• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.83-84
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• 2016

A wideband stacked patch antenna with parasitic elements, rectangular and triangle shaped patches, is proposed. Two different shaped parasitic elements are placed in the above of main rectangular microstrip patch antenna in order to achieve wide bandwidth for 860 MHz band. Coupling between the main patch and parasitic patches is realized by thick air gap. The gap and locations of parasitic patches are found to be the main factor of the wideband impedance matching. The proposed antenna is designed on a ground plane with small size of $119mm{\times}109mm$ for application of compact transceivers. And the impedance bandwidth of the antenna should satisfied CDMA band to the 780MHz~890MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.389-397
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• 2007

This paper proposes miniaturized broadband parasitic patch antenna. The proposed antenna consists of a probe fed reduced size main patch and U-shaped parasitic patches. The parasitic patches are incorporated to the radiating edges of the main patch to miniaturize the antenna size. The broadband impedance matching can be achieved by either E-plane or H-plane electromagnetic coupling between main patch and parasitic elements. The size of radiating elements is $18{\times}17.6\;mm^2$ and the overall dimension of designed antenna with substrate and ground plane is $25{\times}30{\times}4\;mm^3$. The fabricated antenna on a FR4 substrate shows two resonant frequencies(5.12 GHz and 6.08 GHz) with 27.3 %(1.5 GHz) fractional bandwidth at 5.5 GHz center frequency. The calculated and measured radiation patterns are almost similar to conventional patch antenna.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1855-1861
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• 2017

In this paper, the gain enhancement of an SDPA using a director and two parasitic patches is studied. The modified balun is used to increase the bandwidth, whereas the director and two parasitic patches are appended to the SDPA to enhance the gain in the middle and high frequency bands. The effects of the distance between the director and parasitic patches on the antenna performance are analyzed, and the SDPA with a gain over 7 dBi at 1.54-2.99 GHz band is designed. The proposed SDPA is fabricated on an FR4 substrate with a dimension of $90mm(L){\times}135mm(W)$ in order to validate its performance. The fabricated antenna shows a frequency band of 1.56-3.10 GHz for a VSWR < 2, and it is confirmed by measurement that gain maintains over 7 dBi in the frequency range of 1.54-3.00 GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.874-879
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• 2016

A wideband stacked patch antenna with parasitic elements, rectangular and triangle shaped patches, is proposed. Two different shaped parasitic elements are placed in the above of main rectangular microstrip patch antenna in order to achieve wide bandwidth for 860 MHz band. Coupling between the main patch and parasitic patches is realized by thick air gap. The gap and locations of parasitic patches are found to be the main factor of the wideband impedance matching. The proposed antenna is designed and fabricated on a ground plane with small size of $119mm{\times}109mm$ for application of compact transceivers. The fabricated antenna on an FR4 substrate shows that the minimum measured return loss is below -11.68dB at 824 MHz and an impedance band of 818~919 MHz(11.7%) at 10dB return loss level. The measured radiation patterns are similar to those of a conventional patch antenna with maximum gain of 2.11 dBi at 824 MHz.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.59-60
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• 2017

In this paper, the bandwidth and gain enhancement of a series-fed dipole pair antenna (SDPA) using a modified balun., a director, and two parasitic patches is studied. The proposed SDPA consists of two strip dipoles with different lengths, a ground reflector, which are connected through a coplanar strip line, a director, and two parasitic patches. The modified balun is used to increase the bandwidth, whereas the director and two parasitic patches are appended to the SDPA to enhance the gain in the middle and high frequency band. A prototype of the proposed SDPA is fabricated on an FR4 substrate, and the experimental results show that the antenna has a frequency band of 1.56-3.10 GHz for a VSWR < 2, and measured gain maintains over 7 dBi in the frequency range of 1.55-3.00 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.428-434
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• 2009

In this paper, we propose an U-slot microstrip antenna with the U-shaped parasitic patches. U-slot and parasitic patches make two resonant frequencies and one additional resonant frequency, respectively, so that the impedance band-width of the antenna is expanded. The size of radiator part is $64{\times}53\;mm^2$ and the entire size of the antenna is $150{\times}150{\times}11.5\;mm^3$. The measured bandwidth is $1.85{\sim}2.40\;GHz$. Thus, our antenna can be used for DCS1900, WCDMA and WiMax services. The radiation characteristic is almost same in the bandwidth, the beam width is about $60^{\circ}$, and the gain is more than 7 dBi.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.387-390
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• 2005

A survey was conducted during February-March 2003 to determine the occurrence and population density of plant-parasitic nematodes in strawberry (Fragaria ananassa) fields, cultivated under plastic houses in major strawberry growing regions of Gyeongbuk and Chonbuk provinces, Korea. The survey revealed presence of eleven species of plant-parasitic nematodes viz., Aphelenchoides fragariae, Criconemoides morgensis, Ditylenchus dipsaci, Helicotylenchus dihystera, Hirschmanniella imamuri, Meloidogyne arenaria, M. incognita, Pratylenchus penetrans, Psilenchus hilarulus, Tylenchorhynchus claytoni and Xiphinema sp. Frequency and density of each species were highly variable from field to field and within the field. Plant growth was not uniform in the surveyed fields under plastic houses; stunted growth, chlorotic leaves, small curled or crinkled leaves, deformed buds and flowers and wilted plants with fewer fruits were observed in patches.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.293-296
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• 2002

In this paper, we proposed a beam tilting microstrip patch array antenna for the reception of satellite signals by using low cost copper etched polyester films and foams. The configuration and coupling mechanism of the proposed antenna are similar to the dipole Yagi-Uda antenna. It is composed of 3 layers of polyester films and three layers of foam. In order to prevent unwanted radiation and coupling loss by microstrip feeding networks and parasitic patches, a stacked layer with rectangular slots above the driver patch array is inserted. The 16${\times}$8 element microstrip Patch way antenna is Presented by experimental results. Its beam patterns are affected by many parameters such as sizes of the patches, gap between the patches. characteristics of the substrates, feeding method, etc. Owing to its complexities of various design parameters, both simulation and experiment were performed. The fabricated antenna received DBS signal from KOREASAT 3 by doing nothing but adjusting azimuth direction.

• Korean Journal of Medicinal Crop Science
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• v.12 no.5
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• pp.355-359
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• 2004

A survey was conducted during $April{\sim}May$ 2004 to determine the occurrence and population density of plant-parasitic nematodes in ginseng (Panax ginseng C.A. Meyer) growing fields, in major ginseng growing regions of Chungbuk, Chungnam, Gyeongbuk and Kyongki provinces. The survey revealed presence of eleven species of plant-parasitic nematodes namely, Criconemoides morgensis, Ditylenchus destructor, Helicotylenchus dihystera, Meloidogyne incognita, M. hapla, Paratylencgus lepidus, Pratylenchus penetrans, Psilenchus hilarulus, Trichodorus similis, Tylenchorhynchus claytoni and Xiphinema americanum. Frequency and density of each species were highly variable. M. incognita and M. hapla were the predominant species, their infestation observed in 46.3 and 39.4% fields with an average density of $78{\sim}254\;and\;76{\sim}211$ nematodes per $300\;cm^3$ soil, respectively. Whereas, T. similis and X. americanum were rarely observed; only in 2.3 and 1.8% of surveyed fields and their density was $10{\sim}17\;and\;7{\sim}10$ individuals per $300\;cm^3$ soil, respectively. They are recorded herewith for the first time from ginseng fields of Korea. In nematode-infestated fields, stunted plant growth with chlorotic leaves, and wilted plants were observed in patches.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.9
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• pp.1642-1648
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• 2017

Ultra-wideband antennas are desired for several applications including satellite communications, radars, remote sensing system, telescopes, and microwave imaging systems. There are many types of wideband antenna structures, but the tapered slot Vivaldi antenna is advantageous in terms of cost, weight, scan angle capabilities, end-fire radiation, and ease of feeding and system integration. In this paper, a modified antipodal Vivaldi antenna is presented. A novel AVA with H-shaped parasitic patches has the capacity to improve the radiation characteristics in the whole operation frequencies. A prototype of the modified antenna with RT/duroid 5880 substrate of a relative dielectric constant (${\epsilon}_r$) of 2.2, and a thickness of 31mil is fabricated and experimentally studied as well. It measures a ${\mid}S_{11}{\mid}$ of less than -10dB and gain of 9-12dBi over 7.8-52.5GHz which shows reasonable agreement with the simulated one.