• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.693-696
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• 2011

In this work, an exponentially tapered microstrip antenna was implemented using a resistive loading technique in order to suppress the internal reflections. The inductive loading was realized by introducing slits on the antenna to improve radiation efficiency. Compared with a resistive-loaded antenna, the proposed antenna had an average improvement of about 6.2% in radiation efficiency within the range of 2-10.5 GHz. In addition, the highest peak of the radiated short pulse from the proposed antenna became 45% greater than that of an antenna with resistive loading only.

• Journal of electromagnetic engineering and science
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• v.13 no.2
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• pp.104-112
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• 2013

A novel miniaturized artificial magnetic conductor (AMC) is proposed for dual-band operation. An AMC unit cell that employs four slots in the metallic patch is used to achieve miniaturization as well as easy control of the second/first resonant frequency ratio, which can be varied from 1.5 to 3.26 by simply changing the slot shape for a given metallic patch size. A dual-band antenna composed of a wideband monopole suspended over the proposed AMC surface is designed and tested to validate this approach. The measurements result in a satisfactory and good matching condition for the dual-band antenna.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.143-148
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• 2006

The goal of this paper is to analyze, through simulations and experiments, GNSS interference mitigation performance under various types of antenna structures against wideband and narrowband interferences using spatial-temporal adaptive signal processing (STAP) techniques. The STAP approach, which combines spatial and temporal processing, is a viable means of GNSS array signal processing that enhancing the desired signal quality and providing protection against interference. In this paper, we consider four types of 3D antenna array structure - Uniform Linear Array (ULA), Uniform Rectangular Array (URA), Uniform Circular Array (UCA), and the Single-Ring Cylindrical Array (SRCA) under an interference environment. Analytical evaluation and simulations are performed to investigate the system performance. This is followed by simulation GPS orbits in interfered environment are used to evaluate the STAP performance. Furthermore, experiments using a 2x2 URA hardware simulator data show that with the removal of wideband and narrowband interference through the STAP techniques, the signal tracking performance can be enhanced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.914-923
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• 2009

Helix antennas have been widely applied to satellite TT&C, data communication and GPS receiver systems onboard military, remote sensing and communication purpose satellites. The helix antennas are known to be convenient to control impedance and radiation coverage characteristics with a maximum directivity in satellite z-axis. Waveguide horn is commonly used for radar system that needs ultra-wideband pulse for exploration ground radar and electromagnetic disability measurement etc. It has high efficiency and low reflection characteristics provided by the low-profile shape and suppressed radiation distortion. In this paper, a waveguide horn structure incorporated with helix antenna design is proposed for satellite applications that require ultra-wideband pulse radar and high rate RF data communication link to ground station over wide coverage area. The main design concern is to synthesize variable beam forming pattern based on modified horn-helix combination helicone structure such that multi-mission antenna is implemented applicable for TT&C, earth observation, high data rate transmission. Waveguide horn helps to reduce the overall antenna structure size by introduction fold type reflector connected to the tapered helix antenna. The next generation KOMPSAT satellite currently under development requires high-performance precision attitude control system. We present an initial design of a hybrid hern-helix antenna structure suitable for efficient RF communication module design of multi-purpose satellite systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1098-1106
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• 2007

This paper presents active antenna diplexers implemented into an ultra-wideband CPW(Coplanar Waveguide) fed monopole antennas. The proposed active antenna diplexer is designed to direct interconnect the output port of a wideband antenna to the input port of two active(HEMT) devices, where the impedance matching conditions of the proposed active integrated antenna are optimized by adjusting CPW(Coplanar Waveguide) feed line to be the length of 1/20 $\lambda_0$(@5.8 GHz) in planar type wideband antenna. The measured bandwidth of the active integrated antenna shows the range from 2.0 GHz to 3.1 GHz and from 5.25 GHz to 5.9 GHz. The measured peak gains are 17.0 dB at 2.4 GHz and 15.0 dB at 5.5 GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1414-1416
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• 2016

In this paper, a SWB (Super-WideBand) dipole antenna with self-complementary structure is proposed for signal intelligence. The proposed antenna consists of a self-complementary dipole antenna and a tapered balun for balanced feeding. The measured -10 dB reflection bandwidth of the proposed antenna is more than 28:1 (0.73-20 GHz) and 3 dB axial ratio bandwidth is 3.25:1 (1.91-6.22 GHz) with RHCP (Right Hand Circular Polarization) at +z direction. The measured radiation patterns are omni-directional in lower frequency band and bi-directional in higher frequency band. The measured peak gain within -10 dB reflection bandwidth varies from 2.83 dBi to 7.66 dBi.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.2
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• pp.47-55
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• 2003

In this paper, the performance of DS-CDMA system with smart antenna is analyzed for different bandwidths (1.25MHz,5MHz) and different channel environments (rural, urban) in wideband multipath channel. For the analysis of smart antenna system, the vector channel having the spatio-temporal correlation is modeled as a time-variant linear filter in time, and each multipath is assumed as a reflective wave from only one direction (only one cluster) in space. Several multipath is within one chip are distingushed into each one and the strongest signal is selected, DS-CDMA system with smart antenna using wider bandwidth present better performance than that using narrow bandwidth. It is shown that the smart antenna is more effective in urban area when using 2D-RAKE receiver.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.766-772
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• 2012

In the present study, wideband microstrip monopole slot antennas which can be applied to the RF4CE Zigbee remote controller are designed. First I-shaped monopole slot antenna which has ${\lambda}g/4$ length at 2.45GHz is designed. In particular, a conducting via is used to connect the microstrip feed line and the ground plane surrounded with the etched slot for the bandwidth improvement. In order to reduce the antenna size, it is changed into L-shaped and T-shaped monopole slot antennas for which improve results of antenna performance are observed. In case of T-shaped monopole slot antenna, impedance bandwidth(VSWR<2) is about 3.32GHz, and also its radiation efficiency and gain is more than 90% and 2.1dBi respectively at whole operating frequency range. In particular, all of proposed monopole slot antennas have the end-fire radiations which has a maximum radiation power toward direction of open ends of monopole slots.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.630-632
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• 2016

In this paper, we propose a modified rhombus slot UWB(Ultra Wide Band) antenna with fork-shaped feeding structure. The proposed modified rhombus slot structure is eliminated upper and lower part of the basic rhombus slot shape to get ultra-wideband characteristics for UWB communication. Also, feeding structure is used to fork-shaped structure to get ultra-wideband characteristics. The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.4, and its overall size is $34mm(W1){\times}34mm(L1){\times}1mm(t)$, and its slot antenna size is $30mm(W2){\times}16.75mm(L3+L4)$. After the optimized process, the proposed antenna is fabricated and measured. Measured result. fabricated antenna satisfied -10 dB impedance bandwidth in UWB frequency band (3.1 ~ 10.6 GHz ). And measured results of gain and radiation patterns characteristics displayed determined for operating bands.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.484-487
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• 2014

In this paper, We describe antenna characteristics for efficiently detecting human signs using small, planar and low power antenna. Then we can measure biological signals including respiration, heart rate, blood pressure, and blood sugar, using UWB (Ultra Wide Band) pulses, while does not contact the human body. The antenna need stable and wideband impedance characteristic, because it use gaussian pulse signal. Usually it has trade-off between wideband impedance and gain. But we don't considered array type antennas because we want to need small size. Generally the antennas that classified as frequency independent satisfy our requirements. Frequency independent antennas include spiral, log-periodic, sinuous, and etc. These antennas are possible to have shape planar type. In this paper, We tested these kind antenna's characteristics in center frequency 5 GHz, Especially circular patch and sinuous antenna designed and analyzed.