• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.56-58
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• 2013

In this paper, a design method to obtain a band rejection characteristic in the 2.4-2.484 GHz WLAN band is studied for a series-fed dipole pair (SDP) antenna operating in the band of 1.7-2.7 GHz for mobile communication base station applications. The band rejection characteristic is achieved by inserting U-shaped slots on the coplanar strip line connecting the two dipole elements of the SDP antenna. The effects of the location and dimension of the slots on the band rejection characteristics are examined. The optimized SDP antenna with WLAN band rejection is fabricated on an FR4 substrate and the experimental results show that the antenna has a desired band rejection performance with a frequency band of 1.65-2.78 GHz (51.0%) for a VSWR < 2, and a rejection band of 2.39-2.54 GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1982-1987
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• 2013

In this paper, a design method to obtain a band rejection characteristic in the 2.4-2.484 GHz WLAN band is studied for a series-fed dipole pair (SDP) antenna operating in the band of 1.7-2.7 GHz for mobile communication base station applications. The band rejection characteristic is achieved by inserting U-shaped slots on the coplanar strip line connecting the two dipole elements of the SDP antenna. The effects of the location and dimension of the slots on the rejection band characteristics are examined. The optimized SDP antenna with WLAN band rejection is fabricated on an FR4 substrate and the experimental results show that the antenna has a desired band rejection performance with a frequency band of 1.65-2.78 GHz (51.0%) for a VSWR < 2, and a rejection band of 2.39-2.54 GHz.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.169-174
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• 2018

In this paper, a design method for a wideband LPF for harmonic suppression applications is investigated. The proposed wideband LPF is comprised of four circular slot pairs with different diameters, which are added symmetrically in the ground plane of a CPW transmission line. Four circular slot pairs act as a defected ground structure and provide a wideband low pass characteristic. The circular slot with the smallest diameter is located at the side of port 1, and the diameter of the circular slot is increased as it goes toward port 2. The low pass characteristics of each circular slot are compared with the proposed wideband LPF. The final designed LPF was fabricated on FR4 substrate, and its characteristics were tested. The measured S11 characteristic was maintained at over -3.3 dB in the frequency range of 1.89-20.00 GHz band, whereas the S21 characteristic was less than -21.4 dB in the frequency range of 2.66-20.00 GHz.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.4
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• pp.61-71
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• 1999

The recent trend toward higher frequencies, miniaturization and lower-cost in wireless communication equipment is demanding high density packaging technologies such flip chip interconnection and multichip module(MCM) as a substitute of conventional plastic package. With analyzing the recently reported research results of the RF flip chip, this paper presents the technical issues and advantages of RF flip chip and suggest the flip chip technologies suitable for the development stage. At first, most of RF flip chips are designed in a coplanar waveguide line instead of microstrip in order to achieve better electrical performance and to avoid the interaction with a substrate. Secondly, eliminating wafer back-side grinding, via formation, and back-side metallization enables the manufacturing cost to be reduced. Finally, the electrical performance of flip chip bonding is much better than that of plastic package and the flip chip interconnection is more suitable for Transmit/Receiver modules at higher frequency. However, the characterization of CPW designed RF flip chip must be thoroughly studied and the Au stud bump bonding shall be suggested at the earlier stage of RF flip chip development.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.252-258
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• 2017

In this paper, the bandwidth and gain enhancement of a double-dipole quasi-Yagi antenna (DDQYA) using a modified balun and two directors is studied. The proposed DDQYA consists of two strip dipoles with different lengths, a ground reflector, which are connected through a coplanar strip line, and two directors. The modified balun is used to increase the bandwidth, whereas two directors are appended to the DDQYA to enhance the gain in the middle and high frequency band. The effects of the length and width of the first director on the antenna performance are analyzed, and final design parameters to obtain a gain over 7 dBi at 1.60-2.90 GHz band are obtained. A prototype of the proposed DDQYA is fabricated on an FR4 substrate, and the experimental results show that the antenna has a frequency band of 1.57-3.00 GHz for a VSWR < 2, and measured gain ranges 7.1-7.8 dBi at 1.60-2.90 GHz band.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4165-4170
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• 2012

In this paper, a method for the improvement in the gain and bandwidth of a microstrip-fed broadband planar quasi-Yagi antenna (QYA) is studied. The broadband characteristics of the QYA are achieved from the coplanar strip-fed planar dipole driver and a parasitic director close to the driver. In order to obtain stable gain variation over the required frequency band, a director and a ground reflector are appended to the driver having a nearby parasitic director. The QYA is fed through an integrated balun composed of a microstrip line and a slot line which are terminated in a short circuit. By adjusting the feeding point, a broadband impedance matching is obtained. A QYA with an operating frequency band of 1.75-2.7 GHz and a gain > 4.5 dBi is designed and fabricated on an FR4 substrate with dielectric constant of 4.4 and thickness of 1.6mm. The experimental results show that the fabricated antenna has good performance such as a broad bandwidth of 59.7%(1.55-2.87 GHz), a stable gain between 4.7-6.5 dBi, and a front-to-back ratio > 10 dB. The measured data agree well with the simulation, which validates this study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.691-699
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• 2012

In this paper, we present a Vt-DRO with a low phase noise, which is achieved by improving the coupling structure between the dielectric resonator and microstrip line. The Vt-DRO is a closed-loop type and is composed of 3 blocks; dielectric resonator, phase shifter, and amplifier. We propose a mathematical estimation method of phase noise, using the group delay of the resonator. By modifying the coupling structure between the dielectric resonator and microstrip line, we achieved a group delay of 53 nsec. For convenience of measurement, wafer probes were inserted at each stage to measure the S-parameters of each block. The measured S-parameter of the Vt-DRO satisfies the open-loop oscillation condition. The Vt-DRO was implemented by connecting the input and output of the designed open-loop to form a closed-loop. As a result, the phase noise of the Vt-DRO was measured as -132.7 dBc/Hz(@ 100 kHz offset frequency), which approximates the predicted result at the center frequency of 5.3 GHz. The tuning-range of the Vt-DRO is about 5 MHz for tuning voltage of 0~10 V and the power is 4.5 dBm. PFTN-FOM is -31 dBm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1908-1914
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• 2013

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) reception. The coplanar strip line which feeds the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type rectangular director at a location close to the driver dipole, broadband impedance matching and gain enhancement in a high frequency region are obtained. The gain characteristics in a low frequency region are improved by adding a reflector formed by a truncated ground plane. To reduce the antenna size, the strip-type dipole and reflector are modified to half bow-tie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as a design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV. The optimized antenna is fabricated on an FR4 substrate and the experimental results show that the antenna has a good performance such as a frequency band of 450-848 MHz for a VSWR < 2, gain > 4.1 dBi, and front-to-back ratio > 10.4 dB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5214-5218
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• 2011

In this paper, bandwidth improvement of a series-fed two dipole array(STDA) antenna applicable for mobile communication base station antennas is studied. The proposed STDA antenna consists of two strip dipole antennas with different lengths which are connected directly trough a coplanar stripline(CPS). By adjusting the spacing between the two dipoles and the length of the second dipole, the bandwidth of the STDA can be enhanced. In addition, an integrated balun composed of a short-circuited microstrip line and a slot line is utilized to minimize the area required for a feeding part, and a broadband impedance matching is obtained by adjusting the feeding point. Based on the proposed antenna structure, an STDA antenna covering the frequency band ranging from 1.75 GHz to 2.7 GHz, which includes almost all the existing mobile communication frequency bands, with more than 5 dBi gain is designed and fabricated on an FR4 substrate with dielectric constant of 4.4 and thickness of 1.6mm, and experimentally tested. The fabricated antenna shows impedance bandwidth of 49%(1.7-2.8 GHz) for VSWR<2, a gain higher than 5.5 dBi, and a front-back ratio better than 12 dB.