• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.307-311
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• 2012

In this paper, a novel particle swarm optimization method based on IE3D is used to design a mobile communication Microstrip Patch Antenna. The aim of the thesis is to Design and fabricate an inset fed rectangular Microstrip Antenna and study the effect of antenna dimensions Length (L), Width (W) and substrate parameters relative Dielectric constant (${\varepsilon}r$), substrate thickness on Radiation parameters of Band width. When the antenna was designed, a dual-band, dual-polarized antenna was used to secure the bandwidth and improve performance, and a coaxial probe feeding method so that the phased array of antenna is easy.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.424-426
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• 2007

본 연구에서는 UHF 대역의 측정이 가능한 Cavity 안테나를 이용하여 절연진단기술에서의 적용가능성을 검토해 보았다. 제안된 안테나는 유전체 손실이나 급전라인의 손실이 없는 공기를 매질로 하므로, 고출력에 적합하며 고효율을 가진다. 또한 제작이 용이한 구조를 가지므로 대량 생산 시 많은 장점올 가질 것으로 기대된다. 시뮬레이션을 통하여 Cavity 안테나가 0.3 ${\sim}$ 10[GHz] 대역에서는 -10[dB]이하의 Return loss값을 가지는 측정주파수 대역이 약 2.7 ${\sim}$ 10[GHz]로 나타났으며, 0.3 ${\sim}$ 2.5[GHz]의 대역일 경우는 측정 주파수 대역이 약 0.7 ${\sim}$ 2.5[GHz]으로 나타남으로써 대표적인 전력기기인 GIS(Gas Insulated Switchgear : 가스절연개폐장치)에서 UHF 대역을 이용한 절연진단기술에서 사용하는 주파수 대역에서 사용이 가능함을 확인할 수 있었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.119-124
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• 2010

In this paper, microstrip antenna for Digital TV from 406 to 806 MHz has been designed and fabricated. In order to broaden the bandwidth of the antenna and improve of frequency properties, slot size, radius for capacitance controls were changed. DTV antenna was designed using HFSS simulation program and fabricated by FR4 substrate of dielectric constant 4.4.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.4
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• pp.363-372
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• 1997

We have developed the UHF CW/FM proximity sensor system. The UHF CW/FM Proximity Sensor is the system which recognizes the distance from the antenna to the target using the UHF band signal. To adjust sensing distance, we must change modulation frequency parameter or modulation index parameter. When we select the modulation frequency paramter for adjusting sensing distance, new modulation frequency generator and new band pass filter will be required. It is so inefficient that we choose modulation index parameters for adjusting sensing distance. In this paper, theoretical principles of the UHF CW/FM Proximity Sensor are analyzed and doppler signals for the distance from the antenna to the target are measured as the modulation index($\beta$) being changed. Three systems of which moduation indices are 38, 50, and 61 are made. We concluded that the sensing distance will decrease as the modulation index($\beta$) increases. It is in accord with the theory of this UHF CW/FM Proximity Sensor System.

• Food Science and Preservation
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• v.17 no.1
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• pp.79-83
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• 2010

The study was conducted to analyze the tag reading and box recognition performance of a gate-type RFID system using the UHF band to detect containers of red pepper. The reading rate of tags attached to container boxes was higher as tags were closer to antennas and the number of antennas was increased. Under optimal conditions, the reading rate was 100% and the range of distance from a carton to an antenna was 1-4 meters. When tags were attached to two sides of a box, the reading rate was lower when the tags were attached at the front and side. This was caused by data collision problems between tags. The reading rate of tags was 71.1-77.8% and the reading rate of red pepper boxes was 97.8-100.0% when the distance between the pallet under the boxes and four units of antennas was 5 meters or less, and when tags were attached at the front and side of boxes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.411-417
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• 2008

This paper presents the miniaturization of circularly polarized microstrip patch antenna for UHF-band RFID portable reader. The proposed antenna has a group of four I-slots on a conventional corner-truncated square microstrip patch and it is shown that the antenna size is reduced compared to the antenna without I-slots. A 76 mm by 76 mm small antenna with four I-slots is fabricated with 6.4 mm thick FR4 substrate and its 10 dB return loss bandwidth, the gain and the axial ratio are measured to be $938{\sim}975\;MHz$, $-0.88{\sim}-2\;dBi$, and $3.27{\sim}13.21\;dB$ within the 10 dB return loss bandwidth, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1114-1120
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• 2009

The conductivity of various electro-threads is analyzed, and the washable electro-thread embroidery UHF RFID tag antennas using the character shape without T-matching structure are designed by adding a T-matching structure. The RFID tag antenna using the electro-thread is easy to be embedded on a cloth as a wearable antenna because it is flexible and different from general copper inlay shape and tape type tag. The embroidery tag antennas are designed with the English alphabet 'F' and the Korea alphabet 'ㄹ' character. Those are easy to be applied to general clothes. The parameters of antennas are optimized and fabricated. The characteristics and the reading range patterns of the tag antennas are measured. The reading ranges of wet tags(tap water, sea water and soapy water) are tested and compared.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.174-182
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• 2009

In this paper, we propose a novel hybrid reader antenna using a triangular and rectangular sub-patch for near- and far-field RFID reader in UHF band. The antenna operates at 912 MHz, and the low-cost mass-production is available, since the antenna can be built by printing on a FR-4 substrate. The triangular patch is designed to produce a circularly polarized radiation along the bore-sight direction and the rectangular sub-patch is designed to generate a strong magnetic field over the antenna aperture. The measurement shows Hz field greater than -25 dBA/m(3 cm above the antenna aperture), and exhibits circularly polarized radiation(AR<3 dB) with a radiation gain of 6 dBi.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1468-1474
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• 2009

This paper shows an UHF RFID metallic tags using a Cavity structure for a long reading range. The reading range of a general passive tag is limited because the EIRP of a reader system is limited as 36㏈m by ISO 18000-6. To extend the reading range, the tag antenna should have a high gain antenna structure. The designed tag antenna is recognized over 10m range with a Cavity structure. The directivity pattern and the performance of the tag with the Cavity structure is stable when it is attached to a metallic object. The designed tag antenna has two kinds as cavity thickness. The sizes of designed tag antennas are $176\;{\times}\;52\;{\times}\;10\;mm$ and $176\;{\times}\;61\;{\times}\;30mm$ They can be attached to a large metallic materials and heavy equipments. The measured reading ranges of the tags are about 11m and 15m when they are attached to a metallic object.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.3
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• pp.159-166
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• 2018

Herein, a non-Foster matching circuit is designed to improve the impedance matching characteristics of small antennas in the VHF and UHF bands. The proposed non-Foster circuit is designed to operate with negative capacitance in a wide frequency band from 50 MHz to 1,000 MHz for use in various communication bands. To ensure the stability of the non-Foster circuit with conditional stability, the open-circuit stability condition of Linvill was satisfied, and the circuit was fabricated using the FR-4 substrate. The fabricated non-Foster circuit was combined with a small antenna to verify its performance by measuring the return loss and received power in the FM, DMB, and GSM bands. The measured return loss was improved from -6 dB to -30 dB, and the measured received power was improved from 0.5 dBm to 5.2 dBm.