• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.124-128
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• 2009

This raper proposes a dual-bandstop filter, which is based on a metamaterial transmission line using the composite right/left-handed (CRLH) and dual composite right/left-handed (D-CRLH) structures. The metamaterial structure is used for miniaturization and dual-bandstop operation at the TDMB frequency range (195 MHz) and DVB-T/H frequency range (670 MHz). The size of the proposed filter is $30{\times}15\;mm$, and the -10 dB bandstop fractional bandwidth is approximately 73 % and 50 % at each frequency, respectively.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.5 no.1
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• pp.43-59
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• 2006

A compact and broadband $4\times1$ array antenna was developed for 3G smart antenna system testbed. The $4\times1$ uniform linear away antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% $(VSWR\leq1.5)$, 21.78% $(VSWR\leq2)$ with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.41-58
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• 2007

A compact and broadband $4{\times}1$ array antenna was developed for 3G smart antenna system testbed. The $4{\times}1$ uniform linear array antenna was designed to operate at 1.885 to 2.2GHz with a total bandwidth of 315MHz. The array elements were based on the novel broadband L-probe fed inverted hybrid E-H (LIEH) shaped microstrip patch, which offers 22% size reduction to the conventional rectangular microstrip patch antenna. For steering the antenna beam, a commercial variable attenuator (KAT1D04SA002), a variable phase shifter (KPH350SC00) with four units each, and the corporate 4-ways Wilkinson power divider which was fabricated in-house were integrated to form the beamforming feed network. The developed antenna has an impedance bandwidth of 17.32% ($VSWR{\leq}1.5$), 21.78% ($VSWR{\leq}2$) with respect to center frequency 2.02GHz and with an achievable gain of 11.9dBi. The design antenna offer a broadband, compact and mobile solution for a 3G smart antenna testbed to fully characterized the IMT-2000 radio specifications and system performances.

• Journal of IKEEE
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• v.24 no.2
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• pp.446-452
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• 2020

In this paper, we propose a energy-saving LED module using K-band microwave motion detecting sensor. To oscillate K-band microwave signal, An oscillator using a hairpin-type microstrip resonator was designed to increase stability and make fabrication easier. To radiate the microwave signal, a two-channel(TX/RX) patch antenna arrays was developed. Wilkinson power divider and ring hybrid mixer were developed and applied to obtain Doppler shift from the received signal. Shield cans were installed to protect the stability of the signals and unwanted external noise. The proposed motion detection sensor was mounted on a demonstration LED module and the energy saving performance through pre-test was verified.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.828-834
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• 2023

In this paper, we studied an antenna that forms a wide beam width by applying a horn-shaped reflector to a patch array antenna. To implement a wide beam width, three patches were arranged in each of the four directions on a square microstrip substrate, and a horn-shaped reflector was applied to the rear of the array antenna. Through this structure, the vertical beam pattern formed from the patch was converted to a diagonal direction, and as a result, the beam widths formed in each of the four sectors were added to create a wide beam width close to a hemisphere. The proposed antenna was studied for application to UAV(unmanned aerial vehicle), and the simulation test results confirmed that the 4.5 dBi beam width was 146.8°.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.896-905
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• 2004

In this paper, the design, fabrication and experiment on a planar array antenna with a flat-topped radiation pattern for a mobile base station antenna were described. The current distribution of an antenna aperture, which is easily realizable in a feeding network compared with the conventional one of sin(x)/x was optimized for shaping a desired flat-topped radiation pattern. The planar array antenna designed in this paper has a rectangular lattice and is composed of array elements of 16${\times}$8. Each radiating element, which is a microstrip element fed coaxially, has a linear vertical polarization and the feed network which use a Wilkinson power divider and a 180$^{\circ}$ ring hybrid coupler as a base element is designed. The flat-topped radiation pattern with 90$^{\circ}$ is shaped by 16 array elements with the element spacing of 0.55 λ$_{ο}$ in the azimuth plane, and the normal radiation pattern with 10$^{\circ}$ is shaped by 8 array elements with the element spacing of 0.65 λ$_{ο}$ in the elevation plane. Also, the planar array antenna is symmetrically divided into four parts. It consists of one hundred-twenty-eight radiating elements, thirty-two 1-4 column dividers, low 1-8 row dividers and one 1-4 input power divider. In order to verify electrical performances of the planar way antenna proposed in this paper, the experimental breadboard operated in tile band of 1.92～2.17 GHz(IMT2000 band) was fabricated, and its experimental results were a good agreement with simulation ones.

• Journal of Advanced Navigation Technology
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• v.15 no.1
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• pp.97-103
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• 2011

This paper presents a dual-band balanced mixer using nonlinear phase characteristic of composite right/left-handed (CRLH) transmission line. This metamaterial structure provides low LO leakage and high RF to LO isolation without additional filters for LO and RF path. The balanced mixer consists of balun and Wilkinson divider with dual-band characteristic of unit-cell which behaves like a CRLH metamaterial. Experimental results are used to verify the proposed metamaterial functions. The balanced mixer design results in an operating frequency of 870 MHz and 1660 MHz with an optimum mixer conversion loss of 15.2 dB at 870 MHz and 21.2 dB at 1660 MHz.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.66-71
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• 2017

This paper describes implementation of a 165 MHz, 5 kW RF high power amplifier (HPA) for particle accelerator applications. The HPA consists of a drive amplifier for main amplifiers driving, sixteen 600 W class-AB push-pull power amplifier pallets and Wilkinson power divider/combiner using lumped LC components, which are divided/combined power amplifier pallet outputs. To detected the amplifier circuit of normal and reflected output power conditions, we used a bidirectional coupler. To radiate heat of main power amplifier, we were used an water-cooled copper plates to go through a water for radiation of heat. The HPA of center frequency 165 MHz has archived an efficiency of 62.5 % at 5 kW of power level experimentally.