Bandwidth (signal processing)

About: Bandwidth (signal processing) is a research topic. Over the lifetime, 48550 publications have been published within this topic receiving 600741 citations. The topic is also known as: Bandwidth (signal processing) & bandwidth.

Method of creating and utilizing diversity in a multiple carrier communication system

Abstract: In many cellular systems, reusing spectrum bandwidth, creates problems in boundary regions between the cells and sectors where the signal strength received from adjacent base stations or adjacent sector transmissions of a single base station may be nearly equivalent. The invention creates a new type of diversity, referred to as multiple carrier diversity by utilizing multiple carriers, assigning different power levels to each carrier frequency at each base station, and/or offsetting sector antennas. The cell and/or sector coverage areas can be set so as to minimize or eliminate overlap between cell and/or sector boundary regions of different carrier frequencies. Mobile nodes traveling throughout the system can exploit multiple carrier diversity by detecting carriers and selecting to use a non-boundary carrier based on other system criteria in order to improve performance. Boundary carriers may, but need not be, identified and excluded from consideration for use by a wireless terminal.

Compact wide-band branch-line hybrids

Abstract: Wide-band branch-line couplers are designed and tested. The proposed couplers feature compact size on a single circuit layer structure without via-holes. For the broad-band property and cost effectiveness, we have designed a four-branch hybrid with mixed distributed and lumped distributed elements. Analysis on the equivalent circuits was performed carefully in order to obtain a sufficient bandwidth with reduced design area. The fabricated hybrids have the fractional bandwidth larger than 56% at the center frequency of 2 GHz. They also show size reduction up to 55.2% compared with the conventional design method.

SFDR-bandwidth limitations for high speed high resolution current steering CMOS D/A converters

Abstract: Although very high update rates are achieved in recent publications on high resolution D/A converters, the bottleneck in the design is to achieve a high spurious free output signal bandwidth. The influence of the dynamic output impedance on the chip performance has been analyzed and has been identified as an important limitation for the spurious free dynamic range (SFDR) of high resolution DAC's. Based on the presented analysis an optimized topology is proposed.

GaAs electro‐optic directional‐coupler switch

Abstract: We report the fabrication and testing of a GaAs electro‐optic directional‐coupler (EDC) switch in which the fraction of light coupled from one waveguide channel to the other can be controlled by an applied electric field Ninety‐five percent amplitude switching and a maximum extinction ratio of 13 dB have been observed in an EDC switch, having a minimum 3‐dB bandwidth of ≳100 MHz and a drive power per unit bandwidth of <180 μW/MHz

MEMS Reconfigurable Optimized E-Shaped Patch Antenna Design for Cognitive Radio

Abstract: Reconfigurable antennas offer attractive potential solutions to solve the challenging antenna problems related to cognitive radio systems using the ability to switch patterns, frequency, and polarization. In this paper, a novel frequency reconfigurable E-shaped patch design is proposed for possible applications in cognitive radio systems. This paper provides a methodology to design reconfigurable antennas with radio frequency microelectromechanical system (RF-MEMS) switches using particle swarm optimization, a nature-inspired optimization technique. By adding RF-MEMS switches to dynamically change the slot dimensions, one can achieve wide bandwidth which is nearly double the original E-shaped patch bandwidth. Utilizing an appropriate fitness function, an optimized design which works in the frequency range from 2 GHz to 3.2 GHz (50% impedance bandwidth at 2.4 GHz ) is obtained. RF-MEMS switch circuit models are incorporated into the optimization as they more effectively represent the actual switch effects. A prototype of the final optimized design is developed and measurements demonstrate good agreement with simulations.