• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.35-43
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• 2016

A compact ultra-wide band antenna with a quadruple band-notched characteristic is proposed. The proposed antenna consists of a slotted trapezoid patch radiator, an inverted U-shaped band stop filter, a pair of C-shaped band stop filters, and a rectangular ground plane. To realize the quadruple notch-band characteristic, a U-shaped slot, a complementary split ring resonator, an inverted U-shaped band stop filter, and two C-shaped band stop filters are utilized in this antenna. The antenna satisfies the -10 dB reflection coefficient bandwidth requirement in the frequency band of 2.88-12.67 GHz, with a band-rejection characteristic in the WiMAX (3.43-3.85 GHz), WLAN (5.26-6.01 GHz), X-band satellite communication (7.05-7.68 GHz), and ITU 8 GHz (8.08-8.87 GHz) signal bands. In addition, the proposed antenna has a compact volume of $30mm{\times}33.5mm{\times}0.8mm$ while maintaining omnidirectional patterns in the H-plane. The experimental and simulated results of the proposed antenna are shown to be in good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.924-929
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• 2009

In this paper, a dual-band MIMO antenna with a band stop matching circuit for next generation USB dongle application is proposed. The proposed multiband MIMO antenna consists of two dual-band PIFAs which provide wideband characteristics. In order to improve the isolation characteristic at the LTE(Long Term Evolution) band, a band stop matching circuit was inserted at the corner of each antenna element. The inserted band stop matching circuit is to suppress the surface current at the specific frequency band and to generate two additional resonances around 770 MHz for LTE band and near 830 MHz for digital communications network(DCN) service. The proposed MIMO antenna can cover LTE and DCN services, simultaneously.

• ETRI Journal
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• v.30 no.5
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• pp.735-737
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• 2008

We propose a novel spatial multi-band-stop filter using modified multiple loop array elements to block electromagnetic waves or signals of mobile phones in public facilities. It operates at the following frequency bands: Korean cellular (824 MHz to 894 MHz), Personal Communication Service (PCS) (1.75 GHz to 1.87 GHz), and IMT-2000 (1.92 GHz to 2.17 GHz). Two frequency selective surfaces with modified multiple-loop elements are printed on the top and bottom of a pair-glass pane, which is a pair of glass panes with an air gap between them. A modified multiple-loop element with a meander line is used to make the size of the filter compact. The simulated and measured results show good agreement, which confirms the usefulness of the proposed tri-band spatial filter.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.33-38
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• 2013

In this paper, we present the design and measured performances of an dual-band Gysel power divider based on band-stop characteristic. After the Gysel divider is designed by lumped elements at single operating frequency, and then using filter conversion technique the lumped elements were changed a band-stop characteristic with dual-band characteristics. The features of this design method are that ${\lambda}/4$ transmission line by replacing lumped elements suppressed harmonic characteristics and also can reduce the size. To validate of the proposed power divider, the divider has been designed and measured at 880 MHz and 1650 MHz dual frequencies. The measured performances of the Gysel divider agree with prediction results at two frequencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1065-1072
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• 2012

In this paper, the method of design of the waveguide band-pass filter and limiter in radar system is proposed. First, we design a self-resonant iris, which can behave as a band-pass filter by mounting the PIN diode on the iris. When low power microwave is incident on the proposed element, the element behaves as a band-pass filter. Under a high power microwave condition, however, the element behaves as a limiter having wide band stop characteristics. The fabricated element has a pass band with -0.7 dB insertion loss at 10 GHz under the low power condition and isolation about 25 dB under the high power condition.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.35-38
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• 2003

In this paper, compact lumped-element low-pass filter structure with two transmission zeros at second and third harmonics is presented. The use of lumped-elements and transmission zeros can provide the advantages of compact size, sharp cutoff and wide stop-band frequency response. The proposed low-pass filter is a modified Chebyshev low-pass filter type and is implemented by the use of low temperature co-fired ceramic (LTCC) technology. This filter has been verified by both simulation and experiment. The simulated and experimental results agree very well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.887-894
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• 2007

In this paper, design and fabrication of the LPF with controllable four transmission zeros using electric coupling and added open stub is presented. Pass-band of the LPF is GSM band, and two transmission zeros are generated by the electric coupling at the WiBro and S-DMB band, And the other two transmission zeros are generated by the open stub at the upper frequencies. Harmonic frequency of the stop-band is suppressed by the realization of the filter using quasi-lumped element with small parasitic values. $C_M$, which is the electric coupling element of the equivalent circuit, is realized by the distance control between the open stubs of the filter structure. The fabricated LPF used teflon substrate with relative permittivity of 2.6. And it has a size of $38{\times}20{\times}0.79 mm^3$, which is including a feed line. The measured 3 dB cut-off frequency is 1.55 GHz, and locations of the transmission zeros are 2.20, 2.43, 4.11 and 6.84 GHz, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1237-1242
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• 2016

In this paper, the low pass filter with harmonics suppression and rejection using parallel coupled-line and radial type open stub is presented. And the resultant characteristic of the proposed low pass filter is that the harmonics are suppressed and rejected in wide bandwidth due to the parallel coupled-line structure. The open stub of a low pass filter is constructed in radial type which can be used to adjust the size of filter. The size of the proposed low pass filter is $6.98{\times}7.60mm2$ and the cut off frequency is 2.45 GHz. And the filter is economical in unit cost and can be constructed easily and has the merit of mass product because the filter is composed of distributed element. Also, the widely rejected harmonics is 128 % in the bandwidth and the insertion and return losses of the low pass filter are 1.07 dB and 19.5 dB, respectively.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.39.2-39.2
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• 2010

In this paper, I present the domestic development of near infrared camera systems for the ground telescope and the space satellite. These systems are the first infrared instruments made for astronomical observation in Korea. KASINICS (KASI Near Infrared Camera System) was developed to be installed on the 1.8m telescope of the Bohyunsan Optical Astronomy Observatory (BOAO) in Korea. KASINICS is equipped with a $512{\times}512$ InSb array enable L band observations as well as J, H, and Ks bands. The field-of-view of the array is $3.3'{\times}3.3'$ with a resolution of 0.39"/pixel. It employs an Offner relay optical system providing a cold stop to eliminate thermal background emission from the telescope structures. From the test observation, limiting magnitudes are J=17.6, H=17.5, Ks=16.1 and L(narrow)=10.0 mag at a signal-to-noise ratio of 10 in an integration time of 100 s. MIRIS (Multi-purpose InfraRed Imaging System) is the main payload of the STSAT-3 in Korea. MIRIS Space Observation Camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}{\times}3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI of 30 layers, and GFRP pipe support in the system. Opto-mechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform the Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.11-19
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• 2013

In this paper, we designed and implemented the planar monopole antenna using the coupling effect for the multi-band characteristic. A parasitic element for the multi-band characteristic based on a rectangular patch with single resonance is inserted. Spiral shaped parasitic element is used for minimizing the antenna size and obtaining the multi-resonance characteristic. The frequency characteristics are modified and optimized by varying specific parameters. By inserting an L-shaped resonator at both sides of the feed line which connected through the via hole to the ground plane, unnecessary frequency bands are eliminated. Proposed antenna dimension is $40{\times}60{\times}1mm^3$. It is fabricated on the FR-4 substrate(${\varepsilon}_r$=4.4) using a microstrip line of $50{\Omega}$ for impedance matching. By measurement results, the characteristic of the return loss under -10 dB are 1.714~2.496 GHz, 2.977~4.301 GHz, and 4.721~6.315 GHz, and the radiation patterns have omni-directional shapes.