In this article, we have theoretically demonstrated the mechanism of an active tractor beam for multiple fully immersed objects with additional abilities to yielding stable long distance levitation, a controlled rotation and a desired 3D trapping. This is demonstrated with a single optical setup by using two coaxial, or even non-coaxial, superimposed higher order monochromatic Bessel beams of reverse helical nature and different frequencies. The superimposed beams can possess periodic intensity variations both along and around the beam-axis due to a difference in longitudinal wave-numbers and beam orders, respectively. The difference in frequencies of the two laser beams makes the intensity pattern to move along and around the beam-axis in a continuous way without manual ramping of phase, which allows for bidirectional movement of completely immersed multiple particles. The condition for increasing or decreasing the dimension of binding regions is also proposed here to manipulate multiple immersed objects of different sizes under dipole approximation.
A Postbeamformer Interference Canceler (PIC) processes the signals derived from an array of antennas by forming two beams, a signal beam and an interference beam. This paper presents a method to study the performance of the PIC processor using the improved interference beam (IIB) for near field broadband directional sources. The technique presented in this paper extends the idea of previously published paper for far field beamforming to near field broadband beamforming and does not require the steering delays. A number of examples presented show the effectiveness, performance and capability of distance discrimination and robustness of the proposed broadband beamformer and compare with that using PIC with conventional interference beam (CIB) and with that using optimal element space processor (ESP).Index Terms-Broadband antenna arrays, Improved interference beam, Near field beamforming, PIC processors, Smart antennas.
In this paper, a novel analytical design technique is presented to implement a coupled-line wideband Wilkinson power divider (WPD). The configuration of the WPD is comprised of three distinct coupled-line and three isolation resistors. A comprehensive theoretical analysis is conducted to arrive at a set of completely new and rigorous design equations utilizing the dual-band behavior of commensurate transmission lines. Further, the corresponding S-parameters equations are also derived, which determine the wideband capability of the proposed WPD. To validate the proposed design concept, a prototype working at the resonance frequencies of 0.9 GHz and 1.8 GHz is designed and fabricated using 60 mils thick Rogers’ RO4003C substrate. The measured result of the fabricated prototype exhibits an excellent input return loss > 16.4 dB, output return loss > 15 dB, insertion loss < 3.30 dB and a remarkable isolation > 22 dB within the band and with a 15 dB and 10 dB references provide a fractional bandwidth of 110% and 141%, respectively.
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