• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.18-23
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• 2006

In this paper, we demonstrate a fully integrated X-band image rejection down converter, which was developed using InGaP/GaAs HBT MMIC technology, consists of two single-balanced mixers, a differential buffer amplifier, a differential YCO, an LO quadratue generator, a three-stage polyphase filter, and a differential intermediate frequency(IF) amplifier. The X-band image rejection downconverter yields an image rejection ratio of over 25 dB, a conversion gain of over 2.5 dB, and an output-referred 1-dB compression power$(P_{1dB,OUT})$ of - 10 dBm. This downconverter achieves broadband image rejection characteristics over a frequency range of 1.1 GHz with a current consumption of 60 mA from a 3-V supply.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.8
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• pp.970-974
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• 2007

A mixer is a key component in the wireless communication systems. In this paper, we design a mixer which is used in a frequency modulated continuous wave(FMCW) radar system. The frequency sweep range of the radar is from 10 GHz to 11 GHz. The transmitted and received signals of the FMCW radar are applied to LO and RF ports of the mixer, respectively, but the frequency difference between the two signals, which is called "a beat frequency" is under a few KHz and depending on the distance to target. Thus the isolation between the LO and RF ports is very important factor to design this mixer. In this paper we propose a single balanced resistive mixer using GaAs MESFET for this application. We first design a single-ended type resistive mixer using a simulation tool, then design a balanced type to increase the LO-to-RF isolation of the mixer. We fabricated the mixer on the substrate of dielectric constant 10 and thickness 0.635 mm. The measured results show that the isolation and conversion loss of the mixer over the frequency band is 20dB and 10.5dB, respectively. The LO input power for operating the proposed mixer is +3dBm, which is lower than a general conventional mixer's LO power. The 1 dB compression point is 6dBm.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.23-28
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• 2003

In this paper, a triple-band planar antenna is proposed for the application to miniaturized automobile safety devices operating at X band(10.5 ㎓), K band(24.15 ㎓), and Ka band(34.3 ㎓). The frequency ratio between the resonant frequencies of this antenna can be adjusted from 1.99 to 2.23 for both X band and K band by varying its slit length. Parasitic elements are added on the modified slot loaded antenna to obtain the third resonance. From numerical as well as experimental results, it has been confirmed that this type of antenna is appropriate for planar multi-band antenna systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1223-1231
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• 2010

The design is presented for a SATCOM antenna capable of simultaneous multi-band (X/Ku/Ka-Band) communications without replacement of feed horns or change of other parts in the application as a ground satellite terminal for large data transfer. The antenna is the offset configuration and consists of a dual-band(X/Ka-band) feed horn, a single-band(Ku-band) feed horn, a frequency selective surface(FSS) sub-reflector and a parabolic main-reflector. The antenna has a main reflector defining a prime focus and a frequency selective surface sub-reflector defining an image focus. A dual-band feed and a single-band feed are provided at each of the prime focus and image focus. The antenna is designed using 3D EM simulator and the gains measured in X/Ku/Ka-band of the complete antenna assembly is more than 31.6dBi, 36.8dBi, 40.8dBi, and the cross polarization is 21.7dB, 26.6dB, 25.2dB, respectively.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.348-355
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• 2006

In this paper, frequency multipliers used S-band transponder of the KOMPSAT 3 are designed and fabricated. In the transponder, 108 times multiplier which generate 1st LO signal(2008.8MHz) is comprised of the X9 frequency multiplier, 1st X2 multiplier, 2nd X2 multiplier and the last stage of the X3 frequency multiplier. As results, output power of 8.17 dBm at 2008.8MHz, the harmonic suppression of -56.67dBc, the bandwidth of 14MHz were measured.

• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.164-168
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• 2016

A dual-band through-the-wall imaging radar receiver for a frequency-modulated continuous-wave radar system was designed and fabricated. The operating frequency bands of the receiver are S-band (2-4 GHz) and X-band (8-12 GHz). If the target is behind a wall, wall-reflected waves are rejected by a reconfigurable $G_m-C$ high-pass filter. The filter is designed using a high-order admittance synthesis method, and consists of transconductor circuits and capacitors. The cutoff frequency of the filter can be tuned by changing the reference current. The receiver system is fabricated on a printed circuit board using commercial devices. Measurements show 44.3 dB gain and 3.7 dB noise figure for the S-band input, and 58 dB gain and 3.02 dB noise figure for the X-band input. The cutoff frequency of the filter can be tuned from 0.7 MHz to 2.4 MHz.

• Journal of the Korean Institute of Navigation
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• v.23 no.3
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• pp.29-34
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• 1999

In this paper, an X-band power amplifier using GaAs FET was designed and fabricated, which is to be used as SART transmitter sweeping at the frequency range of 9.2 GHz~9.5 GHz. The amplifier is consist of two stages using ATF-46101 FET of Hewllett-Packard. Finally, the amplifier using microstrip line matching solution shows that MAG is 23 dB at the center frequency of 9.35 GHz.

• Journal of Advanced Technology Convergence
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• v.3 no.3
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• pp.9-15
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• 2024

This paper details research on the optimized design and fabrication of a 4x4 microstrip array antenna intended for X-Band applications. The study focuses on achieving the desired resonance frequency and gain by modifying the microstrip patch and array antenna parameters, including substrate type and patch size. It presents results from designing and fabricating a 4x4 array antenna with optimum substrate materials to enhance X-Band resonance characteristics and gain. The antenna dimensions are 10mm(W)x7.4mm(L)x 0.79mm(H), with an Rogers RO 4350B dielectric substrate (ε_r=3.54) and an inset-fed feeding method to minimize antenna size. Both the single patch and 4x4 array antennas demonstrated stable SWR (<1.5) and a gain of 18.5dBi at the target frequency of 10.3GHz in simulations. The fabricated antenna showed performance consistent with simulation results. This antenna design is suitable for X-Band applications, including military, satellite communications, and biomedical fields.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.557-562
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• 2017

In this paper, we show the design of a rotary joint transition for the X-band channel in a rotatable microwave communication system. The transition seems complicated to make a channel between two coaxial cables through a cylindrical waveguide. To make a broad-band performance in the X-band with low insertion loss and return loss given the constraint on the length and radius of this complicated-looking cylindrical structure, Genetic Algorithm optimization is adopted to check the validity of an intensive parametric study in the design. The structure is fabricated and tested to show how valid the design method is as well as good frequency responses.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.2
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• pp.71-77
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• 1982

This poper proposes the method of the balanced-mixer realization in the X-Band frequency range by the MIC coplanar magic-tee. This magic-tee is composed with microstrip and slot, as suggested by Ronde. The characteristics of balancing and isolation in this magic-tee is more preferable to those of the rat-race or hybrid ring in the wide frequency range. So, experimentally in this paper the characteristics of the MIC balanced-mixed are obtained with the VSWR less than 1, 2(in Local and Signal Arms) and the Conversion Loss, 6 dB in that frequency range, when the mixer is designed in the 3rd order (in E-arm) and 2nd order(in H-arm) Chebyshev matching networks, and with two symmetrical Schottkey Barrier Diodes.