• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.960-966
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• 2018

Communication antennas used at sea have been developed remarkably. However, the speed of this development is insufficient when compared with user demands. Therefore, we developed an antenna for UWB/Bluetooth that operates on 3 [GHz] and 5.72 [GHz] bands in order to use the high-speed communication network system which improved antenna miniaturization, gain and radiation patterns. To improve bandwidth, a microstrip patch antenna was selected and CST Microwave Studio 2014 program was used. Through the program, we calculated the slot width, length, transmission line width, etc. using a theoretical formula at each step. These figures were checked through simulation to see if they meet production standards. UWB for high-speed wireless communication for short-range communication at sea, Bluetooth for exchanging information at a short distance by connecting each device, and corresponding technology can be easily utilized.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.665-669
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• 2018

In this paper, we design an antenna for LTE / Wi-Fi communication that operates in 2.65 GHz and 5 GHz band for small-sized broadband communication antenna that can be used in the sea. Microstrip patch antennas were chosen to improve the bandwidth. The slot width, length, and transmission line width were calculated using the theoretical formula for each step. In addition, we designed a microstrip antenna using CST Microwave Studio 2014 program that can design 3D. Simulation results show that the reflection lossis -12.712 dB at 2.65 GHz and -16.583 dB at 5 GHz. The gain was 1.738 dBi at 2.65 GHz and 3.284 dBi at 5 GHz. In this paper, we propose a dual-band antenna for LTE / Wi-Fi, which can be used in maritime environments, which is worse than terrestrial communication, because of differences in communication speed and communication stability compared with those used on land.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.856-867
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• 2018

This paper presents the applicability of MIMO joint decoding to dual-contact satellite systems in which two LEO satellites using X-band frequency band are transmitting each image data to two ground station antennas, simultaneously. When two satellites are closely positioned within the looking angle of the two antennas, each satellite interferes with each other by the relative antenna gain corresponding to an offset angle and this might cause the performance degradation without interference mitigation. To mitigate the performance degradation, SM MIMO techniques for joint decoding are applied. Especially, the relative antenna gain of ground station depending on the angle difference between two satellites in ground station antenna plays an important role in modelling the dual-contact satellite systems. The condition number of MIMO channel including the antenna gain calculated from the mathematical gain pattern model was primarily analyzed. Simulation results showed that the SM MIMO techniques using detection schemes such as ZF-SIC, MMSE-SIC, and ML can be applicable to dual-contact satellite systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1344-1349
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• 2012

The Korean DGPS station transmits the 200 bps GPS enhancement signal using the MSK modulation in frequency range of 283.5 kHz to 325 kHz. The land-based stations of 6 sites provide the service area of 80 km with the output power of 500 W. The ocean-based stations of 11 sites provide the output power of 300 W, which provide the DGPS service to 185 kM. Some places are serviced from two or three DGPS stations. The interferences among the DGPS stations using the high power can be occurred. Also, the performances of the user terminasl in dual service area can be degraded. In this paper, the protection ratios for the DGPS service are defined. Using the MF wave propagation model, the interferences among the DGPS stations and the adjacent wireless ground stations are analyzed. Also, the performances of DGPS user terminals are analyzed in the viewpoint of interference.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.7
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• pp.7-13
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• 2001

The wirebonding is a common interconnection technique for modern microwave devices because of rather simple and reliable processes involved. At millimeter-wave frequencies, however, the bondwire parasitics are significant and consequently limit the external performance of packaged devices. In this paper, we represent wideband characterization of multiple bondwires and ribbon in a frequency range from 20 to 35 GHz. From these results, the double bondwire shows very small insertion loss less than 0.55 dB up to 35 GHz and its performance is comparable to that of the ribbon in the millimeter-wave frequencies. Therefore, the wirebonding is very suitable for millimeter wave packaging in terms of performance and manufacturing cost.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.2 s.314
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• pp.18-23
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• 2007

Intra-body communication' is a wireless communication technology that uses a body as a transmission medium for electrical signals. Generally, an 'earth ground' is used to create an electric field for operating the system; however this operating method could not apply to telemetry for implanted neural prosthetic devices. So this paper suggests a newly designed intra-body communication for neural prosthetic devices. A floating system which has a couple of electrodes with body was studied to remove an influence of the 'earth ground'. We found that 10MHz is the most suitable carrier frequency in skin experiments and over 3MHz in subcutaneous experiments. The system has been applied to a current stimulator circuit for cochlear implant that uses pulse width modulation (PWM) method at 480kbps rate successfully.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.95-100
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• 2006

최근 반도체 기술과 무선 통신기술의 발전으로 센서 네트워크를 이용한 응용 분야가 다양하게 나타나고 있다. 본 논문에서는 센서 네트워크를 이용하여 산악지역의 자동인원계수시스템과 환경모니터링시스템을 개발했다. 이 시스템은 저전력으로 동작하고 이중 RF 보드를 이용하여 최대한 신뢰성 있는 데이터 전송이 가능하도록 개발하였다. 또한 산악지역에서 데이터 전송율과 통신 신뢰성을 만족시킬 수 있는 433MHz 대역이 적합함을 실험을 통하여 확인하였다. 기존의 CCD 카메라를 이용한 자동인원계수기는 전원공급과 네트워크 부재로 인하여 산악지역에서는 사용하기에 부적합하다. 본 논문에서는 산악지역의 탐방로 폭이 협소함을 이용하여 포토 빔 센서를 이용한 양방향 계수센서를 개발하였다. 산악지역에서 실험한 결과 1.5m 이하의 도로 폭에서 95% 이상의 계수 신뢰도를 보임을 확인할 수 있다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.7-18
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• 1999

We have designed and tuilt the quasioptical system for the dual channel receiver which is used for the simultaneous observation of the cosmic radio with 100GHz band and 150GHz band. The quasioptical system has been widely used to guide the beam for the millimeter and submillimeter waves. A Gaussian distribution of field and power transverse to their axis of propagation allow the simple and elegant theory of Gaussian quasioptics. Using the theory of Gaussian beam, we introduced the analysis of image beam which is applied for a wide range of frequency. In order to guide two beams from the Cassegrain antenna simultaneously, the quasioptical system and its components for the dual channel receiver were designed by using the image beam method. We have checked the characteristics of the quasioptical components and the system by using the heam measurement system, which is made by us. The quasioptical system has been installed in the dual channel receiver on the Cassegrain antenna. The performance of this system has been finally confimed through the successful simultaneous observation with two bands of the cosmic radio.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.211-218
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• 2007

Dual-polarization means to use two orthogonal polarizations, namely two independent channels in communication. This can be used to deal with high datarate caused by large amount of observed data in future LEO satellite. However, when two orthogonal polarizations are not perfectly independent to each other in practical, interference is probably raised in each channel, meaning that noise level in passband increases. XPD (Cross-Polarization Discrimination) is the ratio of the signal level at the output of a receiving antenna that is nominally co-polarized to the transmitting antenna to the output of a receiving antenna of the same gain but nominally orthogonal polarized to the transmitting antenna. In this paper, the influence of XPD on the communication between satellite and ground station was analyzed under the assumption that X-Band dual-polarization was applied to KOMPSAT-2 (KOrea Multi-Purpose SATellite-2). Through analysis, it was shown that more than 3dB of link margin was still achievable despite of worst axial ratio, 2.5dB, at ground station antenna when axial ratio of satellite antenna was about 0.5dB under 99% of environmental availability.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.72-75
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• 2012

In this paper, high-efficiency DC-AC converter is implemented for the wireless power transmission. The DC-AC converter is implemented by combining the oscillator and power amplifier. Because the conversion efficiency of wireless power transmitter is strongly affected by the efficiency of power amplifier, the high-efficiency power amplifier is implemented by using the Class-E amplifier structure. Also, because the output power of oscillator connected to the input stage of power amplifier is low, high-gain two-stages power amplifier using the drive amplifier is implemented to realize the high-output power DC-AC converter. The dual band harmonic suppression filter is implemented to suppress 2nd, 3rd harmonics of 13.56 MHz. The output power and conversion efficiency of DC-AC converter are 40 dBm and 80.2 % at the operation frequency of 13.56 MHz.