• Title/Summary/Keyword: Patch size

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Effect of Linear Development Projects on Forest Fragmentation in the Nakdong River Watershed (낙동강 유역의 선형개발사업이 산림 단편화에 미치는 영향)

  • Jung, Sung-Gwan;Park, Kyung-Hun;Oh, Jeong-Hak
    • Journal of Environmental Impact Assessment
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    • v.11 no.3
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    • pp.117-127
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    • 2002
  • This study tested the usefulness of landscape indices for quantifying forest fragmentation due to linear development projects. Research was carried out in the middle-upper Nakdong River watershed, which has been affected by the expressway building, or national road-widening. Landscape indices were calculated from the forest cover maps before and after road-building using FRAGSTATS 3.1. We could successfully demonstrate the forest fragmentation based on landscape indices; (1) patch size decreased, and edge density and patch density increased (2) roads simplified patch shapes, especially in the larger patches, (3) patch core area size decreased, and core area density increased, (4) the distance increased between the focal patch and each of the other patches within the search radius (=1km) as a result of roads. We suggest several important needs for future researches, including continued investigation of scaling issues, development of indices that measure specific components of spatial pattern, and study of the relationships between forest fragmentation and ecological processes.

Front-to-Back Ratio Improvement of a Microstrip Patch Antenna Loaded with Soft Surface Structure in a Partially Removed Ground Plane

  • Lee, Hong-Min
    • Journal of electromagnetic engineering and science
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    • v.12 no.4
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    • pp.247-253
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    • 2012
  • This study presents a new, simple method for improving the front-to-back (F/B) ratio of a microstrip patch antenna. The back radiation of the microstrip patch antenna is reduced by removing some metallic parts around the ground plane and placing a new soft-surface configuration, consisting of an array of stand-up split-ring resonators on a bare dielectric substrate near the two ground plane edges. Compared to the F/B ratio of a conventional microstrip patch antenna with a full ground plane of the same size, our proposed microstrip patch antenna experimentally achieves an improved F/B ratio of 9.6 dB.

Dual-Band Microstrip Patch Antenna with Switchable Orthogonal Linear Polarizations

  • Kim, Jeongin;Sung, Youngje
    • Journal of electromagnetic engineering and science
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    • v.18 no.4
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    • pp.215-220
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    • 2018
  • This study presents a dual-band polarization-reconfigurable antenna that comprises a large square patch with a pair of corner-cut edges and two small square patches with a shorting via. Two PIN diodes are located between the large square patch and two small square patches. Depending on the bias state applied to the two PIN diodes, each small patch may be disconnected or connected to the large square patch. As a result, the proposed antenna can provide polarization reconfigurability between two orthogonal linear polarizations. Further, the proposed antenna operates at 2.51 GHz and 2.71 GHz. From the measured results, the proposed antenna shows a 10 dB bandwidth of 2.39% (2.49-2.55 GHz) and 2.58% (2.68-2.75 GHz). In this work, the frequency ratio can be easily controlled by changing the size of the small patch.

A Side-Fed Circularly-Polarized Patch Antenna with a Dielectric Loading

  • Jeong, Ji-Young;Choi, Seung-Mo;Enkhbayar, Bayanmunkh;Sodnomtseren, Ononchimeg;Ahn, Bierng-Chearl
    • Journal of electromagnetic engineering and science
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    • v.7 no.3
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    • pp.122-128
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    • 2007
  • In this paper, we present the design and measurement of a side-fed circularly-polarized patch antenna with a dielectric loading. The antenna consists of a comer-truncated rectangular patch, an L-shaped ground plane, a dielectric loading material, and a coaxial probe. An antenna operating at the UHF band (910 MHz) for the RFID reader applications is optimized using a commercial software. The size of the patch is reduced by a factor of 1.73 by loading the patch with mono-cast(MC) nylon. Measurements of the fabricated antenna show performance characteristics comparable to those of much larger commercial RFID reader antennas.

Tool Path Generation of Multi-Patch Sculptured Surface with Reparameterization (여러 개의 패치로 이루어진 곡면에서 재매개변수화를 통한 공구경로 생성)

  • 이성근
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.04a
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    • pp.647-652
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    • 2000
  • Recently, according to the various taste of consumers, the design of a product is changed variously and complicatedly. The complicated product is not usually constructed with one patch but multi-patch. By the way, in machining, higher precision and the reduction of leading and machining time is required. But for the multi-patch sculptured surface, the amount of machining data becomes large. This means the increase of leading and machining time. In this study, the tool path generation method with reparameterization is proposed for multi-patch sculptured surface and variable step size using NURBS is used to satisfy the precision and to reduce leading and machining time.

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Fast Orthorectification for High Resolution Satellite Images Using Quadtree-Based Patch Backprojection

  • Chen, Liang-Chien;Teo, Tee-Ann;Rau, Jiann-Yeou
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.687-689
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    • 2003
  • High resolution satellite images have huge amount of pixels in common. Thus, an efficient method is required for the generation of orthoimages. Patch backprojection method is a feasible way to improve the efficiency with respect to the point-by-point patch backprojection. We will propose an Adaptive Patch that optimizes the patch size for different terrain variations. The essence of the patch optimization is quadrate structuring for terrain variations. The area of interest is, thus, sequentially subdivided to four quadrate tiles until a preset criterion is met. The experiment results indicated that the proposed method is efficient without losing accuracy.

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Detection of edge delamination in surface adhered active fiber composites

  • Wang, Dwo-Wen;Yin, Ching-Chung
    • Smart Structures and Systems
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    • v.5 no.6
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    • pp.633-644
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    • 2009
  • A simple method has been developed to detect the bonding condition of active fiber composites (AFC) adhered to the surface of a host structure. Large deformation actuating capability is one of important features of AFC. Edge delamination in adhesive layer due to large interfacial shear stress at the free edge is typically resulted from axial strain mismatch between bonded materials. AFC patch possesses very good flexibility and toughness. When an AFC patch is partially delaminated from host structure, there remains sensing capability in the debonded part. The debonding size can be determined through axial resonance measured by the interdigitated electrodes symmetrically aligned on opposite surfaces of the patch. The electrical impedance and modal response of the AFC patch in part adhered to an aluminum plate were investigated in a broad frequency range. Debonding ratio of the AFC patch is in inverse proportion to the resonant frequency of the fundamental mode. Feasibility of in-situ detecting the progressive delamination between AFC patch and host plate is demonstrated.

Radially Corrugated Circular Microstrip Patch Antenna for Miniaturization (소형화를 위한 방사 주름 원형 마이크로스트립 패치 안테나)

  • 이성민;김종래;우종명
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.12
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    • pp.1233-1238
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    • 2003
  • In this paper, radially corrugated circular-type microstrip patch antenna was devised and manufactured for GPS (center frequency: 1.575 GHz). Radially corrugated circular-type microstrip patch antenna having radiational corrugation-patch contributed to add size reduction ratio by lowering the resonant frequency because the edge current also has the extended and perpendicular path. As a result, radially corrugated circular-type microstrip patch antenna has 28 % area reduction than planer circular-type patch antenna for linear polarization and 27.7 % area reduction than planer circular-type patch antenna for circular polarization. Radially corrugated circular-type microstrip patch antenna is suitable for miniaturized receive antenna for GPS which has the characteristic of gain 2.1 dBd, axiai ratio 1.3 dB, 2 dB axial bandwidth 15 MHz(0.9 %).

Study for the Size Reduction of Microstrip Patch Antenna using Corrugation (주름 구조를 이용한 마이크로스트립 패치 안테나의 소형화에 대한 연구)

  • 송무하;우종명
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.2
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    • pp.192-201
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    • 2003
  • In this paper, to reduce the size of patch, three types of 3-dimensional patch antennas which are one-directionally-corrugaged type, rectangular ring-likely corrugated type, and lattice-likely corrugated type rectangular microstrip patch antennas(MPA) are designed and fabricated at the 1.575 GHz. As the result, one-directionally corrugated rectangular MPA is reduced in the resonant length of patch by 21.4% than that of general plane MPA. -10 dB bandwidth(B.W) is 62 MHz(3.9 %) and this is broader than that(39 MHz, 2.5 %) of plane MPA by 23 MHz(1.5 %). The gain is 5.8 dBd and this is reduced by 0.9 dB than that(6.7 dBd) of plane MPA. Half power beamwidth(HPBW) is broadened by 18$^{\circ}$ than that of plane MPA in the E-plane and this is due to the reduced length of patch. For rectangular ring-likely corrugated retangular MPA, the patch size is miniaturized by 21.6 % than that of plane MPA. For lattice-likely corrugated rectangular MPA, in the linear polarization, the size of patch is miniaturized by 43.3 % than that of plane MPA. -10 dB B.W is 70 MHz(4.4 %) and this is broadened than that of plane MPA by 31 MHz(2 %). Gain is 2.2 dBd and this is smaller than that of plane MPA by 4.5 dB. HPBW is increased in both E-plane and H-plane by 22$^{\circ}$ and 13$^{\circ}$, respectively. For circular polarization, the size of patch is reduced by 41 % than that by 41 %. The axial ratio(AR) is 0.8 dB at the 1.575 GHz and the axial ratio bandwidth(ARBW) within 2 dB is 20 MHz(1.27 %) and this is increased by 10 MHz(0.63 %) than that 10 MHz(0.63 %) of plane MPA. From all the results above, it is conformed that the proposed antenna has merit in size reduction of patch and in the input impedance B.W, and is more profitable in many application than the general plane type MPA.

Miniaturization of Microstrip Antenna using Iris (Iris를 이용한 마이크로스트립 안테나의 소형화)

  • Seo Jeong-Sik;Woo Jong-Myung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.10 s.89
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    • pp.922-930
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    • 2004
  • In this paper, the 3-dimensional microstrip antenna, where the lis is attached near the patch, on the pound and both patch and ground in zigzag, is designed and fabricated to miniaturize size of antenna. The path of surface current and permittivity in patch are increased because of attached Iris near the patch, on the pound and patch and found. In particula., the maximum size reduction effect among the three-type of $79.1\%$(17 mm$\times$90 mm) was presented in zigzag-type compared with the rectangular microstrip patch antenna(MPA) with a height of 9 mm at the resonant frequency of 1.575 GHz. The gain showed -1.15 dBd, -10 dB bandwidth showed 6.2$\%$(98 MHz), and HPBW of E-plane showed $154^{\circ}$. As that result we could confirm that the 3-dimensional structure with attached Irises is the proper form for the miniaturization of microstrip antenna.