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A phase-locked loop (PLL) array has been developed to perform electronic beam steering at W-band (76–77 GHz) for radar applications. It uses external current injection into the outputs of the charge pump (CP) in the frequency synthesizers to adjust the phase of the voltage control oscillators (VCO) in the PLL array. The measurement array radiation pattern is presented.
In order to improve the accuracy in near-field passive location systems that are based on distributed fiber sensor array, we propose a method to correct the tropospheric error The method utilizes the Hopfield refractivity profile model for the near-filed targets. Simulation results show that the proposed algorithm could quickly converge with improved precision.
A two-dimensional model was established to study the dynamic characteristics of a quartz crystal resonator with the upper surface covered by an array of hemispherical material units. A frequency-dependent equivalent mass ratio was proposed to simulate the effect of the covered units on frequency shift of the resonator system. It was found that the equivalent mass ratio alternately becomes positive...
In direction-of-arrival (DOA) estimation using millimeter waves or ultrasonic, the physical size of the sensors can require inter-element spacing of greater than half wavelength. The accompanied benefits of such spacing are larger array aperture and reduced mutual coupling, but the serious problem of DOA ambiguity arises. This paper proposes a method to suppress grating lobes by employing a MIMO radar...
Calcification is one of the important indicators for early breast cancer detection. Although X-ray mammography is the well-established gold standard method for identifying microcalcifications (i.e., smaller than 0.5 mm), it is with ionizing radiation and thus there is inevitably carcinogenic risk. Ultrasound (US) imaging is a powerful adjunct to X-ray mammography for imaging of breast lesions. However,...
A photonic approach using an optical filter array is proposed to perform instantaneous frequency measurement with digital outputs. 4-bit digital outputs are then experimentally demonstrated within the range of 20~40 GHz.
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