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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"wideband antenna"”.
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Ultra-Wideband Antenna Characterization and Modeling
… methodology is presented for characterizing an antenna system both in the time and frequency domain with one set of parameters using a singularity expansion method representation. A minimal set of parameter modeling antenna systems using the Matrix-Pencil method has been demonstrated. It has …
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Directive ultra wideband antenna for medical applications
Since the acceptance of unlicensed band of Ultra-Wideband (UWB) technology in the range between 3.1 and 10.6 GHz, the realization of low-cost UWB wireless systems is considered a fundamental research goal both for military and commercial applications. The possible use and benefits of UWB technology …
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Compact planar wearable ultra wideband antenna for on-body applications
… sensors has given an interest in wearable antennas that are made for operation on the living bodies. Engineers have not stopped at creating a remarkable technology such as wearable systems, but also involved in understanding the interaction of electromagnetic (EM) waves with the body. …
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Ultra wideband antenna for microwave imaging using modified fractal structure
… of 7.5 GHz (from 3.1 GHz to 10.6 GHz) for ultra wideband application (UWB), UWB is rapidly advancing as a high data rate wireless technology. Moreover, there are more challenges in designing a UWB antenna than a narrow band antenna. A suitable UWB antenna should be capable of operating over an …
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Development of ultra wideband antenna array for human detection under debris
… was developed and after that, the use of ultra-wideband (UWB) radar was also the part of a study for some years. However, the limitations in such systems are penetration depth and resolution imaging, and there is a need for such a system which addresses both while designing the single antenna. …
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Analysis of Highly Coupled Wideband Antenna Arrays Using Scattering Parameter Network Models
Wideband phased arrays require very tight element spacing to permit wide angle scanning of the main beam over the wide bandwidth. The consequence of tight spacing is very high mutual coupling among the elements in the array. Previous efforts by Virginia Tech Antenna Group has shown that the strong …
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Wideband spectrum sensing using rapidly tuned antennas
… technology for cognitive radio is expeditious wideband spectrum sensing. A major challenge for implementing wideband spectrum sensors is fitting a wideband antenna within a given form factor. Scanning a narrowband antenna is an attractive alternative to using a wideband antenna in situations …
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Radio wave imaging using Ultra-Wide Band Spectrum Antennas for Near-Field Applications. Design, Development, and Measurements of Ultra-Wideband Antenna for Microwave Near-Field Imaging Applications by applying Optimisation Algorithms
The emergence of Ultra-wideband (UWB) technology application has yielded tremendous and vital impacts in the field of microwave wireless communications. These applications include military radar imaging, security screening, and tumour detection, especially for early detection of breast cancer. …
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Ultra-wideband antenna design for microwave imaging applications. Design, optimisation and development of ultra-wideband antennas for microwave near-field sensing tools, and study the matching and radiation purity of these antennas within near field environment.
… This thesis documents the development of antenna design for microwave imaging application such as breast cancer detection. The application is similar to the concept of Ground Penetrating Radar (GPR) but operating at higher frequency band. In these systems a short pulse is transmitted from …
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Single-band and Dual-band Beam Switching Systems and Offset-fed Beam Scanning Reflectarray
… for the various uses of the reflectarray. The wideband antenna element with a large phase variation range and a linear phase response is one of the solutions to increase the narrow bandwidth of the reflectarray. A four beam scanning reflectarray has been developed. It is the offset-fed …
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A Study of Techniques to Solve the Disparate Mesh Size Problem With an Application to Sinuous Antennas
… the fast multipole method (FMM) to a particular wideband antenna, the sinuous antenna. The essence of the problem is that a triangular patch mesh containing a wide range in patch sizes produces an ill-conditioned method of moments impedance matrix. Since the FMM algorithm relies on iterative …
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Characterization of Electron Number Density of Rocket Exhaust Plumes Through Microwave Transmissions
… includes the design and manufacture of ultra-wideband antenna arrays. The research estimates electron number density using methods exploiting signal processing techniques in time and frequency domain, but the data suggests that other dynamic elements influence delay and attenuation of the …
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Fundamental limits of wideband localization
… we investigate the localization performance of wideband networks and proposed a performance measure called the squared position error bound (SPEB) to characterize the localization accuracy. We derive the SPEB succinctly by applying the notion of equivalent Fisher information (EFI). The EFI …
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Modulation techniques for GPR system radargram
… object underground is dependent on the ultra-wideband antenna use. Based on this antenna type, the fractional bandwidth used by the GPR system is usually greater or equal to 1. On the other hand, the GPR system using fractional bandwidth less than 1 will produce unsmooth GPR radargram, as the …
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Archimedean spiral antenna embedded with frequency selective surface for wideband applications
… uniform unidirectional radiation pattern and wideband antenna ranging from 3.1 GHz to 10.6 GHz. An Archimedean spiral antenna is the most potential candidate in the above mentioned applications as the antenna meets most of the above requirements. However, the practical implementation of spiral …
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Antenna design using optimization techniques over various computaional electromagnetics. Antenna design structures using genetic algorithm, Particle Swarm and Firefly algorithms optimization methods applied on several electromagnetics numerical solutions and applications including antenna measurements and comparisons
… computation time, constraints put forward for antenna requirements and demand for large computer memory, are very common in the analysis due to the increased interests in tackling high-scale, more complex and higher-dimensional problems. On the other side, demands for even more accurate results …
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A Comprehensive Investigation of New Planar Wideband Antennas
Broadband wireless communications require wideband antennas to support large number of users and higher data rates. Desirable features of a wideband antenna are low-profile, dual-polarization and wide bandwidth in a compact size. Many existing wideband antennas are large in size and some have only …
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OPTIMAL ANTENNA DESIGNS FOR WIRELESS COMMUNICATION APPLICATIONS
Antennas design procedure, especially in portable devices, has been influenced by the growing demand for development of modern wireless communications. Hence, antennas that are wideband, compact, low profile, low cost, and easy to integrate into printed circuits are required. The research described …
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Synthesis of Ultra-Wideband Array Antennas
Acquisition of ultra-wideband signals by means of array antennas requires essentially frequency-independent radiation characteristics over the entire bandwidth of the signal in order to avoid distortions. Factors contributing to bandwidth limitation of arrays include array factor, radiation …
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Wideband Compact Antennas for Wireless Communication Applications
… devices to become physically smaller in size. Antenna size is obviously a major factor that limits miniaturization. In the past few years, new designs of low-profile antennas for handheld wireless devices have been developed. The major drawback of many low-profile antenna designs is their …
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