• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.766-772
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• 2018

A 6~10 GHz wide-band power amplifier was designed using an InGaAs enhancement-mode(E-mode) $0.15{\mu}m$ pseudomorphic high-electron-mobility transistor(pHEMT). The positive gate bias of the E-mode pHEMT device removes the need for complex negative voltage generation circuits, therefore reducing the module size. The wire bond and substrate loss parameters were modeled and extracted using a three-dimensional electromagnetic(3D EM) simulation. For wideband characteristics, lossy matching was adopted and the gate bias was optimized for maximum power and efficiency. The measured gain, in/output return loss, output power, and power-added efficiency were greater than 20 dB, 8 dB, 27 dBm, and 35 %, respectively, in the 6~10 GHz band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.7-13
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• 2007

In this paper, we have designed and fabricated a small size wide-band monopole antenna which can integrate the frequency of previous business mobile communication system by adding 4 PCS of post type parasitic element on top-loaded sleeve monopole antenna. We have observed the properties of return loss upon a parameter change of element, and we also examined radiation properties in the band of PCS, W-CDMA, WiBro, W-LAN and S-DMB in order to make sure the suggested antenna's wide-band properties. We have found that the proposed antenna has omni-direction in horizontal plane and figure eight-direction in vertical plane, and we could have good return loss($Return\;loss{\leq}-10\;dB$) and $1.14{\sim}3.66\;dBi$ gain in $1.67{\sim}3.55\;GHz$ of frequency range($B/W{\fallingdotsep}72%$).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.133-136
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• 2003

UWB(Ultra-Wide Band) system is transmitted using Gaussian monocycle pulse of very short pulse duration less than 1 nsec. Therefore, transmission signal has ultra-wide band spectrum to GHz band of very low power and not interfere with the existing communication system. A collision of multipath waves in UWB system with tarrier frequency very different with general wireless communication system. In this paper, the BER(Bit Error Rate) performance of UWB system applying Binary Phase Shift Keying, Quadrature Phase Shift Keying, 16-Quadrature Amplitude Modulation method under multipath channel using computer simulation is compared and analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.345-350
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• 2005

An X-band push-push VCO for low cost applications is proposed. The designed push-push oscillator achieves a wide tuning range in the X-band by the collector bias tuning instead of extra varactor diodes. The measurement shows a wide tuning bandwidth of $900\;\cal{MHz}\;from\;10.9\;\cal{GHz}\;to\;11.8\;\cal{GHz}$ with a drain bias voltage varying from 4 to 9 V, excellent fudamental suppression of $-30\;\cal{dBc}$ and good phase noise of $-115\;\cal{dBc/Hz}\;@\;1\;\cal{MHz}$ offset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.704-709
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• 2007

In this paper, a CPW band-pass filter with a rejection band is proposed for UWB(Ultra-Wideband) communication systems. The proposed filter has a band-pass characteristic of wide-band by inserting only a slot in $50{\Omega}$ transmission line. To obtain the band-rejection function at WLAN frequency band($5.15{\sim}5.725GHz$), the designed filter is combined with folded slot resonators on the ground plane of the CPW structure. The fabricated CPW band-pass filter shows a compact size of $15.35{\times}13.60mm$, a wide passband of 2.8 GHz to 9.8 GHz and the narrow stop-band of 5.15 GHz to 5.71 GHz for 3-dB bandwidth. Also, the measured group delay is less than 400 psec throughout the operation frequency band except the rejection band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.467-478
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• 2019

This paper describes the development and measurement results of a wide-band planar active phase array antenna system for an electronic warfare jamming transmitter. The system is designed as an $8{\times}8$ triangular lattice array using a $45^{\circ}$ slant wide-band antenna. The 64-element transmission channel is composed of a wide-band gallium nitride(GaN) solid state power amplifier and a gallium arsenide(GaAs) multi-function core chip(MFC). Each GaAs MFC includes a true-time delay circuit to avoid a wide-band beam squint, a digital attenuator, and a GaAs drive amplifier to electronically steer the transmitted beam over a ${\pm}45^{\circ}$ azimuth angle and ${\pm}25^{\circ}$ elevation angle scan. Measurement of the transmitted beam pattern is conducted using a near-field measurement facility. The EIRP of the designed system, which is 9.8 dB more than the target EIRP performance(P), and the ${\pm}45^{\circ}$ azimuth and ${\pm}25^{\circ}$ elevation beam steering fulfill the desired specifications.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.249-254
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• 2005

This paper presents the design of a novel small and wide band planar inverted F-antenna which simultaneously covers GSM900/GPS/DCS1800/DCS1900/DMB service. The proposed antenna consisting of a main patch with rectangular slit, strip 1 and strip 2, occupied the total volume of.$15\times36\times6mm^3$. A very wide impedance bandwidth characteristic was achieved by optimizing both the distance between the feed line and short strip and the length of rectangular slit on the main patch. The commercial electromagnetic software, CST Microwave Studio, is used to design the structure. The maximum gains at the frequencies of 900, 1575, 1800, 1900, and 2600 MHz were 2.07, 1.07, 1.69 and 0.55, -1.99 dBi, respectively. The overall shape of the radiation patterns is suitable for mobile communication application.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.125-130
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• 2004

Various antennas have been developed to be used for UWB systems, However, Simultaneously meet omni-directional and low-VSWR requirements, essential for some applications such as UWB channel sounding. In this paper, we propose a novel wide band printed elliptic monopole antenna for UWB(Ultra wide Band). Wideband planar monopole disc antenna have been recently studied. The proposed antenna can cover m frequencies from 3.5GHz to 12GHz. it is determined from 10dB return loss. Antenna radiation pattern is omnidirectional at 3.5GHz - 10GHz. The antenna consists of the printed elliptical monopole disc with microstrip-line feed. Elliptic disc of antenna and ground height operate important to matching. The proposed antenna easy to construct UWB system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6C
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• pp.376-383
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• 2011

Since the first arrival path may not be the strongest path of UWB(Ultra Wide Band) multipath channels, this makes ToA(Time-of-Arrival) estimation becomes a challengeable issue. Furthermore, because of ultra bandwidth of received signals, the compressed sensing theory is employed to reduce the complexity caused by very high Nyquist sampling rate in coherent UWB receivers. In this paper, we propose a ToA estimation scheme which provides precise estimation performance, while exploiting the benefits of compressed sensing-based UWB receivers. Simulation results show that the proposed scheme can outperform other low complexity schemes in a wide range of signal-to-noise ratios.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.138-143
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• 2009

In this paper, a novel ultra-wide band filter which is operating at frequency bands from 3.1 GHz to 10.6 GHz is suggested. It is modified from the conventional ring filter and consisted of a ring with two parallel open-stub with length of ${\lambda}/8$. It improves the sharpness of the conventional ring filter and is compact. The measured results show that the fabricated filter has a insertion loss of 2.1 dB and the measured group delay of the filter is less than 463 ps through UWB frequency bands.