• 한국전자파학회논문지
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• 제10권2호
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• pp.302-311
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• 1999

본 논문에서는 실내 무선환경에서 최적 편파 다이버시티를 구성하는 방안을 제시하기 위하여 먼저 이론적 해석을 통하여 교차편파식별도(XPD : Cross Polarization Discrimination)를 해석하고 이를 실제 측정 데이터와 비교하였다. 그 결과 아직까지 본 연구실에서 가장 좋은 편파 다이버시티로 확인된 바 있는 원형편파안테나 로 송신하고 수직, 수평편파안테나로 수신하는 경우(CV-CH)의 교차편파식별도(XPD)는 수직편파안테나로 송신하고 수직, 수평편파안테나로 수신하는 경우(VV-VH)와 수평면파안테나로 송신하고 수평편파, 수직편파 안테나로 수신하는 경우(HH-HV)보다 우수함을 확인하였다. 본고에서는 더 좋은 CV -CH 편파다이버시티 구 성을 위해 수신단에서 교차편파식별도(XPD) 값만큼 보상하여 누적확률분포도를 통한 다이버시티 효과를 평 가하였다. 그 결과 보상을 하여 교차편파식별도(XPD) 값을 낮게 한 경우가 보상하지 않은 경우보다 상당한 다이버시티 효과가 있음을 확인하였다. 한편, 송신측의 원형편파 안테나의 축 비를 교정하여 타원편파 안테나 로 구성하고, 수신측에서 수평 및 수직 안테나로 수신하면 신호간의 교차편파식별도(XPD)가 최소화되어 편파다이버시티 효과를 향상시킬 수 있음을 알 수 있었다.

• 한국토양비료학회지
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• 제46권4호
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• pp.237-244
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• 2013

Radar remote sensing is appropriate for monitoring rice because the areas where this crop is cultivated are often cloudy and rainy. Especially, Synthetic Aperture Radar (SAR) can acquire remote sensing information with a high temporal resolution in tropical and subtropical regions due to its all-weather capability. This paper analyzes the relationships between backscattering coefficients of rice measured by RADARSAT-2 SAR and growth parameters during a rice growth period. We examined the temporal variations of backscattering coefficients with full polarization. Backscattering coefficients for all polarizations increased until Day Of Year (DOY 222) and then decreased along with Leaf Area Index (LAI), fresh weight, and Vegetation Water Content (VWC). Vertical transmit and Vertical receive polarization (VV)-polarization backscattering coefficients were higher than Horizontal transmit and Horizontal receive polarization (HH)-polarization backscattering coefficients in early rice growth stage and HH-polarization backscattering coefficients were higher than VV-polarization backscattering coefficients after effective tillering stage (DOY 186). Correlation analysis between backscattering coefficients and rice growth parameters revealed that HH-polarization was highly correlated with LAI, fresh weight, and VWC. Based on the observed relationships between backscattering coefficients and variables of cultivation, prediction equations were developed using the HH-polarization backscattering coefficients.

• Journal of Electrical Engineering and information Science
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• 제3권1호
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• pp.117-125
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• 1998

In this paper, in order to investigate the fading reduction effect of narrowband and broadband signals in an indoor multipath propagation environment, both the received narrowband signal while a vehicle unit in motion and the frequency sweeped broadband signal received by vertical polarized antenna, horizontal polarized antenna and circularly polarized antenna are analyzed. Specifically, in order to evaluate polarization diversity effect, we examined the difference of fading reduction effect between the polarization diversity reception and the space diversity reception. Using the correlation coefficient and correlation graph for the polarization diversity branches, the diversity effect is evaluated. And also, using the cumulative distribution for the received signal strength simulated by diversity reception, the diversity effect is also estimated. From the evaluation results it was found that the polarization diversity which use a circularly polarized antenna at the transmitting end and the vertical and horizontal polarized antenna branches at the receiving end is markedly excellent.

• 한국전자파학회논문지
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• 제22권2호
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• pp.228-235
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• 2011

본 논문에서는 위상 배열 시스템에서 활용 가능한 $4{\times}8$ 이중 편파 기판 집적 도파관(SIW: Substrate Integrated Waveguide) 슬롯 배열 안테나를 제안한다. 제안된 배열 안테나는 수직 편파 안테나와 수평 편파 안테나로 구성 되어 이중 편파가 가능하며, 수직 편파 안테나는 기존의 기판 집적 도파관을 이용하여 가로 슬롯 선형 안테나를 배열하였으며, 수평 편파 안테나는 half mode 기판 집적 도파관(HMSIW: Half Mode Substrate Integrated Waveguide)을 사용하여 세로 슬롯 선형 안테나를 배열하였다.

• 한국토양비료학회지
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• 제47권2호
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• pp.85-91
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• 2014

Ground-based polarimetric scatterometers have been effective tools to monitor the growth of crop with multi-polarization and frequencies and various incident angles. An important advantage of these systems that can be exploited is temporal observation of a specific crop target. Polarimetric backscatter data at L-, C- and X-bands were acquired every 10 minutes. We analyzed the relationships between L-, C- and X-band signatures, biophysical measurements over the whole corn growth period. The Vertical transmit and Vertical receive polarization (VV) backscattering coefficients for all bands were greater than those of the Horizontal transmit and Horizontal receive polarization (HH) until early-July, and then thereafter HH-polarization was greater than VV-polarization or Horizontal transmit and Vertical receive polarization (HV) until the harvesting stage (Day Of Year, DOY 240). The results of correlation analysis between the backscattering coefficients for all bands and corn growth data showed that L-band HH-polarization (L-HH) was the most suited for monitoring the fresh weight ($r=0.95^{***}$), dry weight ($r=0.95^{***}$), leaf area index ($r=0.86^{**}$), and vegetation water content ($r=0.93^{***}$). Retrieval equations were developed for estimating corn growth parameters using L-HH. The results indicated that L-HH could be used for estimating the vegetation biophysical parameters considered here with high accuracy. Those results can be useful in determining frequency and polarization of satellite Synthetic Aperture Radar stem and in designing a future ground-based microwave system for a long-term monitoring of corn.

• Journal of information and communication convergence engineering
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• 제19권3호
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• pp.131-135
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• 2021

The interference between closely placed co-coverage satellites was analyzed. In general, a satellite network may use different orthogonal polarizations and frequencies to increase the throughput of a satellite. However, when orthogonal linear polarization (horizontal polarization and vertical polarization) or orthogonal circular polarization (left-handed circular polarization and right-handed circular polarization) is used, the signal from one polarization sense to another may be coupled, resulting in cross-polarization interference. This signal-coupling arises due to the finite value of the cross-polarization discrimination of the earth station. In this study, field equations were used to analyze the interference between adjacent satellites using co-frequency. The level of interference was compared to that when two adjacent satellites used the same polarization. The simulation results show that the interference mainly depends on the off-axis co-polar pattern and the cross-polar pattern of the earth station antenna.

• 한국전자파학회논문지
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• 제16권4호
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• pp.397-401
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• 2005

본 논문에서는 복잡한 무선통신 환경에서 편파 다이버시티를 사용하기 위하여 편파 변환 기능을 갖는 개구결합 마이크로스트립 안테나를 제안하였다. 제안된 안테나는 다층기관의 배면에 급전을 위한 마이크로스트립 선로를 가졌으며, 그 위의 접지면에는 $\lambda{g}/4$ 간격으로 2개의 슬롯이 위층의 방형 방사 패치의 변과 평행하게 놓여져 있다. 마이크로스트립 급전선로의 종단에 연결한 핀 다이오드를 개방과 단락으로 변환함에 따라 하나의 슬롯이 선택되어 패치에 급전하도록 함으로써 편과를 수평이나 수직으로 변환하는 구조로 하였다. 제작된 안테나의 공진주파수는 수평, 수직편파에서 파자 $2.41\;\cal{GHz},\;2.40\;\cal{GHz}$로 나타났고 편파 분리도는 $19\;\cal{dB},\;23\;\cal{dB}$극 보였으며 $-10\;\cal{dB}$ 반사 손실 대역폭은 각각 $95\;\cal{MHz},\;100\;\cal{MHz}$이었고 이득은 $6\;\cal{dBi}$로 나타났다.

• 한국전자파학회논문지
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• 제24권5호
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• pp.492-501
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• 2013

본 논문에서는 S-밴드에서 하나의 급전 회로로 4개의 편파(수직 편파, 수평 편파, 좌선회 편파, 우선회 편파)를 선택적으로 사용할 수 있는 다중 편파 재구성 마이크로스트립 안테나를 제안하였다. 제안된 안테나는 십자 슬롯과 원형 슬롯을 포함하는 정사각형 형태의 마이크로스트립 패치와 4개의 PIN 다이오드로 구성되어 있으며, 커플링을 통한 급전 방식을 이용한다. 각각의 PIN 다이오드에는 직류 전압을 인가하기 위한 바이어스 단이 있으며, 직류 전압의 인가에 따른 다이오드 ON / OFF 동작으로 편파를 재구성할 수 있다. 제작된 안테나는 수직 편파(3.17~3.21 GHz), 수평 편파(3.16~3.20 GHz), 좌선회 편파(3.08~3.19 GHz), 우선회 편파(3.10~3.20 GHz)에서 VSWR 2:1을 만족하며, 선형 편파에서는 20 dB 이상의 교차 편파 및 5 dBi 이상의 이득 특성을 갖고, 원형편파에서는 50 MHz 이상의 3 dB 축비 특성을 나타낸다.

• Journal of Astronomy and Space Sciences
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• 제41권1호
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• pp.25-33
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• 2024

This paper evaluates the influence of rainfall on propagated signal at different time exceedance percentages of an average year, over the climate zones of the country. Specifically, it demonstrates critical and non critical signal fade or signal outage time exceedance (0.001% to 1%) for Ku, K, and Ka-band systems in an average year. The study was carried out using meteorological data made available by the Nigerian Meteorological Agency (NiMet) over a period of 10 years (2009-2018). The four climate zones in the country were represented by five (5) locations; Maidugiri (warm desert climate), Sokoto (tropical dry climate), Port Harcourt (tropical monsoon climate), Abuja and Enugu (tropical savanna climate). The parameters were simulated into the International Telecommunications Union Recommended (ITU-R) models for rain attenuation over the tropics and results presented using MatLab and Origin Lab. Results of Ku band propagations showed that only locations in the tropical savanna and tropical monsoon climates experienced total signal outage for time percentage exceedance equal to or below 0.01% for both horizontal and vertical polarizations. At K band propagations, the five locations showed to have experienced signal outage at time exceedance equal to and below 0.01%, almost same was recorded for the Ka-band propagation. It was also observed that horizontal and vertical polarization of signal had slightly different rain attenuation values for the studied bands at the five locations, with horizontal polarization having higher values than vertical polarization.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.582-585
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• 2004

Oyster fanning structures in tidal flats are well detected by SAR system. Each frame of these artificial structures is composed of two vertical and one horizontal wooden pole. We investigate characteristics of polarimetric features in the target structures. In this paper, the results of AIRSAR L-band POLSAR data and experiments in laboratory are discussed. The ratio of single bounce to double bounce scattering depends of vertical pole height, direction of horizontal pole to radar look direction, and incidence angle as well as sea surface condition. We have conducted laboratory experiments. According to target scale, Ku-band and targets downsized by scale of 10 are used. The results of the experiments are summarized as: i) total power of the backscattering is more affected by vertical poles than a horizontal pole; ii) and backscattering from a horizontal pole is sensitive to the relative radar look direction to target array. We conclude that water level can be effectively measured by using interferometric phase and backscattering intensity if vertical poles in the water are observed by L-band HH- or VV-polarization. Measurement of tide height can be further improved if double bounced components are separated from fully polarized SAR data.