• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.177-180
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• 2001

A decoupled, wide-band, perfectly magnetically conductor(PMC)-backed air waveguide antenna is designed and constructed for the use of the continuous electromagnetic wave ground penetrating radar in the frequency range from 200MHz to 600MHz. Two planar dipoles are located inside air slab covered by PMC on the top side and separated by an air gap from the bottom ground interface. The coupling between the transmitting and the receiving dipoles is calculated by less than -60dB over the frequency from 200MHz to 600MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1445-1454
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• 2008

In this paper, small UWB antenna with band-stop function for mobile handsets is proposed. A gap between radiator and under and side ground is adjusted for small size and broadband. A radiator is folded to the back side of PCB for miniaturization and tapered feeding structure is used to enhance matching characteristic. A antenna clearance has a size of $14{\times}14\;mm^2$ and a size of radiator is $10{\times}7\;mm^2$. It covers all UWB band from 3.15 GHz to 4.75 GHz and from 7.2 GHz to 10.2 GHz for VSWR<2 and has band stop characteristic at 5.8 GHz. A maximum gain is measured as 5.85 GHz. In case conventional handset case is considered, it also covers all UWB and a maximum gain is measured from -2 dBi to -2 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.5
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• pp.333-338
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• 2019

In this study, we introduce a dual-band ground radiation antenna using an endless metal-rim mode control method that operates in the WLAN band. In the proposed antenna, the metal-rim modes are excited as one- and two-wavelength-mode radiators by a dual-band ground radiation antenna, which occupies a small space on the ground plane. The metal rim surrounds the ground plane with a gap of only 2 mm. In addition, two capacitors are inserted between the ground plane and the endless metal rim to control the one- and two-wavelength modes of the endless metal rim. Based on simulation and measurement results, we noted that the proposed antenna has an impressively high radiation performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1067-1074
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• 2005

Studied antenna's basic structure was circular micro-strip patch antenna. Bandwidth was broaden and back-radiation pattern was decreased because studied antenna had PBG on a ground for improvement in its defect which is skin-effects. And character of antenna according to different shape of PBG was observed. Finally, air-gap whose dielectric constant is lower than substrates was added between substrates sc respond frequency was higher despite small size antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.41-46
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• 2003

In this paper, We designed the millimeter wave power amplifier employing PBG. The amplifier has the bandwidth from 24.6 GHz to 24.75 GHz. For improvement of the Linearity and the PAE of the amplifier, PBG was designed to suppress the 2nd harmonic of the Amplifer. The Proposed PBG have smaller area and better rejection characteristic than conventional PBG structure. The fabricated PBG shows 35 dB or more of rejection characteristic at the 2nd harmonic band of the amplifier. The amplifier has balanced structure having lange coupler which means better input$.$output return loss and higher output power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.9
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• pp.35-43
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• 2002

In this paper, microstrip ring with a narrow gap is characterized and used as a tunable microwave bandgap (MBG) structure. The center frequency of MBG is mainly determined by the mean circumference of the ring and coincides with odd mode resonance frequency of the ring resonator. The stop band formation by the proposed microstip MBG ring is due to the reflection of electromagnetic waves at the narrow gap introduced in the ring, and the reactive component mounted on the gap makes the stop band vary according to its value. The mounting of capacitor (inductor) is observed to decrease (increase) the center frequency of the stop band. The varactor-mounted microstrip MBG ring is expected to be useful in microwave switches and microwave amplifier circuits.

• Journal of electromagnetic engineering and science
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• v.13 no.2
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• pp.113-119
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• 2013

We developed a transformed, symmetrical, mushroom-like surface without via holes in cells focused on a 2.4-GHz WLAN band. Each slot in the novel type structure plays a key role in modeling at the desired frequencies. The designed artificial magnetic conductor (AMC) has several advantages, including a small size, a wider bandwidth, a short reflecting distance to the antenna, and easy fabrication because there are no via holes. Overall dimensions of the AMC cell are 21 mm $(Width){\times}21mm$ $(Height){\times}2.6mm$ (Thickness), and the bandwidth is about three times wider (11.7%) compared to that of a conventional AMC (4.0%). For evaluating the performance of the proposed structure, a reflector, which periodically consists of the designed AMC cells, was developed. The antenna with the investigated AMC reflector not only works within a quarter of the wavelength because of the extremely high wave impedance generated by the AMC cells on the surface of the structure but also reduces the specific absorption rate (SAR). Electromagnetic field (EMF) exposure to a human phantom was analyzed by applying the designed reflector to the 2.4-GHz dipole antenna in a tablet PC. The calculated peak SAR averaged over 1 g was 0.125 W/kg when the input power was 1 W and the antenna was located at 20 cm from the human phantom. However, the SAR value was only 0.002 W/kg (i.e., 98.4% blocked) when the designed reflector was inserted in front of the antenna.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.3-6
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• 2002

In this paper, Thin film bulk acoustic resonate.(TFBAR) fillers tuned by gold plated on-wafer inductors are presented. The air-gap type TEBAR is used with aluminum nitride(AIN) as piezoelectric material and platinum as top and bottom electrodes. Inductor equivalent model and modified Butterworth-Van Dyke(MBVD) model are employed for the frequency tuning of fabricated TFBAR bandpass filters. Fabricated inductor has inductance of 3 nH and Q factor of about 8 at 2 ㎓. It is clearly revealed that inductor tuning can enhance the bandwidth of ladder filters and improve out-of-band rejection characteristic around 10㏈.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.59-63
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• 2003

Modal properties of guided waves along circular dispersive double negative (DNG) index metamaterial rod waveguides are numerically investigated. Identical forms of dispersive dielectric and magnetic material constants are used for simplicity. For degenerated azimuthally symmetric mode, a multimode region, a single mode region, a band gap region and a forbidden region are found which cannot be observed in the case of the conventional dielectric rod waveguide. As the normalized frequency goes down, discrete guided modes are continuously generated, which is a reverse property of conventional dielectric rod waveguide. Also, there are high-frequency cutoffs, which have been generally examined in dispersive circular geometries such as a plasma column or a plasma Goubau line. In the single mode region, both the low- and high-frequency cutoffs are existed where the propagation constants are continued between the guided oscillating and surface modes.