• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.197-202
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• 2018

This paper reveals the impact of the insertion of electromagnetic band gap (EBG) structures on the performance of circularly polarized (CP) patch-slot antenna with offset slot. Several optimizations are necessary to precise physical parameters in the aim to fix the resonance frequency at 3.2 GHz. The proposed antenna possesses lightweight, simplicity, low cost, and circular polarization ensured by two feeding sources to permit right-hand and left-hand circular polarization process (RHCP and LHCP). The measured results compared with simulation results of the proposed circularly polarized EBG antenna with offset slot show good band operations with –10 dB impedance bandwidths of 9.1% and 36.2% centered at 3.2 GHz, which cover weather radar, surface ship radar, and some communications satellites bands. Our investigation will confirm the simulation and experimental results of the EBG antenna involving new EBG structures.

• Current Optics and Photonics
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• 제7권2호
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• pp.147-156
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• 2023

Circularly polarized (CP) emission can be achieved by integrating emissive materials into chiral metasurfaces. Such CP light sources in integrated device platforms are desirable for important potential applications. However, the exact characterization of the polarization state in CP emission may include some errors because of the unwanted polarization distortion caused by optical components (e.g., beam splitter) in the optical setup. Here, we consider CP emission measurements from chiral metasurfaces and characterize the polarization distortion caused by the beam splitter. We first detail the procedures for the Stokes parameters and Mueller matrix measurements. Then, we directly measure the Mueller matrix of the beam splitter and retrieve the original polarization state of CP emission from our metasurface sample. Using the measured Mueller matrix of the beam splitter, we specifically identify what contributes to polarization distortion in CP emission. Our work may provide useful guidelines for the characterization and compensation of polarization distortion in general Stokes parameter measurements.

• 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.

• Current Optics and Photonics
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• 제6권1호
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• pp.23-31
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• 2022

Heterodyne efficiency is an indicator to evaluate the performance of space coherent laser communication systems. It is affected by signal light and local oscillator (LO) light amplitude, phase and polarization state. In this paper, based on the common heterodyne efficiency, a heterodyne efficiency model that can reflect polarization aberration of optical system is proposed. The heterodyne efficiency is analyzed when the signal light and the LO light are linearly polarized or circularly polarized. For a coherent communication optical system, when the incident signal light is right-circularly polarized light and the incident LO light is 45° linear polarized light. Based on the three-dimensional ray tracing theory and the heterodyne efficiency proposed in this paper, the change of polarization states and the distribution of heterodyne efficiency of the signal light and LO light influenced by the optical system's polarization aberration are analyzed. Analysis shows that the heterodyne efficiency model proposed in this paper can be used to evaluate coherent communication systems and reflect the influence of optical system polarization aberration.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.441-444
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• 2008

This paper describes the development of a circularly polarized microstrip antenna, as a part of the Circularly Polarized Synthetic Aperture Radar (CP-SAR) sensor which is currently under developed at the Microwave Remote Sensing Laboratory (MRSL) in Chiba University. CP-SAR is a new type of sensor developed for the purpose of remote sensing. With this sensor, lower-noise data/image will be obtained due to the absence of depolarization problems from propagation encounter in linearly polarized synthetic aperture radar. As well the data/images obtained will be investigated as the Axial Ratio Image (ARI), which is a new data that hopefully will reveal unique various backscattering characteristics. The sensor will be mounted on an Unmanned Aerial Vehicle (UAV) which will be aimed for fundamental research and applications. The microstrip antenna works in the frequency of 1.27 GHz (L-Band). The microstrip antenna utilized the proximity-coupled method of feeding. Initially, the optimization process of the single patch antenna design involving modifying the microstrip line feed to yield a high gain (above 5 dBi) and low return loss (below -10 dB). A minimum of 10 MHz bandwidth is targeted at below 3 dB of Axial Ratio for the circularly polarized antenna. A planar array from the single patch is formed next. Consideration for the array design is the beam radiation pattern in the azimuth and elevation plane which is specified based on the electrical and mechanical constraints of the UAV CP-SAR system. This research will contribute in the field of radar for remote sensing technology. The potential application is for landcover, disaster monitoring, snow cover, and oceanography mapping.

• 한국전자파학회논문지
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• 제14권2호
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• pp.133-138
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• 2003

본 논문에서는 비가시거리(NLOS) 전파환경에서 원형편파를 송신하고 수직, 수평편파 안테나로 수신하는 원형편파 다이버시티(CV-CH)방식에 대하여 이론적 모델을 제시하고 이의 우수성을 확인하였다. 원형편파 다이버 시티에 대한 간단한 이론적 모델을 통하여 XPD에 대한 상관계수 평가식을 유도하였으며, 비가시거리 전파환경에서 원형편파다이버시티 경우 직선편파다이버시티(VV-VH) 경우보다 교차편파분리도(XPD)가 약 6~7 dB 정도 낮게 됨을 알 수 있었다. 그 결과 원형편파 다이버시티 경우의 상관계수는 기존의 직선 편파다이버시티보다 더 낮은 상관계수 값을 나타내는 이론적 모델을 제시하였고 측정된 결과로부터 이의 성능을 확인하였다.

• 한국정보통신학회논문지
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• 제7권5호
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• pp.872-878
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• 2003

본 논문에서는 3D-Ray Tracing 기법을 이용한 옥내 무선통신용 편파발생 시뮬레이터를 개발하고, 실내 무선전파환경에서 실제 측정한 데이터와의 비교를 통하여 검증하였다. 개발된 시뮬레이터를 이용하여 Line-Of-Sight(LOS)와 Non-Line-Of-Sight(NLOS) 무선전파 환경에서 수직, 수평, 원편파에 대한 채널특성과 편파 다이버시티 수신특성을 해석하였다. 그 결과 원편파의 경우 기수회 반사파를 억제 수신하는 특성 때문에 수직 및 수평편파의 경우와 비교하여 다중경로 페이딩이 현저하게 경감됨을 알 수 있었다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.478-483
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• 2003

In this paper, in order to fabricate the circularly polarized diversity system which will mitigate multipath fading, 5.8GHz band microstrip array antenna were designed and fabricated. These antenna were designed using Ensemble 6.0 program and the fabricated antenna were vertical and horizontal polarized antenna, left-handed circularly polarized antenna, and right-handed circularly polarized antenna. The designed antenna parameters included S11 and impedance characteristics of fabricated antenna were measured using Network Analyzer(8753ES). From the measurement results, the S11 for each polarization antenna at resonance frequency of 5.8GHz band was showed -38dB, -44dB, and -50dB respectively and it was similar to the simulation result, and also the impedance can be matched at $50{\Omega}$. In order to compare polarization characteristics, broadband measurement was also conducted in this paper.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.37-41
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• 2019

A stack-ring configuration is proposed for designing a dual-band circularly polarized (CP) antenna. Each ring generates different resonant frequencies. A good CP performance at both resonant frequencies is achieved by adjusting the relative distance between the two rings. The two operating bands are separated with a small frequency ratio of 1.07. Measured results show that radiation patterns with good CP characteristics are obtained at the two resonant frequencies.

• 한국전자파학회논문지
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• 제13권9호
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• pp.851-857
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• 2002

본 논문에서는 두 스파이럴을 평면상에서 동위상으로 급전하여 원형편파의 전방향성 코니컬 빔을 가지는 접지면에 원형 슬롯이 있는 마이크로스트립 스파이럴 안테나를 제안하였다. 기존에 제시된 동위상으로 급전하는 방법은 복잡도가 높고 수직으로 급전해야 하는 문제가 있지만 제안된 구조는 스파이럴의 외각 부분에서 급전선의 길이만 동일하게 하여 간단히 동위상으로 급전할 수 있다. 원형 슬롯의 반지름이 23 mm일 때 5 GHz에서 6.5 GHz까지는 $\theta$ 방향으로 약 40$^{\circ}$로 최대복사가 일어나고 9 GHz에서 11 GHz까지는 약 58$^{\circ}$의 방향으로 최대 복사가 일어나는 코니컬 빔을 얻을 수 있다.