• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.406-412
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• 2018

In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.71-79
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• 2001

The use of a glass-plate probe of rectangular shape is proposed for the measurement of transmission loss in optical waveguides. The light-collecting window is of a thin, rectangular shape and is perpendicular to the light streak, while the conventional fiberglass probe has a small circular face. This transversely elongated form results in a grate improvement of mechanical tolerance for the probe movement in the vortical as well as in the transverse direction. A theoretical investigation also presents a reasonable agreement with the experiments.

• 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.

• ETRI Journal
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• v.21 no.2
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• pp.1-8
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• 1999

We analyze the characteristics of a coaxial-to-waveguide transition based on the finite difference time domain (FDTD) method with the cylindrical to rectangular cell interpolation scheme. The scheme presented in this paper is well suited for the analysis of a microwave device with a probe near waveguide discontinuity because perfect TEM mode can be generated inside the coaxial cable by using the cylindrical cell. The scattering parameters of a designed Ka-band transition are evaluated and compared with those of commercially available software, High Frequency Structure analysis Simulator (HFSS) and measured data. There exists good agreement between the measured and calculated data. In order to prove an accuracy of the interpolation scheme, a coaxial to waveguide transition with a disk-loaded probe is analyzed by the present approach and the results of this analysis are compared with measured data. Comparison shows that our results match very closely to those of measurement and other approaches. The method presented in this paper can be applied to analyze the characteristics of a probe excited cavity, coaxial waveguide T-Junctions, and so on.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.565-568
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• 2007

In this paper, we designed and fabricated a broadband probe with a double-ridged waveguide for broadband near-field measurements. An exponentially tapered ridge in the rectangular waveguide and a novel waveguide transition were used for broadband impedance matching. The probe has broadband characteristics and its measured impedance bandwidth is approximately 123% (4.17:1) in the range 12.0-50 GHz for standing wave ratios (SWR) < 3.0. The peak radiation gain range and nominal radar cross-section (RCS) are 5.7-14.3 dBi. The performance of this probe was verified using the measured results and is in good agreement with the simulated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1300-1305
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• 2014

Equivalent circuits for the waveguide probe with H-shaped small aperture, as a key ingredient of near field microwave microscope, is described along with a working principle of the probe. Small rectangular or circular aperture in comparison with the wavelength behaves like the inductive element. So adding the ridged structure (corresponding to capacitive component) to the small aperture allows the transmission resonance to occur. For verification, we represents the equivalent circuit descriptions for the two types, ridged aperture and cavity types. The values of obtained by use of the equivalent circuit approaches are compared with those obtained by use of the available numerical software. The results are also experimentally verified.

• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.1-15
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• 1993

We made a pyramidal horn antenna system for 21cm cosmic radio wave. The antenna system has a rectangular waveguide with $TE_{10}$ mode and a copper probe to detect the electromagnetic wave in waveguide. The parameters of the probe are obtained by experiments using two waveguides. Pyramidal horn antenna is designed to get a gain of 20dB. The size of the aperture of this horn is $94cm{\times}74cm$. The beam width of half power is about $14.7^{\circ}$ for the frequency of 1.4GHz. The horn is made of aluminum plate with a thickness of 2mm. The signal from horn and waveguide is amplified in a receiver system and is converted into DC in the detecter. The intensity of the signal is recorded on a chart recorder. We observed the sun using this simple radio telescope and obtained the brightness temperature of $2.2{\times}10^5K$, which indicates that the sun is quiet at 21cm.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.1
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• pp.43-47
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• 2015

In this work, a broadband microstrip (MSL) - to - waveguide (WR12) transition has been presented for millimeter-wave module applications. For improvement of a bandwidth, the radial MSL electrical-probe is designed on the low-loss organic dielectric substrate. The designed and tested characteristics of the proposed transition are characterized in terms of an insertion and return loss. Considering the loss contribution of the cable adapter and waveguide transition for the measurement, the proposed transition loss can be analyzed as -1.88 and -2.01 dB per a transition at 70 and 80 GHz, respectively. The bandwidth of the proposed transition for reflection at -10 dB is 26 GHz at all test frequencies from 67 to 95 GHz. Compared to the state-of-the-art results, improvement of 8.3 % is achieved for the operation bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.836-844
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• 2006

In this paper, we designed and fabricated the wideband probe with double ridged waveguide for Near-field Measurement. An exponential taper ridge in the rectangular waveguide was implemented for wideband impedance matching. It has wideband characteristics and its measured impedance bandwidth ratio is approximately 2.2:1 from 8.2 GHz to 18 GHz for $VSWR\leq2.2$. It maintains about the same radiation pattern over the entire bandwidth and has more than 4.5 dBi peak radiation gain. Our designed probe was applied to near-field measurement. A good agreement has been found between simulated and measured results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.14 no.1
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• pp.29-33
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• 1977

Impedance of a post mount structure supporting a microwave diode in the X-band rectangular waveguide is calculated by using the induced EMF method. Probe measurement of the driving point impedance of the post mounu shows a close agreement with the theoretical calulation when the gap of the post mount is near the bottom wall of the waveguide.