• Current Optics and Photonics
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• 제7권2호
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• pp.157-165
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• 2023

We propose a highly directional waveguide grating antenna for an optical phased array, achieving high directionality of more than 97% by interleaving the trenches with different etching depths in the silicon nitride layer, and adopting a multilayered structure. Meanwhile, the multilayered structure reduces the perturbation strength, which enables a centimeter-scale radiation length. The beam-steering range is 13.2°, with a wavelength bandwidth of 100 nm. The 1-dB bandwidth of the grating is 305 nm. The multilayered grating structure has a large tolerance to the fabrication variation and is compatible with CMOS fabrication techniques.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제11권5호
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• pp.806-812
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• 2000

In this paper, we theoretically studied on the large antenna array whose element had wider than one wavelength. And we also verified the adaptedness through the experiments. Using grating lobes, we could make antenna have sharp HPBW. Not only HPBW but also SLL could be controlled by giving optimal space for antenna array. In order to verify this method, we designed 4 horn antenna array and measured the radiation patterns at 9 GHz. Each horn antenna has the dimension of 64.3$\times$82.5$\textrm{mm}^2$ and HPBW of 27$^{\circ}$. The space between antennas is longer than one wavelength so that it may have the grating lobes in visible region. As a result of experiments, we could get HPBW of 4.3$^{\circ}$, 3.3$^{\circ}$ and 1.7$^{\circ}$when giving 2.5λ, 2.7λ and 3.0λ of the spacing respectively. We concluded this could be useful making the antenna with narrow HPBW.

• Journal of the Korean Institute of Telematics and Electronics A
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• 제28A권10호
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• pp.799-805
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• 1991

In this paper, the analysis and design of a spirally slotted array antenna with high efficiency are presented. Electric fields in the slots are calculated by electromagnetic fields in the upper waveguide and radiation field equations are derived. Slots are arrayed spirally on the upper circular plate of twofold radial waveguide. In order to suppress grating lobes from the array, a slow wave structure is inserted in the upper waveguide. This antenna is characterized by a good circular polarization, high efficiency of 75 percent and grating lobes below -34dB.

• Current Optics and Photonics
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• 제3권6호
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• pp.522-530
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• 2019

We present simulation methods to accurately determine the transmission efficiency and far-field patterns (FFPs) of a shallow-etched waveguide grating antenna (WGA) formed on a silicon-on-insulator wafer based on the finite-difference time-domain (FDTD) approach. The directionality and the FFP of a WGA with >1-mm in length can be obtained reliably by simulating a truncated WGA structure using a three-dimensional FDTD method and a full-scale WGA using a two-dimensional FDTD with the effective index method. The developed FDTD methods are applied to the simulation of an optical phased array (OPA) composed of a uniformly spaced WGA array, and the steering-angle dependent transmission efficiency and FFPs are obtained in OPA structures having up to 128-channel WGAs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제10권4호
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• pp.594-606
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• 1999

The electromagnetic scattering characteristics by a periodic strip grating on a grounded dielectric slab for TE polarization case is examined from the viewpoints of both the reflection grating and the leaky wave antenna problems. Numerical results for two kinds of Bragg blazing (resonance type and non-resonance type) phenomena are given and some discussions on the properties such as complex propagation constants, scattering characteristics, and distributions of strip current density are presented.

• Korean Journal of Optics and Photonics
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• 제30권3호
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• pp.94-100
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• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제11권8호
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• pp.1363-1375
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• 2000

The electromagnetic scattering characteristics by a periodic strip grating on a grounded dielectric slab for TM polarization case are examined from the viewpoints of both the reflection grating and the leaky wave antenna problems. Numerical results far two kinds of Bragg blazing (resonance type and non-resonance type) phenomena are given and some discussions on the properties(complex propagation constants, scattering characteristics, and distributions of strip current density) are presented. The comparison of the Bragg blazing phenomena between TM and TE polarization cases are also given in detail.

• Journal of the Korean Institute of Telematics and Electronics A
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• 제33A권10호
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• pp.90-97
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• 1996

A numerical method for scattering of electromagnetic waves from a periodic strip grating over a grounded dielectric slab is considered for TE and TM polarization cases from the viewpoints of both reflection grating problem and leaky wave antenna problem. The analysis is based on a mode expansion method, floquet's theorem, and the method of moments. Numerical results involving some combinations of geometric parameters are presented in terms of complex propagation constant (kd-$\beta$d diagram), radiation pattern, and relative scattered powers of spectral modes. In particular, the relationship between complex propagatio constnat form the viewpoint of leaky wqve antenna problem and Off-bragg and bragg blazing phenomena from the viewpoint of reflecton graing problem is investigated.

• Journal of electromagnetic engineering and science
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• 제1권2호
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• pp.161-165
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• 2001

The radiation characteristics of leaky wave emanated from finite strip-grating loaded dielectric coated coaxial waveguide with finite periodic thick slots are investigated theoretically. The rigorous integral equations are derived for the proposed structure using the courier transform, mode expansion, and sine series expansion of the electric current on metallic strips, and the simultaneous linear equations are obtained. The effects of finite strip-grating loading on a dielectric-coated coaxial waveguide with finite periodic thick slots are examined in terms of radiation characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제12권2호
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• pp.193-198
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• 2001

접지된 유전체슬랩 위에 주기적으로 스트립이 놓여있는 격자구조에 대한 전자파 산란현상을 반사격자(reflection grating) 관점과 누설파안테나(leaky wave antenna) 관점에서 조사하였다. 수치해석 결과로 입사파의 편파에 무관한 Bragg blazing 현실과 동시에 Bragg 및 off-Bragg blazing 현상이 확인되는 경우를 조사하였으며 그 특성(복소전파상수, 복사패턴, 산란특성)에 대하여 논의하였다.