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Michitaka Ameya - IEEE Xplore Author Profile

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We develop an undersampling measurement technique for metasurface reflectors based on Gaussian process regression (GPR) beyond the sampling theorem limitation. For characterizing near-field scattering distribution data to determine the bistatic radar cross section of a reflector using near-field to far-field transformation, we propose an iterative GPR algorithm that consists of data estimation at ...Show More
The near-field to far-field transformation method is a well-established measurement technique that achieves high-accuracy far-field antenna radiation patterns from near-field data. However, this method is often time-consuming. This paper proposes an efficient sampling method using Gaussian process regression to calculate far-field data. By employing 86% undersampled near-field data with a sampling...Show More
We have newly developed a millimeter-wave vector measurement system for an oscillator-integrated antenna using a time-domain measurement setup. The measurement system consists of two mixers, one for the antenna pattern measurement and one for the phase reference measurement. In this paper, we show the developed W-band millimeter-wave measurement system configuration. In addition, we show the measu...Show More
We have newly developed a millimeter-wave band vector measurement system using a time-domain measurement setup. The system consists of an optical fiber link millimeter-wave transmission system, an IF substitution method configuration as a receiving system, and a low-frequency band-type oscilloscope. In this paper, we show the developed millimeter-wave measurement system configuration. Then, we dem...Show More
We have already developed an optical fiber link millimeter-wave measurement system. The millimeter-wave measurement system consists of an optical fiber link millimeter-wave generator and an optical fiber link millimeter-wave receiver. The millimeter-wave generator and the millimeter-wave receiving system use an optical harmonic wave generation technique that consisting of a LiNbO3 optical intensit...Show More
We propose the use of Gaussian process regression to derive the far-field coupling product between antennas in the three-antenna extrapolation method. Since Gaussian process regression yields a covariance matrix of the estimated values, it is possible to discuss how the position of the transmission S-parameter measurement and the number of measurement points in the extrapolation method affect the ...Show More
We propose dual-band anomalous reflectors operating at 220 GHz and 293.3 GHz for 6G applications. The anomalous reflectors consist of paired patch elements on single-layer and via-free substrates. Based on a local reflection phase design and optimization of paired patch elements, higher-order diffraction modes can be controlled simultaneously at the two harmonic frequencies to achieve highly effic...Show More
In 6G wireless communication systems, the use of array antennas and metamaterial reflectors above 100 GHz is being considered to expand the communication area, and there is an urgent need to establish a high-precision evaluation system for array antennas and metamaterial reflectors, which are key components for 6G wireless systems. To meet these demands, we have developed a compact antenna test ra...Show More
We have newly developed an optical fiber link millimeter wave band vector measurement system. The system consists of an optical fiber link millimeter wave transmission system, an optical fiber link millimeter wave receiving system, and the IF substitution method configuration using a lock-in amplifier (without a vector network analyzer). In this paper, we show the developed millimeter wave measure...Show More
We have already developed a millimeter wave signal generator using an optical harmonic generation technique for a LiNbO3 Mach-Zehnder optical intensity modulator (LN modulator). Our developed optical fiber link millimeter wave generator can generate a millimeter wave of an input frequency and 2 x n times the input frequencies for the LN modulator. If the input frequency of the optical intensity mo...Show More
We have newly developed a W-band millimeter wave signal generator using an optical second-order harmonic generation technique for a LiNbO3 Mach-Zehnder optical intensity modulator. For generating the millimeter wave from 75 GHz to 110 GHz, our developed signal generation technique uses the signal generator from 18.75 GHz to 27.5 GHz, a microwave amplifier, the LiNbO3 Mach-Zehnder optical intensity...Show More
We have developed a simple antenna gain estimation method using a millimeter-wave FMCW radar as a transmitting antenna from 77 GHz to 80 GHz. Our developed system consists of a millimeter-wave FMCW radar, a standard gain horn antenna as a calibrated reference antenna, a signal analyzer, and a W-band mixer.Show More
We have developed an all-optical fiber link antenna measurement system using an industrial robot system for 28 GHz band of 5th generation mobile communication. Our developed system consists of an optical fiber link microwave transmitting system, an antenna-coupled-electrode electric-field (EO) sensor system for 28 GHz-band as a microwave receiving system, and a 6-axis vertically articulated robot ...Show More
We have estimated a far field antenna factor of an antenna-coupled-electrode electric-field sensor system for 28 GHz-band using an amplitude center modified Friis transmission formular. Estimated far field antenna factor of the sensor system is 70.25 dB/m at 28 GHz.Show More
We have newly developed a millimeter wave signal generator using an optical second-order harmonic generation technique for a LiNbO3 Mach-Zehnder optical intensity modulator. For generating the millimeter wave from 50 GHz to 77 GHz, our developed signal generation technique uses the signal generator from 12.5 GHz to 19.25 GHz, a microwave amplifier from 12.5 GHz to 19.25 GHz, the LiNbO3 Mach-Zehnde...Show More
We have newly developed a microwave signal generator for the 28 GHz band of 5G mobile communication using an optical high-order harmonic microwave generation technique. Our developed generator consists of a DFB laser diode, a LiNbO3 Mach-Zehnder optical intensity modulator, a signal generator from 13 GHz to 15 GHz, and a photo diode. In the case of the input frequency range from 13 GHz to 15 GHz t...Show More
We have developed an antenna-coupled-electrode electric-field sensor for 28 GHz-band in 5th generation mobile communication as a receiving antenna [1] . In this paper, we report a 3D near field receiving pattern for the simultaneously-receiving dual-polarized type electric-field sensor and a linear-polarized type electric-field sensor that have 2 and 2by 2 array antennas respectively. The electric...Show More
We design an impedance-matched reflectionless metasurface to manipulate the aperture phase of an X-band large-aperture slot array antenna. By proposing a design procedure for large-area metasurfaces in practical applications with preparing a database that relates the propagation characteristics of unit cells with their physical structures, we design a large-area non-periodic reflectionless metasur...Show More
We have developed multi-probe near-field antenna measurement system using optical-fiber link system. Our developed optical fiber link system consists of a super luminescent diode, zero-biased optical reflection-type electro absorptive modulators (EAM), coarse wavelength division multiplexing (CWDM) multiplexers and photodiodes. Our developed near-field antenna measurement system consists of WR-28 ...Show More
The plane-wave synthesis (PWS) methods are proposed to predict the 3-D and 2-D RCS accurately with multiple scattering effects. The 3-D method employs the propagating plane-wave expansion and can be implemented identically as the near-field far-field transformation (NFFFT). Either the single-level or multilevel implementation can be applied, and in the single-level implementation, a single pseudo-...Show More
We have developed near field antenna measurement system using optical fiber link and vertical articulated robot for 5G antenna measurement. Our developed optical fiber link system consists of 850 nm multi-mode VCSEL (Vertical cavity surface emitting laser diode) and PDTIA (Photo diode with transimpedance amplifier). Our optical fiber link system can use for microwave measurement from 100 MHz to 40...Show More
In this report, the element failure detection of array antenna is performed with a minimum number of measurement points while maintaining sufficient accuracy by learning the relationship between excitation coefficients of array antenna and the electric “far-field” pattern by a shallow neural network. When training the neural network, the massive number of training data are generally required. For ...Show More
An application of a single-cut near-field far-field transformation (NFFFT) technique to a linear near-field (NF) measurement is presented. The transformation technique is recently proposed using a two-dimensional (2D) plane-wave expansion and geometrical approximation about the antenna under test (AUT). It allows the single-cut far-field transformation with high flexibility of positions and orient...Show More
In this report, the element failure detection of array antenna is performed with a minimum number of measurement points while maintaining sufficient accuracy by learning the relationship between excitation coefficients of array antenna and the electric near-field distribution by a shallow neural network. When training the neural network, the massive number of training data are generally required. ...Show More