• 전기의세계
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• v.28 no.4
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• pp.47-52
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• 1979

Total number of resonant modes in a microwave oven cavity may be maximized for a given frequency bandwidth to obtain more uniform power distribution by choosing proper size of the cavity. The total number of modes is calculated for a dielectrically loaded rectangular cavity and its size is suggested here for which the change in the number of modes is less sensitive to the change of dielectric layer thickness and its total number of modes is maximized in a given range of cavity sizes. A prove coupled rectangular cavity is constructed and the total existing modes are measured to see the change of modes depending on the dielectric layer thickness and the cavity size. Surface wave mode existing in the dielectric layer is confirmed by measuring Q and the input impedance of the cavity for this mode, which closely compares with the calculation.

• Progress in Superconductivity
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• v.1 no.1
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• pp.36-41
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• 1999

Methods for mode identification and accurate measurements of the unloaded Q ($Q_0$) of a dielectric-loaded $TE_{01{\delta}}$ mode cavity resonator with HTS endplates are proposed. A resonator with a sapphire rod and $YBa_2Cu_3O_{7-x}$(YBCO) endplates was prepared and its microwave properties were studied at temperatures above 30 K. The $TE_{01{\delta}}$ mode $Q_0$ of the resonator, designed to work as a tunable resonator with variations in the gap distance (s) between the sapphire rod and the top YBCO, was more than 1000000 at s = 0 mm and at 30 K with the resonant frequency of 19.56 GHz. The $TE_{01{\delta}}$ mode $Q_0$ decreases as s increases for s < 2 mm until mode couplings between the $TE_{01{\delta}}$ mode and other modes appeared at s = 2 mm. Significant dependence of the $TE_{01{\delta}}$ mode $Q_0$ on the input and output coupling constants was also observed. Applications of the open-ended $TE_{01{\delta}}$ mode cavity resonator for a tunable resonator with a very high Q as well as a characterization tool for the surface resistance measurements of HTS films are described.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.267-276
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• 1999

A 2 stage 6-pole bandpass filter (BPF) is designed and implemented by using K-band triple-mode cavity. The BPF has an 100MHz bandwidth at the center frequency of 18.5GHz and the response of the filter is Chebyshev function. The cavity filter uses two orthogonal $TE_{113}$ modes and one $TM_{012}$ mode. To obtain a Chebyshev response, the intercavity coupling between the adjacent cavities is accomplished by H-field component of TE modes parallel to slot plate. In this paper, the size and location of intercavity slot are determined by the detailed coupling equation from H-field of TE resonant modes in circular cavity. The measured results agree well with the theoretical one.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.40-46
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• 2006

Latching optical switches and optical logic gates AND and OR are demonstrated, for the first time, by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure, which have not only a low threshold current with 0.65mA, but also a high on/off contrast ratio more than 50dB. By simple operating technique with changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR. The thyristor laser fabricated using the oxidation process achieved a high optical output power efficiency and a high sensitivity to the optical input light.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.856-862
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• 2013

A cavity-backed two-arm spiral antenna for partial discharge diagnosis is presented. The proposed antenna consists of a two-arm Archimedean spiral, a tapered microstrip balun as spiral antenna feed, and a ring-shaped absorber-loaded cavity. The Archimedean spiral antenna is designed for the operating frequency band of 0.3 GHz to 1.5 GHz and fed by the tapered microstrip balun. The cavity is utilized to transform the bidirectional beam into a unidirectional beam, thereby enhancing gain. The ring-shaped absorber is stacked in the cavity to reduce the reflected waves from the cavity wall. The proposed antenna is designed and simulated using CST Microwave Studio. A prototype of the proposed antenna is likewise fabricated and tested. The measured radiation patterns are directional to the positive z-axis, and the measured peak gain is 8.13 dBi at a frequency of 1.1 GHz.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.250-260
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• 2015

Purpose: Dual cylindrical microwave chambers equipped with an ohmic heating tube were designed and fabricated to maximize the electric field strength for expeditious heat treatment of particulate foods. Methods: The efficacy of the combination heater was investigated by simulating the electric field distribution by using COMSOL Multiphysics software. Results: All components of the designed microwave heating unit were suitable for transmitting maximal microwave power to the load. The simulated electric field distribution implied that single-mode microwave heating would be sufficient for the steady generation of a highly localized heating zone in the cavity. During impedance matching, the calculated reflection coefficient ($S_{11}$) was small, possibly implying minimal power loss and wave reflection in the designed microwave heating chamber. Conclusions: This study demonstrates the possibility of concentrating the microwave power at the centerline for a single-frequency microwave, for thermal treatment of multiphase foods without attenuating the microwave power.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.311-316
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• 2003

Effects of pores on the microwave properties in microwave dielectric ceramics were studied by a computer simulation. Scattering matrix S$\_$21/ obtained from the network analyzer was compared to the S$\_$21/ obtained from the simulation. From electric field distribution, the dominant resonant TE$\_$01$\delta$/ mode could be easily determined. The effects of the porosity and pore size inside the dielectrics on the microwave properties were investigated by the HFSS simulation. When the total pore volume remains constantly, the quality factor decreased as the pore size Increases. As the total pore volume of the dielectrics increased. quality factor decreased.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2120-2125
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• 2015

In this paper, a rectangular waveguide probe with a ridge-loaded straight slot (RLSS) is presented for a near-field scanning microwave microscope (NSMM). The RLSS is located laterally at the end wall of the cavity and is loaded on double ridges in a narrow straight slot to improve the spatial resolution compared with a straight slot. The probe consists of a rectangular cavity with an RLSS and a feed section of a WR-90 rectangular waveguide. When the proposed NSMM is located at distance of 0.1mm in front of a substrate without patches or strips, the simulated full width at half maximum (FWHM) of the probe improve by approximately 31.5 % compared with that of a straight slot without ridges. One dimensional scanning of the E-plane on a sample under test was conducted, and the reflection coefficient of the near-field scanning probe is presented.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.3
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• pp.20-25
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• 1975

A microwave oscillator stabilized by a phase-locked loop (PLL) is developed. The PLL system is chosen 'compared with the cavity stabilized oscillator in view of the domestic manufacturing, because special machining and materials are needed for the latter. A sampler with a low pass filter is shown to be used as a phase detector in the PLL, and the sampler capable of sampling up to 4GHz is developed for this use. Frequency stability of about 10-6 is obtained from the developed microwave oscillator, operating at 2.16 GHz with more than 120 milliwatts output power, Ivhereby a crystal oscillator operating at about 110MHz is used as a reference source in the PLL. The capturing range of this oscillator is extended up to its lock-in-range of about 10MHz by employing a search oscillator in the system.

• ETRI Journal
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• v.25 no.2
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• pp.133-139
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• 2003

We studied how the passive intermodulation (PIM) power arising in air cavity filters could be calculated and how the design of the filter could be optimized in order to reduce the amplitude of the PIM signal. To do this, using simulated results, we optimized the various parameters of a filter. PIM in an air cavity filter depends on the power dissipated in its cavities. A reduction of this power loss therefore decreases the PIM power in the air cavity filter. Our experimental results confirm that it is possible to design and produce air cavity filters that generate low PIM signals.