• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.833-839
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• 2011

This paper has suggested a technique for measuring VSWR at 1.8 GHz band for various modulated signals. By using directional coupler the power of incident and reflected wave is measured, and in order to minimize the size and cost of the measuring circuit, a SPDT(Single Pole Double Throw) switch is adopted to realize the circuit with just one detector and one A/D(Analog to Digital) converter. MCU(Micro Control Unit) is used to calculate the voltage reflection coefficient and VSWR, and the measured VSWR error has improved by approximately 0.2 with applying a simple bubble sorting algorithm to reduce the measurement error, the MCU process time and load.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1374-1379
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• 2003

In this paper, twoㆍstage low noise amplifier(LNA) for 24㎓ is designed and fabricated using NE450284C HJ-FET of NEC CO. In order to get noise figure and input VSWR to be wanted it is considered input VSWR and noise figure simultaneously in matching-circuit designing. The fabricated two-stage low noise mph u has the gai of 16.6㏈, input VSWR of 1.6, and output VSWR under 1.5.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1455-1461
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• 2000

There are many researches to increase bandwidth of the microstrip patch antenna for wireless LAN. In spite of broad bandwidth, Bow-Tie antenna has disadvantages that are low gain and big size. In this paper, stacked Bow-Tie microstrip patch antenna for wireless LAN is designed in 5.725 ~5.825 GHz band. This antenna has characteristics that are broadband bandwidth, high gain and small size compared with microstrip patch antenna. In simulated results, the return loss is -34.2 dB at 5.78 GHz and bandwidth is 11.345% for VSWR 2:1 and 7.75%for VSWR 1.5:1. In measured results, the return loss is -38.45 dB at 5.78 GHz and bandwidth is 13% for VSWR 2:1 and 5.6% for VSWR 1.5:1. It has 73.16$^{\circ}$ -3dB beam width and 6.5dB gain.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.9 s.339
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• pp.65-70
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• 2005

For the base station or repeater which is in operation as part of a mobile communication system, any kind of degradation in antenna performance such as lowered gam or increased VSWR which maybe due to aging of antenna, connector corrosion or other environmental factors, is difficult to detect and react to immediately. In this paper, a VSWR measurement device which is capable of detecting the VSWR of a PCS forward path ($1,840\~1,870$MHz) antenna in operation in real time without any interruption in service is developed. Such regular measurement will allow the prediction of any serious failures and insure reliable operation of the antenna. All components of the antenna VSWR measurement device was researched so that the whole system could be produced and shown to be accurate in measuring the YSWR of an actual RF repeater in operation, proving it's effectiveness.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.176-183
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• 2004

In this paper, two-stage low noise amplifier(LNA) for S-band is designed and implemented using ATF54143 HEMT of HP CO. In order to get noise figure and input VSWR to be wanted, it is considered input VSWR and noise figure simultaneously in matching-circuit designing. The fabricated two-stage low noise amplifier has the gain of 27.8dB, input VSWR and output VSWR under 1.5.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.965-971
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• 2001

In this paper, the triangular u-slot patch antenna for the PCS & IMT-2000 dual band are studied. The frequency bandwidth of a triangular u-slot patch antenna can be increased by L-strip fed structure. The impedance bandwidth(VSWR$\leq$2) of the fabricated single element is 590 MHz(30.18 %). Using the frequency bandwidth of PCS & IMT-2000, we confirm VSWR below 1.65, which is a good characteristic. Thus the wideband characteristic of the L-strip fed structure is confirmed experimentally.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.146-149
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• 2000

SiGe HUT뜰 이용하여 Cellular 주파수 대역(824-849 MHz)에서 MMIC 상향 주파수 혼합기와 가변이득 증폭기를 설계하였다. 동작 전압은 2.7 V 이며, 이중평형 구조의 상향 주파수 혼합기는 12 dB의 변환이득, -0.6 dBm의 1dB 이득압축 출력전력, 30 dB 이상의 LO-RF 단자 격리도 특성, 1.25의 LO-VSWR. 1.34의 RF-VSWR을 가지며, 상호컨덕턴스형 가변이득 증폭기는 35 dB의 최대 선형이득, 13 dBm의 1dB 이득압축 출력전력, 42dB의 가변이득, 23dB의 3차 상호변조 교점 출력전력(OIP$_3$), 1.27의 입력 VSWR, 1.1의 출력 VSWR 특성을 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.304-308
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• 2003

In this paper, two-stage low noise amplifier(LNA) for 24GHz is designed and fabricated using NE450284C HJ-FET of NEC CO. In order to get noise figure and input VSWR to be wanted, it is considered input VSWR and noise figure simultaneously in matching-circuit designing. The fabricated two-stage low noise amplifier has the gain of 16.6dB, input VSWR of 1.6, and output VSWR under 1.5.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.998-1009
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• 1999

In this paper, a microstrip aperture-patch antenna and a microstrip ring antenna, which have single microstrip line feeding systems for the circular polarization, are designed, and experimental results are presented at X-band. The microstrip aperture-patch antenna is characterized by its wide operating frequency range, and the microstrip ring antenna is suitable for a basic radiator in the large array antenna due to its small size. Several design parameters for these antennas are considered and analyzed to improve antenna characteristics such as VSWR bandwidth and axial ratio. Initially, the sizes of the aperture and ring radiator are determined on a basis of the cavity model, then shapes of the patch within the aperture and the inner stub of the ring are optimized using Ensemble software. Measurement results show that the aperture-patch antenna has 25% of VSWR bandwidth and 1.2dB of axial ratio at the boresight, and the ring antenna has 6.7% of VSWR bandwidth and 1.6dB of axial ratio at the boresight.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.497-500
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• 2000

There are many researches to increase bandwidth of the microstrip patch antenna for wireless LAN. In spite of broad bandwidth, Bow-Tie microstrip patch antenna, broadband microstrip patch antenna, has disadvantages that are low gain and big size. In this paper, stacked Bow-Tie microstrip patch antenna for wireless LAN is designed in 5.725∼5.825㎓ band. This antenna has characteristics that are broadband bandwidth, high gain and small size compared with microstrip patch antenna. In simulated results, the return loss is -34.2㏈ at 5.78㎓ and bandwidth is 11.345% for VSWR 2：1 and 7.75% for VSWR 1.5：1. In measured results, the return loss is -38.45㏈ at 5.78㎓ and bandwidth is 13% for VSWR 2：1 and 5.6% for VSWR 1.5：1. It has 59.37$^{\circ}$-3㏈ beam width and 6.5㏈ gain.