전파모델을 이용한 도심지 전파경로 손실 예측

짱차오 호남대학교 대학원 2012 국내석사

이동통신은 주변 환경의 지형에 영향을 많이 받아서 전파 전송에 대한 예측은 이동통신 시스템의 설계 및 서비스 실시에 아주 중요한부분이다. 전파의 전파예측은 무선네트워크 설계나 실제 네트워크 효과에 결정적인 영향을 미친다.

도전성 섬유를 이용한 전파흡수체에 관한 연구

오경진 한국해양대학교 대학원 2006 국내석사

In this thesis, EM wave absorbers were fabricated with MnZn, NiZn, Ba ferrites, and Sendust on the basis of very thin conductive fibers. The purpose of this research is to develop a complex EM wave absorber with superior EM wave absorption based on conductive fibers. A conductive fiber which has shield property of 20~40 dB in GHz was used in this work. The absorption ability of EM wave absorber can be increased by using the conductive fibers, because some absorbtion and return losses can be occurred by the conductive fibers. Moreover, the conductive fibers are of light weight, thin thickness, and can be used as binders to fabricate complex EM wave absorbers, therefore it is possible to apply them to the fabrication of EM wave absorber without influencing their weight and volume. Complex EM wave absorbers were made by pasting a sheet of fiber on the backside of existing absorber using epoxy paint which is flexible and not fragile. In this thesis, two types of fibers, (one is gold-plated with about 0.1Ω/ ㎠ surface resistance, and the other is alumina-plated with 60 Ω/ ㎠ surface resistance), are used, and some EM wave-absorbing materials with high absorption ability, such as MnZn, NiZne, Ba ferrite, and Sendust are used. As the experimental results, the gold-plated fibers couldn't increase absorption ability but could be used as EM wave shielding materials because of their high shielding efficiency, light weight, and thin thickness (about 0.09 mm). Comparing the EM wave absorbers composed of the alumina-plated sheet with ones fabricated without the alumina-plated sheet, the former improve the absorption abilities due to the reflection and absorption losses resulted from the alumina-plated sheet itself. Shielding efficiency of alumina-plated sheet is not better than the gold-plated sheet. However, it can be used as EM wave absorbers materials because of its average shielding efficiency of 20 dB to the EM wave absorbers in GHz band, and its thickness is 0.25 mm, weight is light as well as the gold-plated sheet. Fabricated MnZn ferrite, Ba ferrite, NiZn ferrite, and Sendust EM wave absorbers are useful as a EM wave absorber for S-Band, Ku-Band and C-Bnad, respectively. This thesis shows that EM wave absorber fabricated with conductive fibers can be a candidate of EM wave absorber with superior EM wave absorption ability for GHz band and do not allow permeation of unwanted EM waves.

초광대역 전파흡수체의 설계 및 제작에 관한 연구

손준영 한국해양대학교 대학원 2005 국내박사

With the progress of electronics industry and radio communicaton technology, mankind might enjoy its abundant life. On the other hand, serious social problems such as electromagnetic interference (EMI), have arisen due to the increased use of electromagnetic (EM) waves. Therefore, International organizations such as CISPR, FCC, ANSI, etc., have provided the standards for the EM wave environment and for the countermeasure of the electromagnetic compatibility (EMC). EM wave absorbers are used for constructing an anechoic chamber in order to test and measure EMI and electromagnetic susceptibility (EMS). It has been recognized that the absorption ability of the EM wave absorber has more than 20 ㏈, and the absorption frequency band is required through 30 ㎒ to 1,000 ㎒ for satsfying the international standards about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR has acccepted the extended frequency band from 1 ㎓ to 18 ㎓ additionally in the bandwidth of EMI measurement. In this dissertation, an EM wave absorber with super wide-band frequency characteristics was proposed in order to satisfy the above requirements and designed using the EMCM. Furthermore, a new simulation and analysis methods were adopted by the FDTD method. The bandwith of the proposed EM wave absorber was confirmed by simulation and experiments, which has the bandwidth from 30 ㎒ to above 6 ㎓. In the experiments, tapered rectangular coaxial line was used. In addition, to improve absorption ability of Ferrite EM wave absorber, the ferrite EM wave absorber on which pyramidal EM wave absorber is attached. As a result, the frequency band from 30 ㎒ to 18 ㎓ obtained under the tolerance limits of more than 20 ㏈ absorption.

태양위치 전파센서의 측정 정밀도 향상을 위한 상관형 시스템에 관한 연구

조홍열 湖南大學校 2011 국내석사

본 논문은 본 연구실에 의해 기존에 개발된 단일 안테나형 태양 위치 측정 전파센서의 문제점과 위치 측정 정밀도 향상을 위한 방안으로 상관형 시스템을 제안한다. 제안한 상관형 태양 위치 측정 전파센서의 원리 및 시스템 개발 내용과 모의 실험에 의한 유효성 입증에 대해 기술하였다. 먼저 태양 위치 측정 전파센서의 정밀도 향상에 있어서, 기존의 단일 안테나형 태양 위치 측정 센서와 비교하면 상관형 전파센서는 주변의 환경요인에 영향을 최소화하며, 간섭패턴을 이용하여 태양위치의 측정 정밀도를 향상 시킬 수 있다. 태양위치 측정을 위해 마이크로파 대역에서의 태양 복사 특성을 분석하였으며, 연구실에서 제작된 C -Band 수신기를 기반으로 IF 주파수 대역의 Down Convertor 수신기가 개발되었다. 수신 중심 주파수를 300MHz에 20MHz 대역폭을 가진 수신기를 개발하였고, 최대 수신감도는 -20˚C ~ 50˚C의 수신기 동작온도범위에서 대역폭을 고려하여 △T = 0.41K 이내로 계산되어진다. 실용화가 가능한 최적의 상관형 시스템을 위해 Matlab Tool 시뮬레이션 결과 최적의 안테나 배열을 도출하였다. 상관형 시스템의 특성상 두 개의 동일한 특성을 가진 수신기가 필요함으로 각 채널 수신 이득의 오차를 0.5dB 이하로 개발하였으며, 상관처리부의 결과를 획득하기 위해 수신시간을 동기화 시켜, 디지털 오실로스코프와 Matlab Tool을 이용하여 상관형 시스템의 출력 특성 결과 얻어냈다. 최적 안테나 배열 값으로 얻어진 상관형 시스템을 구축한 후 필드 테스트를 통하여, 기존 수신기보다 최대 10배의 빔 압축의 효과와 태양위치 측정 후의 정밀도를 3.76배까지 향상 가능함을 확인하였다. 이로써 상관형 시스템의 태양위치 측정 정밀도 향상 가능성을 제시하였으며 실용화에 기여할 것으로 기대된다. The present thesis in compliance with the laboratory where it sees proposes a higher officer style system with the plan for the problem point and a location measurement precision improvement of the single antenna style solar location measurement electronic sensor which is developed in existing. It described in about the effectiveness proof in compliance with the principle and a system development contents and a conference experiment of the higher officer style solar location measurement electronic sensor which proposes. There is first to precision improvement of the solar location measurement electronic sensor and when with the single antenna style solar location measurement sensor of existing it compares, the higher officer style electronic sensor will minimize an effect in the environmental factor of circumference, it will use improvement possibility it will make the measurement precision of solar location and an interference pattern. It respected a solar location measurement to analyze the solar radiation quality from microwave substitute actor, Down Converter receivers of IF frequency ranges were developed the C - Band receivers which are produced from the laboratory in base. Reception center frequency to develop the receiver which has 20MHz bandwidth in 300MHz, the maximum receiving sensitivity to consider a bandwidth from -20˚C ~ 50˚C receiver operational temperature range and be calculated within △T = 0.41K. It respects the higher officer style system of the optimum whose putting to practical use is possible antenna array Matlab Tool simulation resultant optima escape. Quality as a matter of two of higher officer style system in order a higher officer control bringing up for discussion result the receiver which has the quality which is identical is below 0.5dB to develop the error of necessary with each Channel reception profit, to acquire it synchronizes a time of receipt. the digital oscilloscope and to use Matlab Tool output quality result of higher officer style system it gets, to make After constructing the higher officer style system which it comes to get at optimum antenna array price field test it led, the effect and a solar location measurement kind precision of the compression the maximum 10 time being emptier the existing receiver than until 3.76 times improvement it is possible it confirmed. From this cause it presents the solar location measurement precision improvement possibility of higher officer style system and it will contribute in putting to practical use with the fact that.

이동 통신 대역 전파 모델 예측 방법론에 관한 연구

박경태 한국해양대학교 대학원 2011 국내박사

In this doctorial dissertation, the researched topic is the partial propagation prediction methods. The prediction methods of propagation model in the cellular band are introduced in order to improve the inaccuracy of the macroscopic conventional propagation model. By use of the researched methods, a better prediction model can be extracted from the conventional propagation models. The main purpose of the new methods is to solve problems of the conventional propagation models and to improve the efficiency of the propagation model. There are many area-to-area prediction models in the conventional methods. Because of the simplicity of two important parameters in the area-to-area propagation model which are the 1-Km path loss value and the path loss slope, the application area has been restricted. Another propagation model is the point-to-point propagation model. In this model, it was considered the propagation environment such as the lay of the land, the positions and heights of buildings, the density of crowded cars, and the density of trees. But, the information for the propagation environment is so complicated that the new partial propagation methods are introduced. The first researched topic is the partial propagation method by using the conventional and theoretical propagation models. The theoretical models are quite well formulated by the physical theory. The averages and standard deviations for the difference values of the field-measured values and the conventional model values are calculated. A best model for the measured value is chosed by the lowest calculated standard deviation. To reduce the error between the measured value and the model value, the distance interval between the transmitter and receiver is divided to small one such as 8, 4, 2, 1, 0.5, 0.25 Km. For each 8 Km, the averages and standard deviations for the path loss were calculated, and then the best models are chosen for the 8 Km intervals. Likewise, by reducing the interval to 0.25 Km, the statistical information for the mean and standard deviation can be obtained. Also, the best model for each 0.25 Km interval can be obtained, too. After the above methods are applied, the standard deviation is considerably reduced by the newly suggested partial propagation models. The second researched topic is the partial propagation method by the conventional real-measured major-city propagation models. The real-measured major-city models are so widely known models that the models were used as sample models by the partial propagation models. The application procedures are similar to the previous one. The interval is reduced from the entire distance to 8 Km and finally 0.25 Km, and then the compared averages and standard deviations are obtained. As a result, the differences are also considerably reduced. The researched partial propagation methods which are compared to the theoretical and real-measured major-city models show that the means and standard deviations are so considerably improved that the differences between the measurement values and the new models were decreased. The representative propagation model for each partial distance was decided according to the path loss slope of the conventional propagation model. This researched methods of the partial propagation prediction model enable us to decide the best describing propagation models for the measured area with advantages of quitely reduced standard deviations. For the generalized partial propagation method, the interval is divided to each 8 Km, 4 Km, 2 Km, 1 Km, 0.5 Km, or 0.25 Km. At each interval, the path loss parameters are extracted which are 1-Km path loss, path loss slope, and path loss environment constant. By use of the parameters, the path loss model is obtained as follows : . Applying the partial path loss models and each three parameters to the entire distance, the path loss models for the un-measured area can be easily obtained with the minimum standard deviations. 본 논문에서는 거시적인 경로 손실 모델이 지니고 있는 문제점을 개선하기 위하여 구간 분석법을 적용한 전파 모델 예측 방법을 제시하였다. 제안한 구간 분석법을 이용한 전파 모델 예측 방법은 기존의 이론 및 실측 전파 모델을 구간별로 적용하는 방법으로, 보다 정확한 경로 손실 모델을 설정하는 연구이다. 제안 방법을 통하여 영역간 전파 모델에서는 구하기 어려운 문제점을 보완하고, 구간 분석 모델과 측정치의 표준 편차를 줄이기 위한 연구를 진행하였다. 측정 구간에 대한 전파 모델 파라미터가 근거리 지점에서의 경로 손실과 경로 손실 경사도라는 두 가지 파라미터로 정의되는 영역간 전파 모델은 실제 경로 손실 현상과는 오차가 커서 적용하기 어렵다. 반면에, 영역간 전파 모델을 기본으로 하고 지형 정보, 빌딩 등 장애물 위치 및 크기, 나무 밀도 등의 전파 환경을 고려한 지점간 전파 모델은 정확한 결과를 얻을 수 있으나, 전파 환경 변수를 반영하기 곤란하다. 따라서, 본 논문에서는 영역 간 전파 모델의 부정확성을 보완하고, 지점 간 전파 모델의 전파 환경 변수 적용을 줄이는 구간 분석법을 제시하였다. 첫 번째 제안한 방법은 기존의 이론 전파 모델을 이용한 구간별 전파 모델 예측 방법론이다. 이 방법에서 사용한 기존의 이론 전파 모델은 물리적인 이론으로 정립되어 널리 이용되기 때문에, 본 논문에서 제안한 구간별 분석법에 적용 하였다. 측정치와 기존 이론 모델들과의 차이에 대한 평균과 표준 편차를 구한 다음, 차이 평균만큼 보정한 기존 이론 모델 중에서 최저의 표준 편차를 갖는 모델을 측정 지역에 대한 최적의 모델로 설정한다. 전 구간에서 하나의 식으로 설정된 모델은 오차가 많기 때문에 구간을 8 Km로 나누어 측정값과 기존 이론 모델들의 차이에 대한 평균과 표준 편차를 구하여, 해당 구간에서 가장 작은 표준 편차를 나타내는 모델을 각 구간에 대한 대표 모델로 선택하였다. 구간 간격을 4 Km, 2 Km, 1 Km, 0.5 Km, 0.25 Km로 줄여가며 측정값과 기존 이론 모델들과의 차이에 대한 평균과 표준 편차를 구하여 해당 구간에 대한 대표 경로 손실 모델을 선택하는 방법을 사용하였다. 전 구간에서 8 Km, 4 Km, 2 Km, 1 Km, 0.5 Km, 0.25 Km로 구간 간격을 줄이면서 측정된 경로 손실과 기존 이론 모델과의 평균과 표준 편차를 구하여 비교해 본 결과, 제안한 방법을 적용하면 측정치와의 표준 편차가 6.17 ~ 5.21 dB로 줄어 듦을 알 수 있었다. 두 번째 제안한 방법은 기존의 실측된 도시 전파 모델을 이용한 구간별 전파 모델 예측 방법론이다. 이 방법에서 사용한 기존의 실측 모델은 세계의 대도시 몇 군데에서 측정된 모델로 비교용으로 널리 이용되기 때문에, 본 논문에서 제안한 구간 분석법에 적용 하였다. 이 방법 또한 앞의 기존의 이론 전파 모델 방법과 동일하게, 전 구간에서 8 Km, 4 Km, 2 Km, 1 Km, 0.5 Km, 0.25 Km로 간격을 줄이면서 측정치와 기존 실측된 도시 모델과의 평균과 표준 편차를 구하여 최저의 표준 편차를 나타내는 모델을 해당 구간에 대한 대표 모델로 설정하였다. 그 결과, 첫 번째 방법처럼 측정치와의 표준 편차가 6.12 ~ 5.21 dB의 분포를 보이는 구간별 대표 모델을 설정할 수 있었다. 위와 같이, 필드 측정을 통한 실험 결과를 기존의 이론 및 실측 모델들과 비교하여 구간 분석법을 적용하여 본 결과, 전체 구간에서 0.25 Km까지 구간 간격을 줄이면서 구한 구간별 대표 모델과 측정치의 표준 편차가 두 경우 모두 5.2 dB까지 점점 줄어들었다. 이 방법을 적용하게 되면, 지점간 전파 모델에서의 전파 환경을 별도로 조사하지 않고도 측정치와의 표준 편차가 5.2 dB까지 줄어든 전파 모델을 설정할 수 있다. 본 논문에서 제안한 구간 분석법을 러시아의 5개 도시 지역에서 측정한 데이터에 적용하게 되면, 측정치와의 표준 편차가 1.5 dB 개선된 구간별 전파 모델의 설정이 가능한 결과를 얻었다. 다음으로, 구간 분석 방법론을 일반화하기 위하여, 구간 간격을 8 Km, 4 Km, 2 Km, 1 Km, 0.5 Km, 0.25 Km로 나누고, 각 구간별로 구간 분석 방법론의 세 가지 파라미터인, 1-Km 지점에서의 경로 손실 , 경로 손실 경사 , 경로 손실 환경 상수 에 대한 값을 구하여 표와 그림으로 나타낼 수 있었으며, 세 가지 파라미터 값들을 구간별로 구하게 되면, 구간 분석법을 적용한 의 전파 모델을 설정할 수 있게 된다. 구간 분석 방법론을 세부 구간들을 합친 전 구간에 대하여 적용하게 되면, 미 측정 지역에서도 최소의 표준 편차를 가지는 경로 손실 모델을 설정할 수 있어서 상당히 유용한 도구임을 확인하였다.

센더스트를 이용한 적층형 전파흡수체의 개발

류재민 한국해양대학교 대학원 2007 국내석사

The remarkable advance of modern electronics and communication technology has made high frequency conversion, miniaturization, digitalization. However, EM (Electromagnetic) wave environments have become more complicate and difficult to control. Therefore, international organizations such as the ANSI (American National Standards Institute), FCC (Federal Communications Commission), and CISPR (the Committee International Special des Perturbations Radioelectrique), etc. have provided international or local standards for the EM wave environments and for the EMC (Electromagnetic Compatibility). EM wave absorbers are used to protect electronic devices, such as personal communications and wireless LAN systems from unwanted EM wave radiations. In order to develop a more advanced EM wave absorbers, it is important to develop new materials for EM wave absorbers instead of soft and hard magnetic materials, such as Mn-Zn, Ni-Zn, Ba, and Sr ferrites which have been used conventionally. In this thesis, the experiments for two kinds of materials. First, Multi-layer EM wave absorbers were studied using Sendust. As a result, the bandwidth of the Multi-layer EM wave absorbers with the thickness of 4 mm using Sendust was obtained more than 10 dB in S-Band. Secondly, the mixing effects of Sendust and on Multi-layer EM wave absorbers were studied, where it was confirmed that the bandwidth of the multi-layer EM wave absorbers inter-mixing with the thickness of 3 mm has broadened compared with non-mixed Multi-layer Sendust EM wave absorbers in S-Band.

V/UHF 대역의 효율적인 스펙트럼 관리를 위한 차세대 전파감시시스템

임현석 충북대학교 2009 국내석사

With rapid development of communication industry, the kinds of communication service vary. According to the increasing use of radio waves, the intelligent and effective radio monitoring system needs to be developed, which is replaced for previous radio monitoring system. Next-Generation radio monitoring system based on ITU-R, Rule of wireless facilities, and Radio Waves Act is used, and which can accurately and effectively function as effective radio monitoring system through spectrum analysis of channel power, frequency deviation, offset, and an occupied frequency bandwidth(99% or x-dB), about the analog and digital signal in On-Air of V/UHF band. Main function of the system has an radio quality measurement, unwanted electromagnetic signals (spurious, harmonic) measurement, high-speed spectrum measurement, frequency usage efficiency investigation, illegal radio exploration, working monitoring, In this paper, we proposes radio quality measurement, high-speed spectrum measurement of Intelligent radio monitoring system.

ETC용 전파흡수체의 개발에 관한 연구

송영만 한국해양대학교 대학원 2008 국내석사

According to the increase of occupation density of microwave frequency band in use, electromagnetic environments become congested extensively. It often cause TV ghost, radar false echoes by wave reflection from adjacent constructions. Especially, in the area where strong reflectors, such as high building, steel tower, iron bridge, etc., exist around radio wave facilities, the performance of such apparatus often deteriorates due to multipath interference between direct wave and those reflected from these constrictions. Thus, to Countermeasure the electromagnetic wave interference, the radiated electromagnetic fields of digital electronic products must be measured and must not exceed the specified levels. In addition, the increase of new devices Electromagnetic Interference (EMI) or Electromagnetic Susceptibility (EMS) problems. Therefore, the international or local regulations suggest certain standards for EMI / EMS. These problems can be eliminated by using EM wave absorbers. It is important to develop absorbing material for preventing EMI. MnZn-ferrite or Carbon is useful as a microwave absorbing material because their electric and magnetic loss contribute to the microwave absorption efficiently. This thesis deal with basic research for development of EM wave absorbers in sheet type for Electronic Toll Collection (ETC), By controlling the MnZn-ferrite ratio, the Carbon ratio, the thickness, the kind of binders, the milling time, EM wave absorbers were prepared and examined. Matching frequency shifts toward higher with decreasing thickness of the absorber, and absorption ability controlled by adjusting MnZn-ferrite and Carbon amount. MnZn-ferrite and Carbon composite microwave absorbers mixed with CPE were prepared at 70℃ in temperature. The fabricated EM wave absorbers show a reflection coefficient - 23 dB at 5.8 GHz in thickness of 3.3 mm by transmission line method. In case incident wave angle was 15°, the EM wave absorber was observed -17 dB at 5.8 GHZ with the thickness of 3.38±0.05 mm, in case incident wave angle was 30°, the EM wave absorber was observed -14 dB at 5.8 GHZ with the thickness of 3.38±0.05 mm, in case incident wave angle was 45°, the EM wave absorber was observed -12 dB at 5.8 GHZ with the thickness of 3.38±0.05 mm by free space method.

자성 손실재료를 이용한 Hi-pass용 전파흡수체의 개발

유건석 한국해양대학교 대학원 2010 국내석사

In this paper, we analyzed and evaluated noise suppression charateristic of EM wave absorber. First, we fabricated several absorber samples in different ratios of Sendust and Amorphous with CPE (Cholorinated Ploy-ethylene) as binder. Secondly, complex relative permittivity and Complex relative permeability was calculated by the measured data. And absorption abilities were simulated according to different thickness of the EM wave absorbers using complex relative permittivity and permeability. The EM wave absorber was fabricated based on simulated data. Simulated and measured value agree well. As a result,, the developed EM wave absorber has a thickness of 2.6 mm and absorption ability over 40 dB at 5.8 GHz.

항만물류 RFID 시스템용 전파흡수체 개발에 관한 연구

최동수 한국해양대학교 대학원 2011 국내석사

With the rapid advancements in electronics industry and radio communication technology, our life has become more abundant than ever before. On the other hand, serious social problems such as electromagnetic interference (EMI) and electromagnetic susceptibility (EMS) have arisen due to the increased use of electromagnetic waves. Therefore, countermeasure against electromagnetic waves obstacle is embossed to be important subject. International organizations such as CISPR, FCC, and ANSI have provided the standards for the EM wave environments and for countermeasure of the electromagnetic compatibility (EMC). Especially, UHF(433 MHz and 860 MHz ~ 960 MHz) band RFID system is widely accepted by industries such as port logistics, circulation, and mobile RFID field advantage of long communication range, high speed transmission of data. Particulary, port logistics RFID systems have several EMC problem such as decrease of communication range and errors by mutiple reflection. Port logistics RFID systems which have hundreds of antennas are positioned in small area, cause the interferences between readers and tags. Thus, to avoid severe communication interruption between RFID systems, we must study carefully. To avoid the communication interruption, EM wave absorber is applicable among readers. Besides, communication range of RFID system is reduced when RFID Tag approached metal plate. In this case, the EM wave absorber can increase the communication range of RFID system when it inserts between tag and metal plate. In this study, the EM wave absorbers are designed and fabricated for preventing reader to reader interference by dense mode and the reduction of the communication range when RFID Tag approached metal plate. The EM wave absorber samples are fabricated with difference composition ratios of Amorphous metal powder and CPE, the S-parameters of samples are measured. Absorption abilities are simulated by substituting different thicknesses of the EM wave absorbers, and the EM wave absorbers are manufactured based on the simulated results. As a result, the developed EM wave absorber for port logistics RFID system has the composition ratio of Amorphous metal powder(flake shape) : CPE = 87.5 : 12.5 wt.% and a thickness of 5.1 mm and, absorption ability is 22.5 dB in frequency band 433 MHz.