• 제목/요약/키워드: Side-lobe level

검색결과 113건 처리시간 0.024초

Ridge-Loaded Small Round-Ended Slot for Waveguide Slot-Array Antenna (도파관 슬롯 배열 안테나용 리지가 장하된 끝이 둥근 소형 슬롯)

  • Kim, Byung-Mun;Lee, Jong-Ig;Cho, Young-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • 제23권8호
    • /
    • pp.950-957
    • /
    • 2012
  • In this paper, a small round-ended slot loaded by double ridges on the broad wall of a rectangular waveguide is presented as an element for a waveguide slot-array antenna(WSAA). By properly adjusting the ridge dimension, a resonance of the slot at a desired frequency can be achieved. The resonant length of the proposed slot is about $0.26{\lambda}_0$(free space wave length) at the resonance frequency. The proposed resonant slot has some advantageous properties, such as small size, small resonant conductance, and short and stable resonant slot length. In addition, the characteristics of the slots are slightly affected by the adjacent elements when the slots are arrayed for a waveguide slot antenna. A $4{\times}1$ WSAA with -20 dB side-lobe level(SLL) is designed, fabricated, and tested experimentally. The measured results are well agreed with the simulated ones and have an SLL of -15.9 dB and a half-power beam width of $110.2^{\circ}$ in the E-plane and $21.2^{\circ}$ in the H-plane, respectively, at 9.41 GHz.

Correlation of the Neuropsychological Screening Battery (NSB) and Neuroanatomy for the Parkinson's Disease with Mild Cognitive Impairment by Using the Analysis of Cerebral Cortex Thickness in the Brain MRI (뇌 자기공명영상에서 대뇌 피질 두께 분석법을 이용한 파킨슨병의 경도인지장애 신경심리검사와 신경해부학적 상관관계)

  • Lee, Hyeonyong;Park, Hyonghu;Lee, Jaeseung;Im, Inchul
    • Journal of the Korean Society of Radiology
    • /
    • 제8권4호
    • /
    • pp.163-170
    • /
    • 2014
  • This study is to investigate neuro-anatomical correlation between neuropsychological results and cerebral cortex thickness of cognitive ability in the brain MRI targeting the patients with mild cognitive impairment. It was that 78 people who were diagnosed as first Parkinson's disease followed by neuropsychological screening battery(Parkinson's disease with mild cognitive impairment: 39 people; Parkinson's disease with normal cognition: 39 people) and 32 people of normal group were selected. Correlation between mild cognitive impairment and normal cognitive impairment and correlation between neuropsychological screening battery and cerebral cortex thickness in the brain MRI were performed by independent sample t-test or Pearson correlation coefficient and then level of significance of collected data was verified in p<0.05. As a result, cerebral cortex thickness of the Parkinson's disease with mild cognitive impairment in both side precuneas and right inferiortemporal lobe had statistically significant decrease. In addition, function of visuospatial ability, verbal and visual memory was reduced in neuropsychological screening battery for cognitive assessment. Especially, there was correlation between neuropsychological screening battery of verbal and visual memory anatomical left precuneus.

Analysis of TTD Phase Delay Error and Its Effect on Phased Array Antenna due to Impedance Mismatch (위상 배열 안테나 임피던스 부정합에 따른 실시간 지연회로의 위상 지연 오차 및 영향 분석)

  • Yoon, Minyoung;Nam, Sangwook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • 제29권11호
    • /
    • pp.828-833
    • /
    • 2018
  • It is well known that reflected waves and resonance affect phase distortion. In addition, phase delay can be distorted by antenna impedance. In this study, we analyze the phase delay variation caused by the antenna impedance, considering mutual coupling effects. In addition, we confirm the beam steering characteristics. When was -10 dB and -7 dB, the maximum phase delay error was $18.5^{\circ}$ and $26.5^{\circ}$, respectively. The Monte Carlo simulation with an eight-element linear array antenna demonstrated that the RMS error of the beam steering angle ranged from $0.19^{\circ}$ to $0.4^{\circ}$, and the standard deviation ranged from $0.14^{\circ}$ to $0.33^{\circ}$ when the beam steering angle was in the range of $0^{\circ}$ to $30^{\circ}$, with the uniformly distributed phase error of $18.5^{\circ}$ and $26.5^{\circ}$. The side lobe level increased from 0.74 dB to 1.21 dB by the phase error from the theoretical value of -12.8 dB, with a standard deviation of 0.31 dB to 0.51 dB. This is verified by designing an eight-element spiral array antenna.