• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.927-932
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• 2024

In this paper, the waveguide filter is realized by using the 3D printing and electroplating process. The waveguide filter is consisted of the resonator and the inductive window. The resonator is made small by putting vertical pillar inside the cavity. In case of in/output, the pin of SMA connector is connected to the pillar using the tapped-line method. Designed filter has the volume of 24.0 x 58.0 x 38.0 mm3 that is about 91% reduced compared to general cavity filter. Designed filter is modeled divided into upper part that has the inductive window and lower part that has the pillar. Printed filter by the ABS plastic is plated with 10㎛ thick copper over nickel electrodes. Fabricated filter is measured with the center frequency of 2.397GHz and bandwidth of 4.76%. Also, the insertion loss of filter has 0.15dB and return loss is shown under the 20dB. Suggested waveguide filter with pillar and manufacturing process allows the waveguide devices to be made small, lightweight, and low-cost and can be applied to various RF system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.288-293
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• 2003

In this paper, Filter could use to IMT2000 repeater using resonator of Comb-line form that has waveguide structure and designed. Coupled resonators designed using slot in wall between resonators to compact. 5-stage resonators have equal structure and input and output part was optimized to get into minimum impedance. Band pass filter characteristic satisfied design condition as result that used Chebyshev function that have 0.2 dB ripple and analyze using simulation tool.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.26-31
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• 2005

In this paper, a small BPF(band pass filter) is designed using new probe type for wireless communication system. The dielectric resonator is used high Q ceramics for low loss characteristic. In order to provide a band pass filter which can be reduced in dimension, can be reduced in height, and can be surface-mounted. The filter was fabricated using $TE_{01{\delta}}$ mode dielectric resonator. The input/output probes are attached to coner portion of the rectangular metal cavity. Results of the manufactured filter($12{\times}12{\times}8[mm]$) show that the center frequency is 9.95358[GHz], the insertion loss is -1.9[dB], the 3[dB]_bandwidth is 14.9[MHz], and the loaf Q is 664.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.287-293
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• 2004

A numerical simulation is presented for investigating the effects of pressure ratio of $D_2$ injector to supersonic nozzle on the population inversion in the DF chemical laser cavity, while a lasing concurrently takes place. The laser beam is generated between the mirrors in the cavity and it is important to obtain stronger population inversion and more uniform distribution of the excited molecules in the laser cavity in order to produce high power laser beam with good quality. In this study, these phenomena are investigated by means of analyzing the distributions of the DF excited molecules and the F atom used as an oxidant, while simultaneously estimating the maximum small signal and saturated gains and power in the DF chemical laser cavity. For the numerical solution, an 11-species (including DF molecules in various excited states of energies), 32-step chemistry model is adopted for the chemical reaction of the DF chemical laser system. The results are discussed by comparison with two $D_2$injector pressure cases; 192 torr and 388.64 torr. Major results reveal that in the resonator, stronger population inversions occur in the all transitions except DF(1)-DF(0), when the $D_2$injection pressure is lower. But, the higher $D_2$injection pressure provides a favorable condition for DF(1)-DF(0) transition to generate the higher power laser beam. In other words, as the pressure of $D_2$injector increases, the maximum small signal gain in the $V_{1-0}$ transition, which is in charge of generating most of laser power, becomes higher. Therefore, the total laser beam power becomes higher.r.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.261-273
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• 2014

In this paper, metal insulator metal (MIM) plasmonic slot cavity narrow band-pass filters (NBPFs) are studied. The metal and dielectric of the structures are silver (Ag) and air, respectively. To improve the quality factor and attenuation range, two novel NBPFs based on tapered structures and double cavity systems are proposed and numerically analyzed by using the two-dimensional (2-D) finite difference time domain (FDTD) method. The impact of different parameters on the transmission spectrum is scrutinized. We have shown that increasing the cavities' lengths increases the resonance wavelength in a linear relationship, and also increases the quality factor, and simultaneously the attenuation of the wave transmitted through the cavities. Furthermore, increasing the slope of tapers of the input and output waveguides decreases attenuation of the wave transmitted through the waveguide, but simultaneously decreases the quality factor, hence there should be a trade-off between loss and quality factor. However, the idea of adding tapers to the waveguides' discontinuities of the simple structure helps us to improve the device total performance, such as quality factor for the single cavity and attenuation range for the double cavity. According to the proposed NBPFs, two, three, and four-port power splitters functioning at 1320 nm and novel ultra-compact two-wavelength and triple-wavelength demultiplexers in the range of 1300-1550 nm are proposed and the impacts of different parameters on their performances are numerically investigated. The idea of using tapered waveguides at the structure discontinuities facilitates the design of ultra-compact demultiplexers and splitters.

• ETRI Journal
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• v.32 no.2
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• pp.195-203
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• 2010

A new vertical transition between a substrate integrated waveguide in a low-temperature co-fired ceramic substrate and an air-filled standard waveguide is proposed in this paper. A rectangular cavity resonator with closely spaced metallic vias is designed to connect the substrate integrated waveguide to the standard air-filled waveguide. Physical characteristics of an air-filled WR-22 to WR-22 transition are compared with those of the proposed transition. Simulation and experiment demonstrate that the proposed transition shows a -1.3 dB insertion loss and 6.2 GHz bandwidth with a 10 dB return loss for the back-to-back module. A 40 GHz low-temperature co-fired ceramic module with the proposed vertical transition is also implemented. The implemented module is very compact, measuring 57 mm ${\times}$ 28 mm ${\times}$ 3.3 mm.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.337-342
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• 2004

Laser optical power stabilization of a radio frequency excited $CO_2$ slab laser using the opto-Hertzian effect generated from the laser itself is achieved on the peak of the Doppler broadened gain curve. The opto-Hertzian signal was generated by a modulation of the optical flux circulating inside the laser cavity from a variation in the cavity length caused by the vibrations of the PZT. The opto-Hertzian signal is directly coupled from a RE discharge chamber via a loop antenna into a detector and applied to a lock-in stabilizer as an reference signal. The power stability of an RF excited slab laser is estimated to be better then 0.2%.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1759-1761
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• 1996

Md:YAG laser has been used in many applications such as micromachining, nonlinear optical experiments, holography, and rangefinding. These applications quite often require operation of the laser at the $TEM_{00}$ mode since this mode produces the smallest beam divergence, the highest power density, and, hence, the highest brightness. In this study, a pinhole is put between a rod and a half mirror to make the $TEM_{00}$ mode, and then we measured the intensity distribution of the output beam as reducing the diameter of the pinhole from 6mm to 1.5mm. As a result, the optimum size of the pinhole fixed in a resonator to make the $TEM_{00}$ mode was obtained, and we found out that the output beam of the pulsed Nd:YAG laser with a single elliptical cavity has a Gaussian distribution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.1048-1058
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• 1996

In this paper, a small duplexer is designed and implemented using a H-plane T-junction and Transmitting/Geceiving filte with a dual mode cavity resonator for Ku-band. Transmitting(TX) filter is designed at center frequeny 12.5 GHz and Receiving(RX) filter, at center frequency 14.5 GHz. Both filters have a 100 MHz bandwidth. This duplexer is reduced to about 40% by the conventional duplexer of cavity bandpass filter structure in size. Operating characteristics of duplexer is optimized in order not to distors matching characteristics of each filter when interfaced to a H-plane T-junction. Consequently, the responses of filter with H-plane T-junction nearly coincide with that of filter itself.