• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.33-39
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• 2013

In this paper, X/Ku band waveguide diplexers with H-plane T-junction for satellite communication systems is proposed and its characteristics is cinfirmed. Two frequency bands such as X(7.25 ~ 8.4 GHz) and Ku(12.25 ~ 14.5 GHz) can be separated by the proposed waveguide diplexers. A diplexers is normally including low pass filter, high pass filter and junction waveguide. To simplify the structure of the proposed diplexers, the proposed waveguide diplexers is using impedance matching technique on H-plane of the high pass filter without low pass filter. To use vertical and horizontal polarization, the proposed diplexers with orthomode transducer(OMT) characteristics is also designed. Therefore, it is confirmed that the proposed waveguide diplexers can be used as dual-band and dual-polarization diplexers for satellite communication feed systems.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.69-74
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• 2000

The bandwidth of microstrip slot antenna with T-shaped feed line was a wider than one of the conventional feeding structure. When the slot antenna with bi-directional radiator wants to radiate only one direction, the reflector must be set up seperately. But this antenna doesn't need set up reflector. And then we proposed to a new method of a directional slot radiator with a cross-shaped feedline including the reflector using 2-layers dielectric materials. It is calculated waves and electric field distribution in the time domain by using FDTD method. We also are calculated return loss, VSWR, input impedance, and radiation pattern in the frequency domain by Fourier transforming the time domain results, respectively. It was found that the bandwidth of this antenna changes as length($\I_s$) and width($\W_s$) of slot, length of the horizontal feedline($\I_d$), length of the vertical feedline($\I_u$) and offset sensitively. After optimizing the parameters of design, the maximum bandwidth was measured as 1,850MHz at the center frequency 2.5 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.830-838
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• 2003

In this paper, TX/RX dual operation microstrip single antenna for satellite communication is designed, analyzed, fabricated and measured. TX/RX frequency ranges are 14.0∼l4.5 GHz, 11.7∼12.75 GHz in respectively and vertical and horizontal polarizations are used for TX and RX. This antenna uses microstrip direct feeding for RX and aperture coupled strip-line feeding for TX and accommodates stacked elements for a high directivity and wide impedance bandwidth. In an analysis of single element, FDTD and MOM was compared and FDTD analysis was more accurate because of the consideration of finite structure and imperfect two ground planes. The proposed structure facilitates generally to an extension of two dimensional array and lower an unwanted radiation by strip-line feed in TX. TX/RX 8${\times}$4 array has a return loss below -10 dB, -14 dB in TX, RX respectively and a gain ranging from 19.1∼20.7 dB in TX, 21.2∼21.8 dB in RX which has a radiation efficiency of 43∼5l %, 52∼57 %.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.509-516
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• 1999

In this paper, it is designed a microstrip U-slotted patch antenna with double resonances to enhance the bandwidth. In the design of an U-slotted patch antenna, there are considered the input impedance, the width of patch, the total length of the slot, the height of foam, the position of the probe and the radius of feed pin. The broadband behavior of antenna can be obtained by adjusting the length and width of the slot. The radiation from the antenna is linear polarized with the E-paine parallel to the vertical slots and the H plane parallel to horizontal slot. The radiation pattern, impedance locus, and VSWR of the antenna are calculated using "ENSEMBLE" software, and compared with the experimental results. Experimental results show that the bandwidth for VSWR $\le$ 2:1 is about 28.6%, a directivity 14.18dBi at 6.040GHz. 6.040GHz.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.117-128
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• 2018

In this paper, compact linear dual polarized series-fed $1{\times}2$ linear and $2{\times}2$ planar arrays antennas for airborne SAR applications are proposed. The proposed antenna design consists of a square radiating patch that is placed on top of the substrate, a quarter wave transformer and $50-{\Omega}$ matched transformer. Matching between a radiating patch and the $50-{\Omega}$ microstrip line is accomplished through a direct coupled-feed technique with the help of an impedance inverter (${\lambda}/4$ impedance transformer) placed at both horizontal and vertical planes, in the case of the $2{\times}2$ planar array. The overall size for the prototype-1 and prototype-2 fabricated antennas are $1.9305{\times}0.9652{\times}0.05106{{\lambda}_0}^3$ and $1.9305{\times}1.9305{\times}0.05106{{\lambda}_0}^3$, respectively. The fabricated structure has been tested, and the experimental results are similar to the simulated ones. The CST MWS simulated and vector network analyzer measured reflection coefficient ($S_{11}$) results were compared, and they indicate that the proposed antenna prototype-1 yields the impedance bandwidth >140 MHz (9.56-9.72 GHz) defined by $S_{11}$<-10 dB with 1.43%, and $S_{21}$<-25 dB in the case of prototype-2 (9.58-9.74 GHz, $S_{11}$< -10 dB) >140 MHz for all the individual ports. The surface currents and the E- and H-field distributions were studied for a better understanding of the polarization mechanism. The measured results of the proposed dual polarized antenna were in accordance with the simulated analysis and showed good performance of the S-parameters and radiation patterns (co-pol and cross-pol), gain, efficiency, front-to-back ratio, half-power beam width) at the resonant frequency. With these features and its compact size, the proposed antenna will be suitable for X-band airborne synthetic aperture radar applications.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.1
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• pp.11-21
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• 2020

This paper deals with the impact of a GNSS (Global Navigation Satellite System) antenna radome on the PCV (Phase Center Variations) and the estimated kinematic coordinates. For the Trimble and Leica antennas, specially set up CORS (Continuously Operation Reference Stations) in Korea, the PCC (Phase Center Corrections) were calculated and compared for NONE, SCIS, SCIT, and TZGD radome from the PCV model published by the IGS (International GNSS Services). The results revealed that the PCC differences compared to the NONE were limited to about 1mm in the horizontal component while those of the vertical direction ranged from a few millimeters to a maximum of 7mm. Among the radomes of which PCV were compared, the SCIT had the most significant influence on the vertical component, and its GPS (Global Positioning System) L2 and L2 PCC (Phase Center Corrections) had opposite direction. As a result of comparing the kinematic coordinates estimated by the baseline processing of 7 CORSs with an application of the PCV models of the various radomes, the SCIS which was actually installed at CORS in Korea showed 3.4mm bias, the most substantial impact on the ellipsoidal height estimation whereas the SCIT model resulted in relatively small biases.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.3
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• pp.207-215
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• 2022

This research has been focused on accessing precision and accuracy of UAV (Unmanned Aerial Vehicle)-derived 3-D surveying coordinates. To this end, a highly precise and accurate testing control network had been established by GNSS (Global Navigation Satellite Systems) campaign and its network adjustment. The coordinates of the ground control points and the check points were estimated within 1cm accuracy for 95% of the confidence level. FC330 camera mounted on DJI Phantom 4 repeatedly took aerial photos of an experimental area seven times, and then processed them by two widely used software packages. To evaluate the precision and accuracy of the aerial surveys, 3-D coordinates of the ten check points which automatically extracted by software were compared with GNSS solutions. For the 95% confidence level, the standard deviation of two software's result is within 1cm, 2cm, and 4cm for the north-south, east-west, and height direction, and RMSE (Root Mean Square Error) is within 9cm and 8cm for the horizontal, vertical component, respectively. The interest is that the standard deviation is much smaller than RMSE. The F-ratio test was performed to confirm the statistical difference between the two software processing results. For the standard deviation and RMSE of most positional components, exception of RMSE of the height, the null hypothesis of the one-tailed tests was rejected. It indicates that the result of UAV photogrammetry can be different statistically based on the processing software.

• Journal of Korean Society of Forest Science
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• v.78 no.2
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• pp.177-188
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• 1989

The habitat typing method of classification based on community has been developed on many forested areas in the ROCKY MOUNTAINS of WESTERN NORTH AMERICA, and is being used in providing an objective principle of guide for classification of forest sites, land classification, vertical distribution and multipurpose management of forest. I actually made a trial of forest habitat type classification - The methodology can be segmented into a number of tasks including reconnaissance, selection of stands to be sampled, location of plots, data gathering, preliminary and computer analysis, preparation of key- and map of habitat type and description for each habitat type in a view of forest management - on UNIVERSITY OF MONTANA FORESTS in order to examine whether its application is fit or not in korean forest circumstances : these are composed mainly of artificial forest and forest in the early stage of succession. The main results obtained from this study were summarized as follows 1. A hierarchical classification-Climax, Habitat type and Phases-of forest sites was developed using the habitat typing method of classification. 2. A diagnostic key is provided for field identification of the types based upon presence and number of indicator species, and forest managers could prepare a map of habitat type and classify forest habirat types by reference to it. 3. The classified habitat types were considered to be effective on providing an objective principle of guide for multipurpose management of forest including potential productivity for timber, feed productivity of forage and wildlife, selection of the right species in the right sites, application of method of treatment and so forth. 4. Forest habitat type classifications based upon extrapolation which used relict species and associated stands is considered to be suitable for korean forest circumstances and objective in studying potential vegetation, vertical and horizontal distribution of forest.