• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.984-989
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• 2008

In this paper, we will design a 800MHz broadband antenna after a problem of the narrow bandwidth is improved. This multiple band antenna unifies the CDMA(Code Division Multiple Access), GSM(Global System for Mobile Telecommunication) and TRS(Trunked Radio System) band in the UHF band, and then it is possible at the shore base station or repeater as the commercial use. It used the duplex resonance effect it had the L-shared feeding structure which adds the U-slot. And it improved profit using stack structure. It was measured that the frequency bandwidth of the designed antenna which is planed $792{\sim}1040MHz$ with 248MHz(33%). And the antenna gain is 9.4dBi, 3dB beam width $60^{\circ}$ in radiation pattern.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2210-2216
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• 2007

In this paper, triple-band plastic chip antennas for mobile terminal are investigated. Plastic chip antenna is composed of Foamex material with circle of PVC(Polyvilyl chloride). For its electric characteristics, the dielectric constant is 1.9, the insulation intensity is 112KV/cm. Plastic chip antennas are don't tend to break easily against to external shock, have more gain and efficiency than ceramic chip antennas. Triple-band plastic chip antennas of four type are implemented and experimented. From the experiments results, the antenna resonate at the triple-band, the gain of the antennas has about above -2dB, the pattern is ommidirectional the same as the conventional antennas. So, the antennas realized with Foamex material will be application for mobile phone antenna operated at the triple band which is cellular band and Korea-PCS band and ISM band or the antenna for other wireless communication system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.103-108
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• 2023

In this paper, a performance enhancement study of an AESA antenna that can be applied to a seeker that serves as the eye of a missile was conducted, and the performance of the antenna was verified through actual measurement. When designing an AESA antenna, the optimization of the active reflection coefficient must be considered during transmission due to the mutual coupling between radiators that inevitably occurs, and the selection of a radiator that can overcome the space limitation of the seeker with a small size/light weight is an important design consideration. Accordingly, optimization in terms of electrical performance and low-profile structure is required through research on array antennas for application to the AESA structure. The radiator designed and measured in this paper was designed as an SFN that can satisfy the low-profile structure while enhancing the performance of a general vivaldi antenna. Through this paper, it was confirmed that SFN has the same broadband characteristics as general vivaldi antennas and has optimized characteristics required for AESA antennas. The structure optimized through simulation confirmed the pattern characteristics and active reflection coefficient characteristics through the fabrication of actual proto-type antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.336-344
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• 2011

The purpose of this study is to analyze the radiation-pattern characteristics above 1 GHz for the electromagnetic wave radiated from multi-slot such as ventilations, etc. on the enclosure of an EUT and so to make recommendations for suitable test methods. An experimental EUT was formed by putting a comb-generator at the center of a rectangular enclosure with 4 slots, and its radiation pattern was analyzed in the frequency range of 1~6 GHz. As analysis results, multi-lobe appears above 2 GHz and the number of multi-lobes is growing as the frequency increases. And real radiated-emission measurements were performed for the experimental EUT by scanning a receiving antenna in the height of 1~4 m and tilting toward maximum radiation, as well as setting the height of a receiving antenna to the central position of the EUT which is prescribed at the present standards. The measured results are +12.8 dB in the scanning and +16.4 in the scanning and tilting compared with the present standard test method. Therefore, the latter must be revised in order to consider the radiation pattern above 1 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.8
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• pp.759-764
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• 2004

This paper proposes a method that estimates MIMO channel characteristics analytically using a 3D ray tracing propagation model. We calculate the discrete spatial correlation between sub-channels by considering phase differences of paths, and using this, estimate the mean capacity upper bound of MIMO channel by Jensen's inequality. This analysis model is a deterministic model that do not approach stochastically through measurement nor approach statistically through Monte-Carlo simulations, so this model has high efficiency for time and cost. And based on the electromagnetic theory, this model may analyze quantitatively the parameters which can affect the channel capacity - antenna pattern, polarization mutual coupling, antenna structure and etc. This model may be used for the development of an optimal antenna structure for MIMO systems.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.132-137
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• 2010

We present results of room-temperature characterization of lithographically manufactured antenna-coupled NbN micro-bolometers. The bolometers are assembled together with a hyper-hemispherical Si lens to couple the incident radiation to the bolometer from the back-side of the substrate. The bolometers are designed to operate at 300~1,000 GHz and they are characterized at 321~782 GHz. Radiation patterns are measured at 321 GHz, 400 GHz, 654 GHz, and at 782 GHz. The frequency dependency of the beamwidth is studied with several azimuthal beam profile measurements at 321~500 GHz.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.3
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• pp.1-12
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• 2004

When a straight-in landing from an instrument approach using ILS or VOR/DME is not possible or desirable because of topographical reason or bad weather, a circling approach maneuver is initiated by the pilot to align the aircraft with a runway for landing. Visual contact with the runway is necessary while conducting a circle to land maneuver. This research is to develop a new warning system based on a conventional marker system which alerts pilots to watch out for exceeding the circling approach area. The airborne system also uses the same receiver unit without any new installations. The objective of this research is to design and develop a Yagi antenna in a special form. The research includes computer simulations to determine the size of antenna radiation pattern and to compute an expected flight path in case of alarm to validate effectiveness of the system.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.199-205
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• 2018

In this study, an imaging mode of the modified SweepSAR is proposed with performance analysis for a high-resolution and wide swath coverage. To reduce the overall antenna size required for the solution of the azimuth ambiguity problem, different pulse repetition frequencies (PRFs) are utilized for different transmitters, respectively. For each imaging mode, system performance parameters are used for simulation, analysis, wide swath prediction, and comparison between conventional ScanSAR mode and SweepSAR mode based on scanon-receive (SCORE). The system parameters of AASR, RASR, and NESZ will be estimated and suggested on the imaging mode by using appropriate reflector antenna with the effectiveness of a modified SweepSAR employing dual channels.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.5 no.1
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• pp.25-36
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• 2006

This paper discusses the implementation and performance evaluation of a DSP-based digital beamformer using the Texas Instrument TMSC6711 DSP processor for smart antenna applications. Two adaptive beamforming algorithms which served as the brain for the beamformer, the Normalized Least-Mean-Square (NLMS) and the Constant Modulus Algorithms (CMA) were embedded into the processor and evaluated. Result shows that the NLMS-based digital beamformer outperforms the CMA-based digital beamformer: 1)For NLMS algorithm, the antenna steers to the direction of the desired user even at low iteration value and the suppression level towards the interferer increases as the number of iteration increase. For CMA algorithm, the beam radiation pattern slowly steers to the desired user as the number of iteration increased, but at arate slower than NLMS algorithm and the sidelobe level is shown to increases as the number of iteration increase. 2) The NLMS algorithm has faster convergence than CMA algorithm and the error convergence for CMA algorithm sometimes is subject to misadjustment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.305-311
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• 1999

In this paper, it is designed a new type single layer patch antenna which is printed on a very thin film and separated from the ground-plane by foam with a low permitivity of 1.06 and a high thickness of around quarter wavelength. It allows the use of three-dimensional transition, from one level to another, so that its bandwidth can be enhanced by wideband impedance matching. The radiation pattern, return loss, and VSWR of the antenna are calculated using "IE3D" simulation package, and compared with the experimental results. Experimental results show that the bandwidth is about 65% of center frequency 6.8 GHz, return loss and VSWR are in a fairly good agreement with the calculations.culations.