• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.476-482
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• 2006

In this paper, a multimode feed horn antenna is suggested for a high power microwave(HPM) antenna system. The proposed HPM feed horn antenna which is connected with a mode converter is located between source and reflector antenna. A multimode feed horn antenna which has reduced -25 dB beamwidth is designed and fabricated for miniaturization of reflector antenna because -25 dB beamwidth which is determined by considering spillover of feed horn antenna decides a size of reflector in case of HPM. As a result, feed system which uses the multimode feed horn antenna has high gain about 27 dBi and return loss is less than -22 dB at 10 GHz. The measured -25 dB beamwidths of the radiation pattern at vertical, horizontal-plane equal to $20.24^{\circ},\;28.92^{\circ}$ which is less than about $10^{\circ}$ beamwidth of conventional feed system. Thus the suggested feed hem antenna is suitable to feed horn for miniaturization of HPM antenna system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.1-7
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• 2016

In this paper, the design methodology of a corrugated conical horn antenna is proposed to be obtain wide-band properties over the full range of frequencies in the Ku-band. In order to improve the properties of the corrugated conical horn antenna, such as its gain, VSWR, co-polarization to cross-polarization ratio and wide-bandwidth, two types of mode matching converters are implemented within it. One is located at the end of the circular waveguide, while the other is positioned in front of the horn-flare section. The properties of the antenna are analyzed and compared according to the position of the proposed converters through simulations. In the comparison of the antenna performance in the case where the VSWR, co-polarization to cross-polarization ratio and antenna gain over the Ku band of 12-18 GHz are less than 2, greater than 30dB and 20dB respectively, the former antenna exhibits greater stability and a wider frequency band than the latter from the viewpoint of transmitting and receiving signals simultaneously. Therefore, considering the gain, VSWR, radiation pattern and bandwidth, the horn antenna structure in which the mode matching converter is implemented inside the circular waveguide has better performance than the other.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.970-976
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• 2002

In this paper, the slump flow of the concrete, suspension, pH, corrosion effect, bleeding and the characteristics of coompressive strength were analyzed using antiwashout underwater admixture and antiwashout underwater agent+corrosion inhibitor mixed admixtures(1type). The results showed that there were no rare difference in physical properties but in the results of rapid corrosion tests there were lots of corrosion inhibitor ratio differences between concrete using only antiwashout underwater admixture and the corrosion inhibitor mixed(1type). In the case of only antiwashout underwater admixture 5.4%, the case corrosion inhibitor mixed(1type) 0.07%, the Antiseawater of the concrete which uses the Corrosion Inibitor Mixed(1type) appeared highly.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.5
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• pp.389-392
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• 2018

Herein, a horn antenna that has the maximum back lobe reduction characteristic using a corrugated structure at 1.57 GHz for a high-power microwave system is proposed. The back-lobe characteristics of the proposed antenna was optimized using simulation as the number of corrugated structures increase, and the three-staged corrugated structure was designed. Consequently, the front-to-back ratio(FBR) of the fabricated antenna is 47.2 dB, which is improved by 23.7 dB based on that of the basic horn antenna, i.e., 23.47 dB.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.118-126
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• 2011

The characteristics of the responses obtained in thermosonic tests are investigated in this study to improve the performance of a thermosonic test system. Thermosonic tests are conducted with an acoustic horn with high power capability to investigate the characteristics of the vibration produced in turbine blades with complex geometry. The influences of the excitation signal that is input to the horn and the coupling methods between a clamp and the acoustic horn on the characteristics of the vibration excited in a component are presented. As a result, an excitation method with a fast narrow band chirp test (sweep test) and a stud coupling is proposed as an excitation method for thermosonic testing. This method can be applied to different types of turbine blades and also to other components.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.12
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• pp.1193-1200
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• 2016

In this paper, we developed a system for measuring a passive intermodulation distortion signal of the mobile communication RF module having a wide band characteristic. The Broadband was designed to represent the characteristics of the receiver to meet the low noise characteristics and wideband characteristics in the RF receiver were to represent a wide dynamic range(high dynamic range)from the RF receiving end. PIMD designed passive intermodulation distortion signal measured by applying the FPGA / DSP in the system was measured to record the program on the PC. Variable up to 650MHz-2700MHz showed up to-138dBc measured PIMD3.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.109-113
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• 2015

This paper presents the study results on a dual band feed horn for the focused reflector. A coaxial waveguide structure is attractive to avoid blockage from the feeder. The inner conductor as a hollow waveguide is designed to excite TE11 of a circular waveguide for high frequency. For low frequency, the design of the outer coaxial waveguide that propagates coaxial TE11 and prevents fundamental TEM is presented. The horn size for generation of these modes results in the degradation of performance. The return loss is improved by a capacitive iris and an inductive iris The enhanced pattern symmetry by dual mode is presented. The horn design in this paper are verified through the test.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.2
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• pp.20-28
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• 1994

Theoretical radiation patterns for the corrugated horn antenna are analyzed by vector integral method and quasi-optics. The formular of the radiated fields for the corrugated horn antenna can be obtained by the potentials derived the equivalent current sources from hybrid fields at horn aperture and also calculated by the expanded mode set of Gaussian - Laguerre based on the quasi - optics. From comparison of the radiation patterns between two methods for a corrugated horn antenna designed on 85-115 GHz frequency range, the results are coincided well at center frequency but have some errors at each side frequencies 85 and 115 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.492-498
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• 2000

When multi-carriers are applied to the high power amplifier(HPA) having nonlinear characteristics, the HPA output has unwanted IMD signals. The IMD signal is noise in the HPA. The magnitude and phase of the main and IMD signal of HPA output are changed as the input signal power is changed. If we know exactly the magnitude and phase characteristics of the main and IMD signal, we can design a more adequate linearizer and understand the characteristics of transistor. In this paper the magnitude and phase of the main and IMD signal of HPA output are measured and analyzed for variation of the input power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.703-705
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• 2016

In this paper, we developed a wideband PIMD system to measure passive intermodulation distortion signals of mobile communication RF passive module. To represent wideband characteristic, we designed a receiver that meets low-noise and wideband characteristics in RF receiver. It allows high dynamic range in the RF receiver front end. In designed passive intermodulation distortion measurement system, we programed to display a PIMD signal with FPGA/DSP at PC. Implemented PIMD system was variable from 650 MHz to 2700 MHz and show up to -138 dB minimum detectable $3^{rd}$ passive inetrmodulation distortion signal.