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

• ETRI Journal
• /
• 제33권2호
• /
• pp.163-168
• /
• 2011

A Fabry-Perot cavity (FPC) antenna producing both high-gain and circularly-polarized (CP) behavior is proposed. To increase antenna gain and obtain CP characteristics, a superstrate composed of square patches with a pair of truncated corners is placed above the linearly polarized patch antenna with an approximately half-wavelength distance from the ground plane at the operating frequency. The proposed antenna has the advantages of high gain, a simple design, and an excellent boresight axial ratio over the operating frequency bandwidth. Moreover, used in an FPC antenna, the proposed superstrate converts a linear polarization produced by a patch antenna into a circular polarization. In addition, the cavity antenna produces left-hand circular-polarization and right-hand circular-polarization when a patch antenna inside the cavity generates x-direction and y-direction polarization, respectively. The measured and simulated results verify the performance of the antenna.

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

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

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
• /
• pp.609-612
• /
• 2003

For combating multipath fading in wireless radio environment, diversity schemes is useful. In this paper, for performance improvement of polarization diversity system, we analyzed a two-branch polarization diversity at the receiving end of a mobile link when the transmitter emits a circularly polarized wave. And In order to calculate the correlation coefficient considering the XPD(cross polarization discrimination) between the received signals for the two diversity branches, a simple theoretical model of circular polarization diversity is adopted and calculate correlation coefficient. From the analysis results, it is seen that the correlation coefficient of circular polarization diversity evaluated by the XPD is less than that of vertical polarization diversity. And also, we designed and fabricated circular polarization diversity system with microstrip antenna. we analyzed data measured in indoor NLOS environment using fabricated circular polarization diversity system. From the measurement results, it is clearly seen that the diversity effect of circular polarization diversity system is higher 3dB than vertical polarization diversity system.

• 한국전자파학회논문지
• /
• 제23권2호
• /
• pp.144-150
• /
• 2012

본 논문에서는 ITS(Intelligent Transport System)의 DSRC(Dedicated Short Range Communication) 통신을 위한 노변 기지국용 원형 편파 패치 배열 안테나를 제안하였다. DSRC 노변 기지국용 안테나가 다중 경로로부터 반사된 신호를 효율적으로 수신하기 위해 원형 편파로 동작하도록 설계하였다. 제안된 안테나는 마이크로스트립 패치와 급전 선로로 구성되었으며, 급전부의 슬롯 부근에 슬릿을 삽입하여 원형 편파를 발생시켰다. DSRC 노변 기지국용 안테나에 요구되는 이득 값을 만족시키기 위해 $2{\times}2$ 배열 구조로 설계하였다. 측정된 임피던스 대역폭과 축비 대역폭은 5.795~5.855 GHz의 DSRC 통신 대역을 모두 만족하였다. 제안된 안테나의 수직 반치각과 수평반치각은 약 $43^{\circ}$이며, 약 11.21 dBi의 이득 특성을 보였다.

• 한국전기전자재료학회논문지
• /
• 제17권7호
• /
• pp.776-781
• /
• 2004

We report the performance of a four-element, 11.67 GHz, $high-{T}_c$ superconducting (HTS) microstrip antenna array with corporate feed network. The HTS antenna array used in this work had a circular polarization for direct broadcasting satellite (DBS) system. Our array antennas were designed and built on a 0.5 mm thick MgO substrate. To compare the superconducting antennas with normal conducting counterpart, One antenna pattern was fabricated from gold thin film, and a second pattern was fabricated from ${YBa}_2{Cu}_3{O}_7-x(YBCO)$ superconducting thin film. To improve the axial ratio of circularly polarized arrays, sequential rotation technique were used. Efficiency, radiation pattern, return loss and bandwidth were measured for both antennas at cryogenic temperature and room temperature. The array produced good circular polarization, and the gain of the array at 77 K, relative to a copper array at room temperature was approximately 1.54 dB. The measured return loss of our HTS antenna array was 35.79 dB at the resonant frequency of 11.67 GHz and The total effective bandwidth was about 3.4 %. The results showed that high-temperature superconductors, when used in microstrip arrays, improved the efficiency of the HTS antenna array for circularly polarization.

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

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

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2014년도 춘계학술대회
• /
• pp.682-685
• /
• 2014

본 논문에서는 센서노드용 원형편파 안테나의 설계하였다. 확률론적 방법인 Particle Swarm Optimization(PSO) 알고리즘과 Adaptive Particle Swam Optimization(APSO) 알고리즘을 구현하고 성능비교를 통해 안테나 최적설계에 적합한 알고리즘을 결정하였다. PSO는 41번, APSO는 27번의 계산 결과 수렴을 하였다. 두 알고리즘 모두 최적설계에서 목표값을 모두 만족을 하였으나 수렴도에서 APSO가 빠르게 수렴한 것을 확인할 수 있었다.