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Modeling and measurement of the response of small antennas near multilayered two or three-dimensional dielectric bodies
Title
Modeling and measurement of the response of small antennas near multilayered two or three-dimensional dielectric bodies.
Creator
Ponce de Leon, Lorenzo Angel., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
A theory of the circular loop antenna constructed from finite conductivity wire is developed via a Fourier series expansion of the currents in the loop. Models for a family of small loop antennas are also presented. A new high sensitivity and selectivity heterodyne fiber optic based electromagnetic field detector is developed compatible with open antenna range measurements made at low signal levels and in the presence of strong interfering signals. A new analytical solution pertaining to the...
Show moreA theory of the circular loop antenna constructed from finite conductivity wire is developed via a Fourier series expansion of the currents in the loop. Models for a family of small loop antennas are also presented. A new high sensitivity and selectivity heterodyne fiber optic based electromagnetic field detector is developed compatible with open antenna range measurements made at low signal levels and in the presence of strong interfering signals. A new analytical solution pertaining to the response of a disk loaded dipole antenna representing a dipole configured on a lossy dielectric medium is developed using a field compensation theorem and a geometrical theory of diffraction. The multipole expansions for the scattered fields of a multilayered infinite cylinder illuminated by oblique incidence plane wave are formulated and programmed for numerical analysis. The response of cylinders with constitutive parameters reflecting those used in human phantoms are calculated. The response of a small antenna proximal to a multilayered cylinder is analyzed. The scattered fields from multilayered bodies are coupled to a small wire antenna using a combined methods induced electromagnetic force (EMF) technique. New results concerning the response of a loop antenna near a multilayered body obtained via a zero and first phase current model are presented. The new technique is applied in the analysis of human phantoms tested in an open field antenna range. Validation of the theory of multilayered human phantoms with measurements using the new detector is demonstrated.
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Date Issued
1992
PURL
http://purl.flvc.org/fcla/dt/12294
Subject Headings
Antennas (Electronics)
Format
Document (PDF)
Studies on transreceive diversity schemes (including "polarization-sense" antenna diversity) for wireless communication systems
Title
Studies on transreceive diversity schemes (including "polarization-sense" antenna diversity) for wireless communication systems.
Creator
Preedalumpabut, Wichean., Florida Atlantic University, Neelakanta, Perambur S., Morgera, Salvatore D., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
The research addressed in this study and deliberated in the dissertation is broadly tied to finding hybrid methods of diversity compatible for modern wireless applications. The hybrid strategy advocated thereof involves a combined use of space- (antenna and polarization), frequency-, and time-diversity schemes in a judicious manner so as to realize a desirable BER versus Eb/No performance across RF links that face multipath and other unwanted EM artifacts. The underlying reason for the hybrid...
Show moreThe research addressed in this study and deliberated in the dissertation is broadly tied to finding hybrid methods of diversity compatible for modern wireless applications. The hybrid strategy advocated thereof involves a combined use of space- (antenna and polarization), frequency-, and time-diversity schemes in a judicious manner so as to realize a desirable BER versus Eb/No performance across RF links that face multipath and other unwanted EM artifacts. The underlying reason for the hybrid scheme as above is to replace multiple-antenna based transreceive diversity. Such multiple antennas would otherwise require large base station real estate and may not be compatible for hand-held (space-constrained) RF units. On the contrary, use of hybrid schemes would restrict multiple number of antennas and conserves the space. After analyzing a set of plausible techniques of hybrid diversity compatible for modern wireless techniques, a focused study has been done on polarization-sense (PS) antenna diversity scheme. Its fruitful application for indoor systems (like Bluetooth(TM)/ZigBee(TM)) against multipath effects is demonstrated via simulation and experimental studies. Further, the PS-antenna diversity is shown to offer improved BER versus Eb/N o performance in pilot channels used in CDMA2000 systems. Also, such PS-diversity is shown to help improving the GPS receiver performance under RFI/jamming environment. The technique and heuristics proposed towards the PS-antenna diversity scheme imply novel and hitherto unexplored efforts in wireless communications. Lastly the dissertation concludes summarizing the results and offers open-questions for further studies.
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Date Issued
2004
PURL
http://purl.flvc.org/fcla/dt/12104
Subject Headings
Wireless communication systems, Antennas (Electronics)
Format
Document (PDF)
Comparison of computer modelled monopole element with both 120 buried ground radials and 4 elevated ground radials at various heights using NEC-81 versus measured field data in the standard AM broadcast band at 1 MHz
Title
Comparison of computer modelled monopole element with both 120 buried ground radials and 4 elevated ground radials at various heights using NEC-81 versus measured field data in the standard AM broadcast band at 1 MHz.
Creator
Overton, David Hill., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
It has been proposed that the use of a small number of ground radials elevated above the surface of the earth can yield similar or actually better radiated performance than a larger number (typically 120) of buried ground radials in the case of a monopole element used in the standard AM broadcast band. This proposal is based on the results of numerous computer modelling. The author knows of no A-B field tests compared to the computed data. A case study is performed at 1 MHz (the center of the...
Show moreIt has been proposed that the use of a small number of ground radials elevated above the surface of the earth can yield similar or actually better radiated performance than a larger number (typically 120) of buried ground radials in the case of a monopole element used in the standard AM broadcast band. This proposal is based on the results of numerous computer modelling. The author knows of no A-B field tests compared to the computed data. A case study is performed at 1 MHz (the center of the standard AM broadcast band) using the NEC-81 computer program modelling both the elevated and buried ground radial scenarios and comparing the findings to the identical measured data. Tower impedances, currents in both the tower legs and along the elevated radials, and radiated fields along one radial and in between two radials at 1 km are presented.
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Date Issued
1990
PURL
http://purl.flvc.org/fcla/dt/14655
Subject Headings
Radio--Antennas, Antennas (Electronics)--Models, Radio frequency modulation
Format
Document (PDF)
Effects of Adaptive Antenna Array Beamforming and Power Management with Antenna Element Selection
Title
Effects of Adaptive Antenna Array Beamforming and Power Management with Antenna Element Selection.
Creator
Abazari Aghdam, Sajjad, Bagby, Jonathan S., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
This research is the array processing help wireless communication techniques to increase the signal accuracy. This technique has an important part of prevalent applications. The wireless communication system, radar, and sonar. Beamforming is one of methods in array processing that filters signals based on their capture time at each element in an array of antennas spatially. Numerous studies in adaptive array processing have been proposed in the last several decades, which are divided in two...
Show moreThis research is the array processing help wireless communication techniques to increase the signal accuracy. This technique has an important part of prevalent applications. The wireless communication system, radar, and sonar. Beamforming is one of methods in array processing that filters signals based on their capture time at each element in an array of antennas spatially. Numerous studies in adaptive array processing have been proposed in the last several decades, which are divided in two parts. The first one related to non-adaptive beamforming techniques and the next one related to digitally adaptive Beamforming methods. The trade-off between computational complexity and performance make them different. In this thesis, we concentrate on the expansion of array processing algorithms in both non-adaptive and adaptive ones with application of beamforming in 4G mobile antenna and radar systems. The conventional and generalized side-lobe canceller (GSC) structures beamforming algorithms were employed with a phase array antenna that changed the phase of arrivals in array antenna with common phased array structure antennas. An eight-element uniform linear array (ULA), consisting of di-pole antennas, represented as the antenna array. An anechoic chamber measures the operation of beamforming algorithms performance. An extended modified Kaiser weighting function is proposed to make a semi-adaptive structure in phased array beamforming. This technique is extended to low complexity functions like hyperbolic cosine and exponential functions. Furthermore, these algorithms are used in GSC beamforming. The side-lobe levels were so lower than other algorithms in conventional beamforming around -10 dB. On the other hand, a uniform linear arrays for smart antenna purposes designed to utilize in implementing and testing the proposed algorithms. In this thesis, performance of smart antenna with rectangular aperture coupled microstrip linear array which experimental investigations carried out for obtaining X-band operation of rectangular microstrip antenna by using aperture coupled feeding technique. Frequency range set at approximately 8.6 to 10.9 GHz, by incorporating frequency range of the antenna resonates for single wideband with an impedance bandwidth of 23%. The enhancement of impedance bandwidth and gain does not affect the nature of broadside radiation characteristics. This thesis describes the design, operation, and realization of the beamforming such as Sidelobe level (SLL) control and null forming array antenna are examined with the prototype. An antenna radiation pattern beam maximum can be simultaneously placed towards the intended user or Signal of interest (SOl), and, ideally nulls can be positioned towards directions of interfering signals or signals not of interest (SNOIs). Finally, we focused on the adaptive digitally algorithms in compact antenna that faces with mutual coupling. The variable step-size normalized lease mean square (VS-NLMS) algorithm is implemented in beamforming. This algorithm utilizes continuous adaptation. The weights are attuned that the final weight vector to the most satisfied result. The gradient vector can be achieved by iterative beamforming algorithm from the available data. This algorithm is compared with LMS, NLMS, VSS-NLMS algorithms, it is determined that the VSS-NLMS algorithm is better performance to other algorithms. Finally, we introduced novel adaptive IP-NNLMS beamformer. This beamformer reaches to faster convergence and lower error floor than the previous adaptive beamformers even at low SNRs in presence of mutual coupling. The experimental results verified the simulation results that the proposed technique has better performance than other algorithms in various situations.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004789, http://purl.flvc.org/fau/fd/FA00004789
Subject Headings
Global system for mobile communications., Long-Term Evolution (Telecommunications), Wireless communication systems., Antennas (Electronics), Antenna arrays., Array processors., Time-domain analysis.
Format
Document (PDF)