• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1676-1679
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• 2003

A perfect matching is the desire of antenna designers. In this paper, we improve the matching of antenna designing. In general, the efficiency of antennas has many improvements. In this paper, we choose to extend matching by adding the slots in the basic microstrip-fed rectangular slot antenna. We called it as "parasitic slots". The dominant characteristic of this addition is double efficient improvement matching and other characteristics of antenna are similar. It means that the microstrip-fed rectangular slot antenna with parasitic slots has all characteristics as same as the microstrip-fed rectangular slot antenna without parasitic slots. The antenna with parasitic slots has better matching better than the antenna without parasitic slots.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.260-267
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• 2003

The wideband characteristics of planar antennas with a wide radiating slot have been examined in this paper. A various resonance modes are generated in the wide slot and the wideband characteristics are enhanced by impedance match at each resonance frequencies. In this process, the geometry effects on the impedance match were extracted and it was found that a round corner rectangular slot antenna has more stable impedance match over a wide frequency range than a normal rectangular slot antenna. The round corner rectangular slot antenna is fabricated to verify the wideband characteristics and its measured bandwidth is almost 2 octaves(2.08 ㎓~8.25 ㎓) with VSWR$\leq$2.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.257-262
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• 2002

A single-layered radial line slot array (SL-RLSA) antenna etched on a substrate and fad by a rectangular waveguide is presented in the 60 ㎓ band. The design curves are obtained by an efficient electromagnetic coupling analysis using Ewald Sum technique and Shanks transformation. The antenna has rectangular waveguide feed structure using a rectangular waveguide-to-radial line transition. The prototype antenna of 10 cm-diameter was tested and the gain of 31 ㏈i and the efficiency of 38% were measured at 60 ㎓.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.356-361
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• 2011

The flow characteristics of synthetic jet depending on rectangular and circular jet exit configuration are investigated using numerical computation with cross flow. In rectangular slot, synthetic jet generates the strong vortex, however, supply fewer momentum and effectiveness of flow control is reduced along flow direction. In circular slot, regular vortex is fanned from slot center to end and developed in flow direction. It affects the wider region than rectangular slot. The distribution of wall shear stress is considered in order to indicate the effectiveness of flow control device for flow separation delay. As a result, circular slot is a more suitable candidate for delaying flow separation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1049-1056
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• 2016

In this paper, a design method for a compact dual-band slot antenna with bent slot is studied. Bent slots are added on the rectangular slot of the proposed antenna for dual-band operation. The rectangular slot is fed by a coaxial cable by placing a rectangular feeding patch inside the slot. When the bent slots are added onto the both corner of the upper side of the rectangular slot symmetrically, a new resonant frequency is created in low frequency because of the increasement of the slot length. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 4.50-8.30 GHz band including 5GHz WLAN band is fabricated on an FR4 substrate with a dimension of 30 mm by 30 mm. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.40-2.49 GHz and 4.33-9.85 GHz for an input reflection coefficient < -10 dB.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2120-2125
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• 2015

In this paper, a rectangular waveguide probe with a ridge-loaded straight slot (RLSS) is presented for a near-field scanning microwave microscope (NSMM). The RLSS is located laterally at the end wall of the cavity and is loaded on double ridges in a narrow straight slot to improve the spatial resolution compared with a straight slot. The probe consists of a rectangular cavity with an RLSS and a feed section of a WR-90 rectangular waveguide. When the proposed NSMM is located at distance of 0.1mm in front of a substrate without patches or strips, the simulated full width at half maximum (FWHM) of the probe improve by approximately 31.5 % compared with that of a straight slot without ridges. One dimensional scanning of the E-plane on a sample under test was conducted, and the reflection coefficient of the near-field scanning probe is presented.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.57-64
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• 2017

In this paper, an asymmetric compact multiband slot antenna is proposed for global positioning system (GPS), worldwide interoperability for microwave access (WiMAX), and wireless area network (WLAN) applications. The top plane, a ground is composed of a rectangular slot with a trapezoidal-like stub, an inverted U-shaped slot at the right side of the rectangular slot, an inverted L-shaped slot at the left side of the rectangular slot, and three stubs. The proposed antenna is fed by an asymmetric cross-parasitic strip on the bottom plane. By properly designing the slots and stubs, four resonant frequency bands are achieved with -10 dB reflection coefficient bandwidths of 50 MHz, 400 MHz, 390 MHz, and 830 MHz in the 1.57 GHz GPS band, 2.4 GHz WLAN band, 3.5 GHz WiMAX band, and 5.5 GHz WLAN bands, respectively. The antenna has a total compact size of $13mm{\times}32mm{\times}0.8mm$. Simulated and measured results indicate that the proposed antenna has sufficient bandwidth and good radiation performance in each band.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.25-33
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• 2017

In this study, combustion tests were performed to investigate combustion performance of a pintle injector engine with double row rectangular slot which uses kerosene and liquid oxygens as propellants. The double row rectangular slot was designed to improve the combustion performance of a pintle engine with a single row and the blockage factor was changed from 0.7 to 1.0. The main design parameters of the double row were distance between rows, area ratio and aspect ratio. The characteristic velocity efficiency was measured from 92.4 to 96.9 percentage for double row but 86.8 percentage for single row. It showed the highest combustion performance at the BF 0.85.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.585-595
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• 2011

The flow characteristics of synthetic jet depending on rectangular and circular jet exit configuration are investigated using numerical computation with cross flow. In rectangular slot, synthetic jet generates the strong vortex but supplies fewer momentum and effectiveness of flow control is reduced along flow direction. In circular slot, regular vortex is formed from slot center to end. It affects the wider region than rectangular slot. The distribution of wall shear stress is considered in order to indicate the effectiveness of flow control device for flow separation delay. Consequently, circular slot is a more suitable candidate for delaying flow separation. In order to derive the optimal shape of a circular slot exit, hole gap and diameter that affect the flow structure and flow control were analyzed. As a result, consider the hole diameter and gap of circular slot exit design, effectiveness of the flow control can be increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2526-2533
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• 2015

In this paper, a design method for a compact dual-band coplanar waveguide-fed slot antenna using SRR(split-ring resonator) conductor is studied. The SRR conductor is loaded inside a rectangular slot of the proposed antenna for dual-band operation. When the SRR conductor is inserted into the slot, the original rectangular slot is divided into a rectangular loop region and a rectangular slot region, and frequency bands are created by the loop and slot, separately. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 3.40-5.35 GHz band is fabricated on an FR4 substrate with a dimension of 30 mm by 30 mm. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.38-2.51 GHz and 3.32-5.38 GHz for a voltage standing wave < 2, and measured gain is 1.7 dBi at 2.45 GHz, and it ranges 2.4-3.2 dBi in the second band.