• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.187-192
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• 2008

The design and analysis of a novel photonic crystal electro-optic modulator are presented in this paper. The device incorporates an electro-optic (EO) polymer slot waveguide into the center of a silicon photonic crystal waveguide. In this device, strong optical confinement in the EO polymer core and small group velocity from the photonic crystal structure provide a surprise enhancement of the EO effect.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.82-89
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• 2007

This paper presents a coplanar waveguide fed L-planar type monopole antenna which covers ultra wideband(UWB) region of 3.1 GHz to 10.6 GHz. The proposed UWB L-planar type monopole antenna is designed and implemented on the organic substrates( ${\varepsilon}_{r}=3.38,\;@10\;GHz$). The radiation elements, feed line, and ground planes of the antenna are printed on the same conductive layer of the substrates. The bandwidth of the proposed antenna is measured in the range of 3.0 GHz to 11.0 GHz. The measured radiation patterns are symmetrical in E-plane and omni-directional in H-plane. Antenna gains ranges from 1.4 dBi to 4.6 dBi. The proposed UWB antenna shows that the structure is adequate for the design of RFIC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.912-918
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• 2011

In this paper, a composite right-/left-handed(CRLH) rectangular waveguide satisfying a balanced condition above the cut-off frequency is presented. The proposed structure consists of one shorted stub and two twisted H-plane irises which produce an effectively negative permeability and permittivity, respectively. The CRLH structure can independently control the series and shunt resonance frequencies of a CRLH transmission line which determine the left-handed(LH) and right-handed(RH) bands due to a minimized coupling between a shorted stub and twisted H-plane irises. Thus, the design of the CRLH waveguide satisfying a balanced condition is possible. To analyze the CRLH structure, a crossly connected equivalent circuit is derived. The simulated and measured results confirm that the proposed CRLH waveguide has a transmission property without a band gap among the LH and RH bands.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.7-13
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• 2014

In this paper, a novel waveguide low pass filter for satellite communication is proposed. The proposed low pass filter is designed to obtain wideband characteristics without the interference of higher order modes, sufficient attenuation in the stop-band and small sized lightweight characteristics by evanescent-mode ridge structure. To improve return loss and rejection loss, rectangular ring is inserting around the ridges in the waveguide. Input and output ports of the low pass filter is designed by using the impedance step structure for the impedance matching of the filter. The proposed waveguide low pass filter is fabricated and then measured as return loss over 19.5 dB, insertion loss less than 1.41 dB at the pass-band of 7.25 ~ 8.4 GHz and rejection loss over 67.2 dB at the stop-band of 12.25 ~ 14.5 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.525-532
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• 2015

In this paper, we propose an equivalent model of array antennas that use open-ended waveguides for effective EM simulation. We first investigate an individual element that consists of an open-ended waveguide and square ground plane. The waveguide length, aperture size, and ground size of the individual element are adjusted to give a similar radiation pattern to that of the individual element of the original antenna. We then apply the designed equivalent model to two different types of array antennas, such as a microstrip patch array and a waveguide array antenna. Comparison of the simulation results using the equivalent model with the results obtained with the original antenna reveals a difference in gain of less than 0.2 dB and a difference in half power beam width(HPBW) of less than $1^{\circ}$. The designed equivalent model is then mounted on a simple aircraft, and the simulation results are again compared to results from the original antenna. We find a 60 % reduction in simulation resources and time when compared with the original antenna model.

• Journal of Sensor Science and Technology
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• v.29 no.3
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• pp.172-179
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• 2020

We studied an integrated-optic biosensor configuration that operates at a wavelength of 0.63 ㎛ based on the evanescent-wave and two horizontal mode power coupling of Si₃N₄ rib-optical waveguides formed on a Si/SiO₂/Si₃N₄/SiO₂ multilayer thin films. The sensor consists of a single-mode input waveguide, followed by a two-mode section which acts as the sensing region, and a Y-branch output for separating the two output waveguides. The coupling between the two propagating modes in the sensing region produces a periodically repeated optical power exchanges along the propagation. A light power was steered from one output channel to the other due to the change in the cladding layer (bio-material) refractive index, which affected the effective refractive index (phase-shift) of two modes through evanescent-wave. Waveguide analyses based on the rib optical waveguide dimensions were performed using various numerical computational software. Sensitivity values of 12~23 and 65~165 au/RIU, respectively for the width and length of 4 ㎛, and 3841.46 and 26250 ㎛ of the two-mode region corresponding to the refractive index range 1.36~1.43 and 1.398~1.41, respectively, were obtained.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.19-26
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• 2021

This report proposes a waveguide spatial combiner with high power low loss. The proposed spatial combiner implements high power by combining from the center of each port through a waveguide. In particular, we implement low loss using TE01 mode, which has the lowest transmission track loss among modes of circular waveguide, and miniaturization is achieved by applying a new mode conversion method. IIn addition, it was confirmed that it was suitable for high output by calculating the insulation breakdown voltage of the new mode conversion structure through E-field analysis. The final 8-way waveguide spatial combiner was designed and manufactured, and the insertion loss was less than 0.4dB and the combining efficiency was 97% or more, confirming that the electrical performance was very good compared to the planar combining method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.35-42
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• 2022

In this paper, a method to increase the combining efficiency and isolation of the combiner, the core module of SSPA (solid state amplifier), was studied. Specifically, the isolation was secured by matching the common port and the isolation port in the waveguide combiner. The matching structure for matching is in the form of a circular disk and is engraved inside the waveguide combiner. The structure is very simple, so it is possible to secure stable performance. And this structure showed more than 60 times higher critical power performance compared to previous studies, confirming that it is suitable for high output. And by combining 1-stage T-junction and 2, 3 stage MagicT combiner, miniaturization was achieved and the combining efficiency was optimized by reducing the insertion loss. The fabricated waveguide coupler obtained an isolation of 16dB or more and a coupling efficiency of 86.2%.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.2
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• pp.107-111
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• 2014

An SIW cavity is a useful tool to design an FSS which shows a rapid roll-off rate and insensitivity to polarizations and incident angles of electromagnetic waves. However, due to its high Q-factor, the FSS also shows narrow bandwidth which is undesirable for high-capacity communication. To address this drawback, we propose a novel technique to enhance the bandwidth while maintaining similar frequency response characteristics and minimizing the increase of the overall thickness of the SIW cavity FSS. In order to verify the performance of the technique, simulated frequency responses will be provided. Also, a parameter which affects the bandwidth will be studied. Finally the stability to polarizations and incident angles will be observed through the simulated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.487-490
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• 2014

This paper describes a design of an automotive radar frontend module with taking care of the routing of 77-GHz signals on a printed circuit board including wire-bond and waveguide transitions.