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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
slowly varying envelope approximation the longitudinal phase velocity of traveling microwave is slowed down to almost equal speed of electrons in the interacting electron beam of the tube. slowly varying envelope approximation neglect of the second time and/or space derivatives in the wave equation governing nearly monochromatic/nearly plane-wave electromagnetic fields. slowness surface a plot of the reciprocal of the phase velocity as a function of direction in an anisotropic crystal. SMA connector a subminiature coaxial connector with both male and female versions capable of an upper frequency limitation of about 26 GHz. small computer systems interface (SCSI) a high-speed parallel computer bus used to interface peripheral devices such as disk drives. small disturbance a disturbance for which the equation for dynamic operation can be linearized for analysis. small disturbance stability power system stability under small disturbances, which can be studied by using linearized power system models. small gain theorem a sufficient condition for the robust stability of the closed-loop system. It requires the open-loop operator of the system to have a norm less than one. For linear systems, the small gain theorem guarantees well posedness while in the nonlinear case it should be assumed. The theorem may be highly conservative for structured uncertainties. In some cases the conservatism could be decreased by the use of structured norms. small scale integration (SSI) an early level of integration circuit fabrication that allowed approximately between 1 and 12 gates on one chip. small signal amplifier amplifier designed for amplifying very low level signals. Typically, small signal amplifiers have an AC signal magnitude that is 1/10 the DC value and operate under class A amplifier biasing conditions. small-signal stability See dynamic stability.
Design and simulation of a novel 3-point star rectifying antenna for RF energy harvesting at 2.4 GHz
Published in Cogent Engineering, 2021
J. O Olowoleni, C. O. A Awosope, A. U Adoghe, Okoyeigbo Obinna, Udochukwu Ebubechukwu Udo
A novel 3-point star antenna design has been featured and simulated in comparison to the conventional square microstrip patch antenna design according to performance parameters such as gain, directivity, return loss, radiation pattern and efficiency. From the obtained simulation results, the proposed 3-point star antenna design was shown to exhibit improved performance over the conventional square patch antenna design in terms of gain, directivity, and return loss. However, with respect to the antenna’s radiation efficiency, size (compactness) and ease of fabrication, the conventional square microstrip patch antenna design is shown to be the better alternative of the two. In view of these obtained results, in future work, the objective would be focused on improving the rectenna performance, and practically validating this design. Finally, it is worth noting that for practical implementation, the antenna and rectifier circuit can be coupled via a SubMiniature version A (SMA) connector. The SMA connector is a 50-Ohm coaxial which utilizes a screw type coupling mechanism, and can work or frequencies even as high as 17 GHz. On the other hand, the patch antenna and rectifier circuit can be directly integrated on a single substrate without the need for SMA connectors. This could serve to avert losses associated with the SMA connector, and therefore provides a higher microwave to DC conversion efficiency.