In this paper, we present a topology optimization method for designing plasmonic devices. We employ the function expansion method to express a device structure in a design region because arbitrary structure can be expressed with relatively few design variables. In addition, we employ CMA-ES for optimizing the design variables.
The nonstandard finite difference time domain (NS-FDTD) method is a new high-accuracy FDTD method, but until now, it was applicable only at a single frequency. In this paper, we extend the NS-FDTD method to handle multiple frequencies in one computer run. We apply our new method to analyze the scattering analysis of a large cavity.
The formulation of the magnetized cold plasma in three-dimensional space and in the time domain is described. An analysis of the patch antenna in the magnetized plasma is then performed. The near-field characteristics of the patch antenna, that is, the effects of the Faraday rotation on the linear polarization of the radiated wave, are shown.< >
We review a system that performs accurate computation of body temperature elevation and sweating by combining electromagnetic and thermal analysis with weather forecast data toward the risk assessment and management. We validate our computational code by comparing with different exposure scenarios, and then extend to estimate allowable time of firefighters as a computational example. We also review our newly-designed system for public enlightenment toward reducing heat stroke patients. Finally, we apply the system to estimate the number of patients of heat stroke in summer.
This paper reports on the excellent performance of V-band monolithic high electron-mobility transistor (HEMT) oscillators, and discusses oscillation characteristics on drain bias. With regard to output characteristics, double-hetero (DH) HEMT (especially with a high-density Si-planar doped layer) are superior to single-hetero (SH) HEMT's. A monolithic microwave integrated circuit (MMIC) oscillator has been developed with a planar doped DH HEMT and has achieved the peak output power of 11.1 dBm at a 55.9-GHz oscillation frequency. Phase noise of -85 dBc/Hz at 100-kHz offset and -103 dBc/Hz at 1-MHz offset have been achieved at a drain voltage of 5.5 V and a gate voltage of 0 V. These characteristics have been achieved without any buffer amplifiers of dielectric resonators. This study has revealed that the phase noise decreases as drain voltage increases. This phenomenon is caused by lower pushing figure and lower noise level at a low-frequency range obtained under a high drain voltage. It is because the depletion layer in the channel is extended to the drain electrode with increase of drain voltage, resulting in the small fluctuation of the gate-to-source capacitance. We also investigate low-frequency noise spectra of AlGaAs-InGaAs-GaAs DH HEMT's with different bias conditions. The low-frequency noise decreases for more than 3 V of the drain voltage. A unique mechanism is proposed to explain this phase noise reduction at high drain voltage.
