• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.449-452
• /
• 2018

In this paper, we design a Wibro / WiFi dual band microstrip antenna for wireless broadband communication. The proposed antenna is designed to have the characteristics of FR-4 (er = 4.3), size of $40[mm]{\times}40[mm]$, and usable in 2.31[GHz] and 5.8[GHz] bands of Wibro / WiFi. The simulation is performed by CST Microwave Studio 2014 The simulation result shows that the gain is 2.308[dB] at 2.31[GHz] and 2.985[dB] at 5.8[GHz]. S-parameters were also found to be less than -10[dB] (WSWR2: 1) in the desired frequency band, and a small number of parameters and a compact antenna were designed. It is expected that many users will use the mobile communication antenna for accurate and fast communication for smooth wireless broadband communication.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.2
• /
• pp.100-105
• /
• 2006

In this paper, a low noise amplifier(LNA) in a receiver of a low noise block down converter (LNB) for direct broadcasting service(DBS) is implemented using GaAs HEMT. The LNA is designed for the bandwidth of 11.7 GHz-12.2 GHz. The two-stage LNA consists of a input matching circuit, a output matching circuit, DC-blocks and RF-chokes. Experimental results of the LNA show the noise figure less than 1.4 dB, the gain greater than 23 dB and the flatness of 1 dB in the bandwidth of 11.7 to 12.2 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.7
• /
• pp.631-638
• /
• 2009

In this paper, a wide-band monopole antenna for use in PCS/WDCMA/Wivro/S-DMB(1.750${\sim}$2.655 GHz) band is presented. The presented antenna is a trapezoidal monopole antenna which has back-side patch and improves the bandwidth. To confirm the wide-band characteristics and radiation pattern of presented antenna, the experimental antenna is fabricated and its radiation characteristics are measured, compared with calculated results. It is shown that the designed antenna has VSWR less than 1.5, gain over 2 dBi in 1.73${\sim}$3.48 GHz. The measured results show good agreement with calculated results. From the result, we confirm that the designed antenna can be used indoor antenna for PCS/WCDMA/WiBro/S-DMB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.1
• /
• pp.71-76
• /
• 2001

A Ka Band 3-stage MMIC (Monolithic Microwave Integrated Circuits) LNA (Low Noise Amplifiers) has been designed and fabricated far the Ka band satellite communications and BWLL(Broad Band Wireless Local Loop)system. The MMIC LNA consists of two single-ended type amplification stages and one balanced type amplification stage to satisfy noise figure, high gain and amplitude linearity. The 0.15${\mu}{\textrm}{m}$ pHEMT has been used to provide a ultra low noise figure and high gain amplification. Series and Shunt feedback circuits and λ/4 short lines were inserted to ensure high stability over the frequency range form DC to 80 GHz. The size of the MMIC LNA is 3.1mm$\times$2.4mm(7.44mm$^2$). The on wafer measured performance of the MMIC LNA, which agreed with the designed performance, showed the noise figure of less than 2.0 dB, and the gain of more than 26 dB, over frequency ranges from 22 GHz to 30 GHz.

• 한국정보통신설비학회:학술대회논문집
• /
• 2009.08a
• /
• pp.215-218
• /
• 2009

In this paper, Dual-band bandpass filter studied design using Parallel Coupled SIR(Stepped Impedance Resonator). This Dual-band bandpass filter design SIR of half-wavelength by Parallel-coupled type that is available to RFID system and Changed structure in Meander form by size reduce. Because seen Dual-band bandpass filter is designed so that is applicable for frequency 433MHz and 2.45GHz of RFID system is very wide distance between two pass-band, establish 433MHz by fundamental frequency and controlled 2.45GHz by 2st spurious resonance frequency bandstop filter of 1st spurious resonance frequency and Parallel coupled SIR Combine to remove 1st spurious resonance frequency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.5C
• /
• pp.506-511
• /
• 2002

In this paper, waveguide-based power combiner using conventional slotline-to-microstrip transition was proposed at Ka-band. The proposed 2-way and 4-way power combiner consist of waveguide-to-slotline transition, two or four slotline-to-microstrip transitions, and impedance matching networks. Their structures were simulated and optimized by 3-D FEM simulation. The 2-way power combiner showed a very low back-to-back insertion loss of 1.0 dB and return loss better than 15 dB from 25.7 GHz to 29.8 GHz except the resonant frequency. The 2-way power combining approach was extended to 4-way power combining using slotline tee junction. The 4-way power combiner showed the similar performance to that of 2-way power combiner with 2 GHz smaller bandwidth.

• ETRI Journal
• /
• v.46 no.2
• /
• pp.323-332
• /
• 2024

Receiver and transmitter monolithic microwave integrated circuit (MMIC) multifunction chips (MFCs) for active phased-array antennas for Ka-band satellite communication (SATCOM) terminals have been designed and fabricated using a 0.15-㎛ GaAs pseudomorphic high-electron mobility transistor (pHEMT) process. The MFCs consist of four-channel radio frequency (RF) paths and a 4:1 combiner. Each channel provides several functions such as signal amplification, 6-bit phase shifting, and 5-bit attenuation with a 44-bit serial-to-parallel converter (SPC). RF pads are implemented on the bottom side of the chip to remove the parasitic inductance induced by wire bonding. The area of the fabricated chips is 5.2 mm × 4.2 mm. The receiver chip exhibits a gain of 18 dB and a noise figure of 2.0 dB over a frequency range from 17 GHz to 21 GHz with a low direct current (DC) power of 0.36 W. The transmitter chip provides a gain of 20 dB and a 1-dB gain compression point (P1dB) of 18.4 dBm over a frequency range from 28 GHz to 31 GHz with a low DC power of 0.85 W. The P1dB can be increased to 20.6 dBm at a higher bias of +4.5 V.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.4
• /
• pp.1365-1368
• /
• 2014

A CPW-fed to CPS dipole antenna of triangular loop director by microstrip tapered balun is proposed for dual and wide band operations, in this paper. The proposed antenna is consisted of a CPW-fed to CPS transform, microstrip tapered balun element, CPS dipole driver and triangular loop director. A dual and wide bandwidth of the proposed dipole antenna is realized by introducing the triangular loop director and taper matching element. The operated frequency bandwidth is 1GHz (2.14~3.14 GHz) and 1.9 GHz (4.6~6.5 GHz) to return loss criterion of less than 10 dB. The measured return loss of the proposed antenna showed good results of the dual and wide band operating frequency and the radiation pattern. The proposed antenna is able to support WLAN wireless communications applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.4
• /
• pp.403-409
• /
• 2013

In this work, a CMOS two stage differential power amplifier which includes Marchand balun, transformer and injection-locked buffer is presented. The power amplifier is targeted for 70 GHz frequency band and fabricated using 65 nm technology. The measurement results show 8.5 dB maximum voltage gain at 71.3 GHz and 7.3 GHz 3 dB bandwidth. The measured maximum output power is 8.2 dBm, input $P_{1dB}$ is -2.8 dBm, output $P_{1dB}$ is 4.6 dBm and maximum power added efficiency is 4.9 %. The power amplifier consumes 102 mW DC power from 1.2 V supply voltage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.1
• /
• pp.42-49
• /
• 2018

In this paper, a dual-band microstrip-fed monopole antenna with a DGS(defected ground structure) for WLAN(wireless local area network) applications is presented. The antenna consists of a monopole and a defected ground, which were etched on both sides of the FR-4 substrate. The defected ground structure was used to obtain the dual band, while the step-by-step reduction in the monopole width was used to improve the impedance matching of the antenna. The antenna has an overall compact size of $44{\times}51{\times}1.6mm^3$, which was optimized by varying the size of the monopole and the ground plane such that it may resonate at the 2.4 GHz and 5 GHz bands of the WLAN. The measurement results showed that the antenna operates in the frequency band of 210 MHz(2.29~2.50 GHz) and 900 MHz(5.05~5.95 GHz) for a VSWR under 2, and showed omnidirectional radiation pattern at all desired frequencies.