• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1740-1746
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• 1997

In this paper, a waveguide-fed slot-coupled microstrip antenna is proposed as enhanced feeding structure of microstrip antenna and an analysis is presented. The presence of dielectric substrate between a stripand a slot is explicitly taken into account in this analysis. The evaluation of the antenna characteristics is carried out using the method of mements and the spectral domain approach in terms of the electric current distribution on the strip and the magnetic current distribution on the slot. From the results, we can conclude that the proposed structure is adequate for array antennas, due to ease of mass porduction and enhanced anteena performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.1
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• pp.36-49
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• 1987

A planar waveguide model is presented for calculating dispersion characteristics of the normalized phase velocity and characteristic impedance with the frequency dependent effective dielectric constand and effective width in microstrip lines of the hybrid mode. Eeff(f) and Weff(f) are applied to a planar waveguide model by using an empirical relations and formula designed for CAD purposes as a function of frequency. A wide range of relative dielectric constants and the strip $h_{width}$strate height(W/h ratios), $0.5$\leq$W/h\leq2.5$ are used. These results are compared with static value, spectral domain analysis, and empirical results. As the result of a computer simulation, in the case of using a planar waveguide model, the frequency dependent normalized phase velocity is more closely approached to 1/ and characteristic impedance is more increased than the other method that has already been presented as the increasing of the frequency. And, the case of applying Eeff(f) designed for the purpose of CAD to this proposed model is show in better result than the case of using a empirical relations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.266-269
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• 2018

A compact Q-band waveguide-to-microstrip transition for UAV(Unmanned Aerial Vehicle) radiometer applications is presented. The key features of this transition are simplicity, compactness, easy matching, and lower sensitivity to the dimensions and fabrication tolerances. The simple E-plane patch-type design is insensitive to the backshort cavity enclosure and misalignment between the waveguide and microstrip substrate. The primary parameters are optimized using a three-dimensional(3D) electromagnetic simulator(ANSYS HFSS). It exhibited better than 20-dB return loss at mid-band frequencies with less than 1-dB insertion loss for the back-to-back transition, and a return loss better than 15 dB over the frequency range of 36 GHz to 42 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.4
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• pp.47-52
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• 2012

We have designed the waveguide to microstrip transition using a probe structure for the center frequency of 200 GHz transceiver. The waveguide to microstrip transition is composed of probe, taper and microstrip transmission line. For design of the transition, we simulated the lengths and width of the probe and the taper to optimize the center frequency and the bandwidth using HFSS simulation tool from Ansoft. The transition is designed back-to-back structure. From the simulation results, the transition exhibits that insertion loss is below - 0.81 dB and the return loss less than -10 dB in range of 186 ~ 210 GHz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.37-42
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• 2022

A high-performance wideband transition from microstrip to waveguide is proposed. This transition is designed by consideration of gradual field transformation and optimal impedance matching between microstrip line and fin-line. Clear design guidelines of proposed transition using fin-line taper with offset DSPSL (double-sided parallel stripline) are provided to determine the transition shape and the transition length. The fabricated transition exhibits less than 0.67 dB insertion loss per transition for frequencies from 85 to 108 GHz, and less than 1 dB insertion loss from 83 to over 110 GHz. Proposed transition is expected compact radar and various applications.

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

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.49-54
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• 2001

In this work, we developed a Ka-band hybrid 4-stage power amplifier module using GaAs pHEMTs and waveguide to microstrip transitions. It has high gain and high output power characteristics. We used a 10 mil- thickness duroid substrate to fabricate this power amplifier and waveguide to microstrip transitions. The fabricated waveguide to microstrip transition showed about 1 dB insertion loss(back to back) at 32 40 GHz. The measured results of power amplifier module showed over 1W output power at 36.1 - 37.1 GHz. And it showed 31 dBm output power, 24 dB power gain and 15 % power-added efficiency(PAE) at 36.5 GHz.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.257-260
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• 2014

In this paper, a high gain waveguide array antenna combining horn antenna on slot radiator was designed. And the fabricated antenna showed enough gain, improved efficiency and broadband characteristics for receiving satellite signals, compare to conventional microstrip antenna which has dielectric loss and radiation loss on transmission line. For easy fabrication, the waveguide structure was composed by 3-stages of radiator, signal coupler and transmission line. By experiment, the array waveguide antenna of 4 by 16 showed 28.3[dBi] gain and 2:1 of VSWR. And by combining horn antenna structure, the gain was increased 1[dB]. The received signal from Koreasat 6 by measurement showed 16[dBc] of C/N on BS(Broadcasting Satellite)-band and 14[dBc] of C/N on CS(Communication Satellite)-band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.688-696
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• 2005

An antenna was designed and manufactured for the DBS receiver system. This antenna is a planar or flat antenna which shows many advantages over the conventional parabolic antenna such as higher aperture efficiency, easier installation and improved aesthetics to name a few. The antenna is a novel design employing microstrip annular ring resonating antenna elements and a radial waveguide feeder network. The LNB(Low Noise Blockdown Converter) is can integrate with the antenna iしt the back of the radial waveguide. The 35cm diameter antenna works at 31.8dBi minimum gain which implies an aperture efficiency of around $80\%$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.76-84
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• 2012

In this paper, two kinds of E-plane microstrip-to-waveguide transitions are optimally designed and fabricated for combining output power from multiple small-power amplifiers in a WR-28 waveguide because conventional K connectors cause unnecessary insertion loss and adaptor loss. The transition design is based on target specifications such as a center frequency of 35 GHz, bandwidth of ${\pm}500MHz$, 0.1 dB insertion loss and 20 dB return loss. Performance variation caused by mechanical tolerance and assembly deviation is fully evaluated by three dimensional electromagnetic simulation. The fabricated back-to-back transitions with 16 mm and 26.57 mm interstage microstrip lines show insertion loss per transition of ~0.1 dB at 35 GHz and average 0.2 dB over full Ka band. Also the back-to-back transition shows return loss greater than 15 dB, which implies that the transition itself has return loss better than 20 dB.