• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.245-252
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• 2016

In this paper, the design of a double-dipole quasi-Yagi antenna (DDQYA) with a gain over 7 dBi at 1.70-2.70 GHz band is studied. The proposed DDQYA consists of two strip dipoles with different lengths and a ground reflector, which are connected trough a coplanar stripline. The length of the second dipole is adjusted to increase the gain in the low frequency band, whereas a rectangular patch director is appended to the DDQYA to enhance the gain in the middle and high frequency band. The effects of the length of the second dipole, and the length and width of the director on the antenna performance are analyzed, and final design parameters to obtain a gain over 7 dBi 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 1.60-2.86 GHz for a VSWR < 2, and measured gain ranges 7.2-7.6 dBi at 1.70-2.70 GHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1021-1029
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• 2006

In this paper, we designed and implemented a dual wideband dipole type antenna for the reception of S-DMB (Satellite Digital Multimedia Broadcasting) and 2.4/5 GHz WLAN(Wireless Local Area Network) signals. The proposed antenna based on conventional monopole type dual band antenna was implemented as planar wideband dipole type antenna with the volume of $8{\times}33.8{\times}1.68mm^3$. The proposed antenna is printed type on FR4 substrate of 1.6 mm thick and composed of a dipole type antenna for low frequency band and two symmetric structured resonance elements for high frequency band. We confirmed antenna area with dense surface current for each frequency band with simulation. By varying the length of the antenna area with dense surface current, we could vary resonance frequency of each frequency band separately. Impedance bandwidths$(VSWR{\leq}2)$ are 362 MHz(14.23 %) for 2 GHz band and 1188 MHz(22.13, %) for 5 GHz band which show wideband characteristic. Measured maximum gains were 4.33 dBi for 2 GHz band and 5.48 dBi for 5 GHz band which showed improved performance. And the implemented antenna has a good omni-directional radiation pattern characteristic.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.4
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• pp.188-194
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• 2014

In this paper, an antenna which has quad band in LTE (0.746 ~ 0.798 GHz), GSM(0.824 ~ 0.960 GHz), DCS(1.71 ~ 1.88 GHz), WCDMA(1.91 ~ 2.17 GHz) is proposed. An antenna size is $122mm{\times}50mm{\times}0.8mm$ on FR4(${\epsilon}_r=4.4$) ground substrate. In the proposed antenna, branch line is applied to the conventional PIFA architecture to achieve multi-bandwidth. Coupling power supply is applied for a wide bandwidth. Result of the measurement is as follows. When the low frequency, the antenna presents gain of 0.93 ~ 1.92dBi, and radiation efficiency of 49.60 ~ 76.35 %, and When the high frequency, gain is 2.19 ~ 4.66dBi, and radiation efficiency is 60.40 ~ 80.01 %, and with a VSWR < 2 (${\leq}-10dB$)measurement results for standard satisfies all band. Judging from the result, proposed multiband antenna is expected to be applied. B4G mobile terminals since the antenna shows an outstanding performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.787-790
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• 2003

A 4-wavelength optical transceiver system is designed and implemented by using 4 OADMs (optical add-drop multiplexers), WDMs, and optical transceivers. In this new system, the wavelengths of 1510 nm and 1530 nm are used for upload and download signals, respectively, as well as the wavelengths of 1550 nm and 1310 nm which have been utilized in a 2-wavelength optical transceiver systems. The 4-wavelength optical module shows very encouraging pass characteristics of about - 5 dB and isolation characteristics of less than -40 dB, which is configured with two OADMs, 4 couplers, and WDM couplers by fusion splicing. Noise figure (NF) of the one-stage balanced amplifier designed and fabricated for receiver module is 0.38 dB and the amplifying gain is 14.2 dB. S$_{11}$, S$_{22}$ and input, output VSWR are -28.81 dB, -32.08 dB, 1.05 : 1, 1.08 : 1, respectively.y.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.5
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• pp.21-26
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• 2014

This paper proposes a frequency reconfigurable antenna which operates at not only LTE but also other currently serviced bands. The high band(1,710-2,170 MHz) performance was satisfied through PIFA structure, and the low band performance through the additional RF Switch by changing the state between SW1 and SW2. When the RF switch is SW1 state, the operation bandwidth is 782-907 MHz (GSM), and 738-861 MHz (LTE) at OFF state. The proposed antenna has a omni-directional radiation pattern and measured peak gains were 0.04-4.68 dBi at the SW1 state and 0.92-1.53 dBi at the SW2 state, respectively. Judging from the results, proposed reconfigurable antenna is expected to be applied to LTE-Advanced mobile terminals since the antenna shows an outstanding performance.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.4
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• pp.103-109
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• 1999

In this paper, we proposed to a new structure of T-shaped fed microstrip slot antenna using 2-layers dielectric material with a directional radiation characteristic. When the slot antenna of bi-directional radiation want to radiate only one direction, the reflector must be set up, but this antenna does'nt need set up reflector. T-shaped microstrip feed line is proposed for a better impedance matching to the microstrip slot antenna in a various range of slot widths. It was also found that the bandwidth of this antenna is proportional to the slot width. It was also found that the radiation resistance of this feed line structure is quite constant and low regardless to the slot width. We also analyzed this antenna by using the FDTD method, and calculating waves and electric field distribution in the time domain. we also are calculated return loss, VSWR, and radiation pattern in the frequency domain by Fourier transforming the time domain results, respectively. From the measured results, bandwidth was 34.8% in the center frequency. These results were in relatively good accordance with the calculated values.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.395-400
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• 2021

In this paper, the wideband patch antenna is simulated and manufactured for the wireless LAN of 5GHz band that is defined in IEEE 802.11a. In the 802.11a, 200 channels of 675MHz are defined. Therefore, the bandwidth is needed more than 12.3%. For the wideband characteristics, low dielectric constant is realized with the multi-layer of 2 teflon substrates and the air dielectric layer and the feeding method of the coupled-line is used. Optimized wideband patch antenna is simulated with the return loss of 38.99dB at the center frequency of 5.43GHz and the bandwidth of 12.9%. The gain of manufactured patch antenna is 4.38, 4.52, and 5.12dBi at the channel number of 46, 56, and 153, respectively.

• 전자공학회논문지 IE
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• v.45 no.1
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• pp.31-37
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• 2008

A Wibro RF down converter of 2.3GHz band is designed and implemented in this paper. The problems that can occur in the receiver LNA(Low Noise Amplifier) to minimize additional purposes. In addition, 2.3GHz band from the 75 MHz downward to minimize the losses in the process, transform and improve efficiency, and achieve stable characteristics can be used to make high frequency characteristics of the device. Wibro repeater uses a TDMA(Time Division Multiplexing Access) method is needed because the RF switch. Production criterion specification, the input voltage from +8 V 1.2A of current consumption, 60dB gain and the noise figure of less than 2.5dB, VSWR(Voltage Standing Wave Ratio) less than 1.5, more than IMD(Inter Modulation Distortion) 60dB satisfied. Environmental conditions ($-20^{\circ}C$ to $70^{\circ}C$) to pass the test of reliability in a long time, that seemed crafted Wibro down converter be applied to the Wibro repeater.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.442-448
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• 2018

In this paper, a microstrip antenna for LTE / LTE-A is designed and fabricated for a broadband mobile communication system. The proposed antenna is designed to have the characteristics of using FR-4 (er = 4.3), size of $40mm{\times}50mm$, and LTE / LTE-A frequency bands of 2.3 GHz and 2.5 GHz. 2014, and the simulation result shows that the gain is 2.391 dBi at 2.3 GHz and 2.566 dBi at 2.5 GHz. The S-parameter also showed a result of less than -10 dB (WSWR 2: 1) in the desired frequency band. The broadband mobile communication antenna has been miniaturized, high performance, and light weight, and an excellent and low cost system is continuously being developed, and a broadband mobile communication system is used by many people. Since LTE / LTE-A technology has been proposed according to the development of system and demand, it is expected that many users will design and manufacture antennas satisfying the above conditions and apply the applied technology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.517-531
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• 1999

This paper presents the development of the 2-mode variable gain high power amplifier for a transmitter of INMARSAT-M operating at L-band(1626.5-1646.5 MHz). This SSPA(Solid State Power Amplifier) is amplified 42 dBm in high power mode and 36 dBm in low power mode for INMARSAT-M. The allowable error sets +1 dBm of an upper limit and -2 dBm of a lower limit, respectively. To simplify the fabrication process, the whole system is designed by two parts composed of a driving amplifier and a high power amplifier, The HP's MGA-64135 and Motorola's MRF-6401 are used for driving amplifier, and the ERICSSON's PTE-10114 and PTF-10021 are used the high power amplifier. The SSPA was fabricated by the circuits of RF, temperature compensation and 2-mode gain control circuit in aluminum housing. The gain control method was proposed by controlling the voltage for the 2-mode. In addition, It has been experimentally verified that the gain is controlled for single tone signal as well as two tone signals. The realized SSPA has 42 dB and 36 dB for small signal gain within 20 MHz bandwidth, and the VSWR of input and output port is less than 1.5:1 The minimum value of the 1 dB compression point gets 5 dBm for 2-mode variable gain high power amplifier. A typical two tone intermodulation point has 32.5 dBc maximum which is single carrier backed off 3 dB from 1 dB compression point. The maximum output power of 43 dBm was achieved at the 1636.5 MHz. These results reveal a high power of 20 Watt, which was the design target.the design target.