• Title/Summary/Keyword: phased array antennas

Search Result 73, Processing Time 0.023 seconds

Squint-less Phased Array Antenna Near-field Subwavelength Focusing with True-time Optical Delay Line (광 지연선로를 이용한 스퀸팅이 없는 위상배열 안테나의 근접장 서브파장 포커싱)

  • Jung, Young Jin
    • Korean Journal of Optics and Photonics
    • /
    • v.30 no.3
    • /
    • pp.94-100
    • /
    • 2019
  • The near-field subwavelength squint-less focusing system of a phased array antenna is designed and demonstrated by numerical simulation. The Huygens-Fresnel principle is applied to numerical simulation for calculation of the phased array antenna at microwave frequency. It was shown that beam squinting can be eliminated, utilizing true-time optical delay lines based on a chirped fiber grating in the proposed system. Furthermore, subwavelength focusing with high numerical aperture can be achieved by considering the fact that the array elements of the phased-array antenna can be treated as diffractive elements in an optical lens system. Also, side lobes can be suppressed by decreasing the distance between element antennas to less than half of the wavelength.

Detection Performance of Noncoherent Radar: MIMO Radar, Phased Array Radar, Directional MIMO Radar (비동기식 레이더의 검출 성능 비교: MIMO 레이더, 위상 배열 레이더, 지향성 MIMO 레이더)

  • An, Chan-Ho;Yang, Jang-Hoon;Pak, Ui-Young;Ryu, Young-Jae;Han, Duk-Chan;Kim, Dong-Ku
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.36 no.12B
    • /
    • pp.1752-1757
    • /
    • 2011
  • In a traditional phased array radar, closely spaced antenna elements transmit a scaled version of single waveform to maximize the signal energy. On the contrary, a multiple-input multiple-output (MIMO) radar consists of widely separated antennas and transmits an arbitrary waveform from each antenna element. These waveforms and spatial diversity enable superior capabilities compared with phased array radar. At high signal-to-noise ratio (SNR), the detection performance of the MIMO radar is better than the phased array radar due to the diversity gains. However, the phased array radar outperforms the MIMO radar at low SNR, due to the energy maximization. In this paper, we investigate the compromised scheme between the MIMO radar and the phased array radar. Employing the MIMO radar equipped with phased array elements, the compromised scheme achieves both array gain and diversity gain. Also, we compare the performance degradation when the steering direction is incorrect.

A Study on Fault Diagnosis for Planar Active Phased Array Antenna (평면 능동위상배열안테나 결함소자 진단방법에 관한 연구)

  • Jin-Woo Jung;Seung-Ho Kang
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.18 no.1
    • /
    • pp.11-22
    • /
    • 2023
  • A radiating elements fault diagnosis method with simplified radiation pattern measurement procedure was presented for planar active phased array antenna system. For presenting the mentioned method, the technique for linear approximation based on the radiation characteristics of a planar array configuration and a technique for solving a unique solution problem that occur in process of diagnosing a fault in a radiating elements were presented. Based on the presented method and a genetic algorithm, experimental simulations were performed for radiating element defect diagnosis according to various planar active phased array antenna configurations. As a result, it was confirmed that the presented radiating element fault diagnosis method can be smoothly applied to planar active phased antennas having various configurations.

Compensation of a Squint Free Phased Array Antenna System using Artificial Neural Networks

  • Kim, Young-Ki;Jeon, Do-Hong;Park, Chiyeon
    • International Journal of Fuzzy Logic and Intelligent Systems
    • /
    • v.4 no.2
    • /
    • pp.182-186
    • /
    • 2004
  • This paper describes an advanced compensation for non-linear functions designed to remove steering aberrations from phased array antennas. This system alters the steering command applied to the antenna in a way that the appropriate angle commands are given to the array steering software for the antenna to point to the desired position instead of squinting. Artificial neural networks are used to develop the inverse function necessary to correct the aberration. Also a straightforward antenna steering function is implemented with neural networks for the 9-term polynomials of forward steering function. In all cases the aberration is removed resulting in small RMS angular errors across the operational angle space when the actual antenna position is compared with the desired position. The use of neural network model provides a method of producing a non-linear system that can correct antenna performance and demonstrates the feasibility of generating an inverse steering algorithm.

Phased Array Behavior of the Coupling of the Millimeter Wave Second Harmonic Oscillator (밀리미터파 대역 제2고조파 발진기 결합계의 위상차 배열 동작)

  • Choi, Young-Kyu;Kim, Gi-Rae
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.64 no.3
    • /
    • pp.438-444
    • /
    • 2015
  • A new approach to the active phased arrays for the second harmonic generation is presented. Phase variation between the second harmonic oscillators by the mutual synchronization is analyzed theoretically. In this coupling, the active antenna consists of the FET oscillator which plays two roles in fundamental oscillation and frequency multiplying, and the patch antenna resonated at the second harmonic frequency. The radiated second harmonic wave was scanned by varying the free-running oscillation frequencies of the active antennas. In the experiment using the 2-elements array and the 4-elements array, the radiated beam of the second harmonic wave was scanned more widely compared with the case of the fundamental wave radiation.

A Study on the Radiation Characteristics of Linear phased array antenna using current divider. (전류 분배기를 이용한 선형위상배열 안테나에 관한 연구)

  • 이창식;유재문;이종악
    • Proceedings of the Korean Institute of Intelligent Systems Conference
    • /
    • 2000.11a
    • /
    • pp.419-427
    • /
    • 2000
  • The 4 by 4 microstrip phased array antenna designed and radiation characteristics are studied. The design frequency was chosen to be 5.8GHz. Chebyshev ratio was achieved by unequal power divider and Wilkinson power divider. The ratio of current at each port is 1 : 2.6 : 2.6 : 1 and then side lobe level is less than -30 dB. It is shown that the radiation beam direction can be changed up to 30。 by control the phase at each port. The result can be used to design electrically controllable microwave scanning antennas.

  • PDF

A Study on the Impedance Matching of Phased Array Antennas (위상배열 안테나의 임피던스 정합에 관한 연구)

  • 하헌태;김세윤
    • Journal of the Korean Institute of Telematics and Electronics A
    • /
    • v.29A no.2
    • /
    • pp.24-32
    • /
    • 1992
  • The impedance matching properties of infinite planar arrays of rectangular waveguides with dielectric plug loading and sheath covering are studied here. The effects of several involved parameters on the impedance matching of the phased array antenna are investigated by calculating the reflection coefficients numerically. The improvement of impedance matching and the appearance of forced surface wave resonances are also discussed.

  • PDF

Optical True-Time Delay for High-Directivity Phased Array Antennas (고 지향성 위상 배열 안테나를 위한 실시간 지연선로)

  • 배덕희;신종덕;김부균
    • Proceedings of the Optical Society of Korea Conference
    • /
    • 2003.02a
    • /
    • pp.318-319
    • /
    • 2003
  • 이동통신 시스템에서 데이터, 음성, 영상신호를 효율적으로 전송하기 위해 위상 배열 안테나(Phased-Array Antenna: PAA)에 관한 연구가 최근 국내외적으로 활발히 진행되고 있다. 광통신 기술을 이용한 PAA용 실시간 지연선로 (True Time-Delay: TTD)는 넓은 대역폭, 저 손실, 전자파 간섭에 무관, 소형화, 특히 ‘beam squintr´ 현상이 없는 장점이 있기 때문에 각광을 받고 있다. 특히, 신호의 간섭을 줄이기 위해 안테나 방사 패턴의 부엽 (side lobe)의 크기를 감소시킬 수 있는 안테나 설계기술이 필요하다. (중략)

  • PDF

A Study on the Control of Asymmetric Sidelobe Levels and Multiple Nulling in Linear Phased Array Antennas (선형 위상 배열 안테나의 비대칭 Sidelobe 레벨 제어 및 다중 Nulling에 관한 연구)

  • Park, Eui-Joon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.20 no.11
    • /
    • pp.1217-1224
    • /
    • 2009
  • This paper newly proposes a methodology towards computing antenna element weights which are satisfying asymmetric sidelobe levels(SLLs) specified arbitrarily on both sides of the main beam pattern, in the linear phased array antenna pattern synthesis problem. Opposite to the conventional methods in which the element weights are directly optimized from the array factor, this method is based on the optimum perturbations of complex roots inherent to the Schelkunoff's polynomial form which is described for the array factor. From the proposed methodology, the capability of nulling the directions of multiple jammers is also possible by independently perturbing only the complex roots corresponding to each jamming direction, hence allowing an enhancement of the simplicity of the numerical procedure by means of a proper reduction of the dimension of the solution space. The complex weights over the array are then easily computed by substituting the optimally perturbed complex roots to the Schelkunoff's polynomial. Some examples are examined and numerically verified by substituting the extracted weights into the array factor equation.

Optical true time-delays for phased-array antennas using 2×2 MEMS switches and fiber delay lin (2×2 MEMS 스위치와 광섬유 지연선로를 이용한 위상배열 안테나용 실시간 지연선로)

  • Lee, Gab-Yong;Choi, Yeon-Bong;Shin, Jong-Dug;Kim, Boo-Gyoun
    • Korean Journal of Optics and Photonics
    • /
    • v.13 no.4
    • /
    • pp.289-294
    • /
    • 2002
  • We propose optical true time-delays (TTDs) for phased-array antennas (PAAs) composed of 2${\times}$2 MEMS switches and fiber delay lines, and implement a TTD which shows a maximum scan angle of $120^{o}$ with $30^{o}$ resolution. Since this structure uses only one fixed wavelength laser diode, it provides several advantages such as easy control, high speed operation, and low cost compared with those of the optical TTDs using tunable laser sources. We design a four element linear PAA using the proposed TTDs at 10 ㎓. Simulation results show that the maximum gain is 11.6 dB at the radiation angle $0^{o}$, 11.2 dB at $\pm$$30^{o}$, and 10.6 dB at $\pm$$60^{o}$.