DREAM are described.

We investigate the performance limits of a passive pico-cell system with an electroabsorption modulator (EAM) using the radio-over-fiber technique in a 2.4 GHz wireless local area network (WLAN) environment. WLAN signals from a wireless router can not be detected properly at the WLAN card even in a service range of 1 m for the zero bias voltage to the EAM. To overcome and understand the performance limits, we apply bias voltage to the EAM and vary the optical modulation index (OMI) of the transmitter. Power margins in the links are found to estimate a possible service range, and packet loss rates in the pico-cell system are measured to evaluate the transmission performance. The service range can be extended up to 3 m by applying bias voltage to the EAM or adjusting the OMI of the transmitter.

This work presents 60 GHz small mobile transceiver (SMT), with integrated IF modem, for millimeter-wave over fiber communication systems. In this system, the transceiver integrates a 60 GHz transmitter, receiver, and IF modem in one module. The system has the following characteristics: high data rate (155.52 Mbps), small size (130 mm/spl times/80 mm/spl times/3 mm), and pico-cell service area for wireless LAN or road-to-vehicle communication (RVC) in the intelligent transport system (ITS).

This article evaluates the performance of interferometric synthetic aperture radiometer using sub-Y-type array proposed by our research group, SSL at GIST, Korea. The proposed array type has an improved resolution than the conventional Y-type known as optimal array configuration in the design of 2-D interferometric radiometer. To evaluate it, the interferometric synthetic aperture radiometer with 40 antenna array is developed at 37 GHz and two target noise sources were used for performance test. Through the experiments, the performance evaluation shows 23% improvement of angular resolution than the conventional Y-type

We describe a radio-over-fiber (ROF) based ultra-wideband (UWB) transmission system. In a multi-cell environment using ROF technology, the performance of UWB signal transmission with different modulation schemes is evaluated in a realistic channel model based on a modified /spl Delta/-K model. Then, we investigate the effects of multipath interference and delay time at the overlapped area on the performance of UWB in terms of link margin and bit error rates. The performance of a RAKE receiver with maximal-ratio combining is also studied using the optical and wireless link analysis simulator, Photonics CAD.

In many physical communication systems, the channel noise is known through experimental measurements to be non-Gaussian with an essential impulsive phenomena. The performance of standard signal estimators degrades substantially in the presence of such impulsive ambient noise. New robust M-estimation techniques are developed for combating impulsive noise and interference in communication systems. Power functions of the proposed robust estimators are obtained by minimizing a nonquadratic residual function derived from the P.J. Huber's minimax robust estimation theory (see "Robust statistics", Wiley, 1981). Maximum peaks of the power functions are used for estimation of communication signals as well as direction-of-arrival (DOA). Simulation shows that the proposed robust techniques, the robust median and robust Huber estimators, offer significant performance gain over the conventional estimator, with the best results given by the robust Huber estimator.