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Title: Multi-path parameter and source localization for 2.4 GHz ISM radio band.
Creator: Hutasingh, Allapon., Florida Atlantic University, Helmken, Henry
Abstract/Description: Wireless communication has become a significant part of our life. Bluetooth(TM) Radio system is one example of wireless communication, Wireless Local Area Network (WLAN) is another example of wireless technology. Both of systems operate in the same frequency band, the Industrial Scientific Medical (ISM) band, which use a 2.4 GHz carrier frequency. According characteristic of system, multi-path effect are major concern for indoor propagation. A frequency sounding technique is introduced to...
Show moreWireless communication has become a significant part of our life. Bluetooth(TM) Radio system is one example of wireless communication, Wireless Local Area Network (WLAN) is another example of wireless technology. Both of systems operate in the same frequency band, the Industrial Scientific Medical (ISM) band, which use a 2.4 GHz carrier frequency. According characteristic of system, multi-path effect are major concern for indoor propagation. A frequency sounding technique is introduced to determine characteristics of the multi-path signal. However, multi-path can not be evaluated directly; some parameters are measured to determine the effect of multi-path. Angles of arrival can be used to facilitate the effect of multi-path signal. Using MatLab programming, Spatial Filter Periodogram (SPF) is introduced to estimate angles of arrival.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/12839
Subject Headings: Radio wave propagation, Bluetooth technology
Format: Document (PDF)

Title: An electromagnetic code evaluation in the 100 MHz to 1000 MHz region.
Creator: Casciato, Mark D., Florida Atlantic University, Helmken, Henry
Abstract/Description: For certain wavelength size objects, the frequency range between 100 MHz and 1000 MHz spans a transition region when using low frequency electromagnetic scattering codes based on Method of Moments (MoM) to high frequency codes based on Physical Theory of Diffraction (PTD) and ray tracing techniques. As the wavelength size of the object increased, MoM codes can require prohibitively long computational times and hence the more approximate high frequency codes become more attractive. The Ohio...
Show moreFor certain wavelength size objects, the frequency range between 100 MHz and 1000 MHz spans a transition region when using low frequency electromagnetic scattering codes based on Method of Moments (MoM) to high frequency codes based on Physical Theory of Diffraction (PTD) and ray tracing techniques. As the wavelength size of the object increased, MoM codes can require prohibitively long computational times and hence the more approximate high frequency codes become more attractive. The Ohio State Material Wire code (MATWRS) was selected as a representative MoM code for characterizing the transition region. XPATCH was selected as a representative high frequency code with ACAD used as the general modeling program. To evaluate these codes, a comparison of Radar Cross Section (RCS) predictions for simple PEC canonical shapes was made. Comparisons were made to both measured data where available and predictions generated by the McDonnell Douglas Body of Revolution (BOR) code.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15191
Subject Headings: Computer-aided design, Radar cross sections, Electromagnetic waves, Moments method (Statistics)
Format: Document (PDF)

Title: A software-hardware implementation of a real-time digital signal processing receiver for noise detection using a broadband microwave correlation technique.
Creator: Christodoulou, Christodoulos A., Florida Atlantic University, Helmken, Henry
Abstract/Description: In this research project the objective is to realize a software - hardware design implementation of a real time digital signal processing (DSP) radiometer - receiver for atmospheric noise temperature detection using the digital cross correlation technique. Atmospheric noise in the band of 20-30 GHz band is down-converted to 10.7 MHz IF and 3 MHz bandwidth in the form of statistical additive white gaussian noise which is used as the received signal by a digital signal processing broadband...
Show moreIn this research project the objective is to realize a software - hardware design implementation of a real time digital signal processing (DSP) radiometer - receiver for atmospheric noise temperature detection using the digital cross correlation technique. Atmospheric noise in the band of 20-30 GHz band is down-converted to 10.7 MHz IF and 3 MHz bandwidth in the form of statistical additive white gaussian noise which is used as the received signal by a digital signal processing broadband microwave radiometer based on the digital cross correlation technique. Living in a technological era, which is characterized as the era of data transmission and reception for RF-wireless communication systems, the theory of RF digital signal processing detection has applied to radar, ultrasound, and digital communications. Due to the need of high speed of data detection, much effort has gone into the design and development of sophisticated equipment to obtain such DSP detectors. Detection can also apply in seismic and big earthquake measurements by using geophones, nuclear testing, sonar and acoustic localizations, and even for oil excavations. Based on a statistical model and proposed design implementation, a basic DSP atmospheric noise temperature radiometer system is introduced and developed. The realization of the DSP Radiometer examines the noise characteristics (parameters) and their corresponding parameter values at the received input at the Antenna. It is essential to introduce the fundamental and statistical properties of the additive white gaussian noise, as well as the key-parameters which are used for the development of this real time design implementation. A design implementation of the proposed DSP atmospheric noise radiometer is discussed and developed via a statistical analysis. The statistical analysis utilizes the standard deviation, intermediate frequency, bandwidth, number of samples, and the temperature of the noise received signal at the antenna. Measurements and real time simulations in order to evaluate the noise temperature’s detectability in terms of system’s accuracy and performance of the noise random variable are also presented in this research work. The advantage of the digital cross correlation technique is examined and investigated.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/13290
Subject Headings: Signal processing--Digital techniques, Analog-to-digital converters, Radio--Receivers and reception
Format: Document (PDF)

Title: Ka-band radiometry in the Advanced Communications Technology Satellite (ACTS) system.
Creator: Bourgeois, Monique Jacqueline., Florida Atlantic University, Helmken, Henry
Abstract/Description: The Advanced Communications Technology Satellite propagation experiment was designed by NASA to study the effects of precipitation, primarily rain, on Ka frequency band signals. Two beacon signals, transmitted from the satellite, provide attenuation data that is recorded by a propagation terminal located in Tampa, Florida. The received beacon data contains a DC bias and diurnal effects and is therefore uncalibrated. Radiometers, centered at each beacon carrier frequency, are used to set the 0...
Show moreThe Advanced Communications Technology Satellite propagation experiment was designed by NASA to study the effects of precipitation, primarily rain, on Ka frequency band signals. Two beacon signals, transmitted from the satellite, provide attenuation data that is recorded by a propagation terminal located in Tampa, Florida. The received beacon data contains a DC bias and diurnal effects and is therefore uncalibrated. Radiometers, centered at each beacon carrier frequency, are used to set the 0 dB reference level for the beacon data, using constants determined through radiometer calibration techniques. The details of this process are examined using actual propagation data.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/15374
Subject Headings: Advanced Communications Technology Satellite, Artificial satellites in telecommunication, Radiometers
Format: Document (PDF)

Title: Effect of fading on the performance of a satellite communications link.
Creator: Karimi, Kaivan Abrahim., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Rain attenuation is the most dominant cause of signal degradation in satellite links operating at Ka-band. A review of rain measurements and effects of rain attenuation on satellite links will be discussed and will be followed by the latest developments in prediction and modeling of rain attenuation. Then an adaptive rain fade countermeasure based on the effective utilization of the channel capacity will be presented. In order to determine the outage rates both in terms of channel capacity...
Show moreRain attenuation is the most dominant cause of signal degradation in satellite links operating at Ka-band. A review of rain measurements and effects of rain attenuation on satellite links will be discussed and will be followed by the latest developments in prediction and modeling of rain attenuation. Then an adaptive rain fade countermeasure based on the effective utilization of the channel capacity will be presented. In order to determine the outage rates both in terms of channel capacity and bit error rate (BER), Manning's rain attenuation prediction model, based on the rain history of the transmitting and receiving stations, will be employed. Finally, a comprehensive statistical model for Land-Mobile Satellite Systems (LMSS) in the presence of rain attenuation will be proposed.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14975
Subject Headings: Artificial satellites in telecommunications, Rain and rainfall
Format: Document (PDF)

Title: Control system for a QPSK burst modem used for ACTS satellite testing.
Creator: Knight, Terence Robert., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: A test system was designed to determine the performance a QPSK satellite burst modem when using the Ka band link of the Advanced Communications Technology Satellite. Interface circuitry, largely based on the 22V10 programmable logic device, was designed to allow the modem to be controlled by a personal computer. Communication between the interface and the computer was accomplished through the computer's parallel port. TDMA frame timing was automatically controlled by the interface. A C...
Show moreA test system was designed to determine the performance a QPSK satellite burst modem when using the Ka band link of the Advanced Communications Technology Satellite. Interface circuitry, largely based on the 22V10 programmable logic device, was designed to allow the modem to be controlled by a personal computer. Communication between the interface and the computer was accomplished through the computer's parallel port. TDMA frame timing was automatically controlled by the interface. A C language program provided operator control of the interface itself. Tests using this system showed that a severe night-time fading problem is experienced at the FAU receiver site. Very low error rates were recorded by this system in a loop-back transmission at the NASA satellite control terminal.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15139
Subject Headings: Advanced Communications Technology Satellite, Artificial satellites in telecommunication, Digital communications
Format: Document (PDF)

Title: Diversity performance of DS-CDMA systems in multipath fading channels.
Creator: Efthymoglou, George P., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: In this dissertation, new semi-analytical expressions for the diversity bit error rate performance of asynchronous direct sequence-code division multiple access (DS-CDMA) systems in multipath fading channels are derived. Also, the PN acquisition time of a DS system with offset frequency periods greater than the code period in a AWGN channel is measured via laboratory experiments. In Part I we consider DS-CDMA systems operating in a cellular environment with multipath reception. Multipath...
Show moreIn this dissertation, new semi-analytical expressions for the diversity bit error rate performance of asynchronous direct sequence-code division multiple access (DS-CDMA) systems in multipath fading channels are derived. Also, the PN acquisition time of a DS system with offset frequency periods greater than the code period in a AWGN channel is measured via laboratory experiments. In Part I we consider DS-CDMA systems operating in a cellular environment with multipath reception. Multipath propagation is exploited through the use of RAKE receivers. Coherent, differentially coherent and noncoherent binary demodulation schemes are considered. The multiple access interference is modeled as AWGN, conditioned on the fading statistics of the received signal. The mobile radio channel introduces selective fading, and is modeled as a tapped delay line. The amplitude of each resolvable path is statistically described by the Nakagami distribution, which is a general solution to the random vector problem that causes rapid fading. However, we assume independent but nonidentical fading along the RAKE branches. Therefore our analysis supports unequal mean powers and different amount of fading in the multipath components combined by the receiver. Also, the results can be easily extended to account for diversity from multiple antennas or coding in the generalized Nakagami multipath fading environment. In Part II we consider a land mobile satellite channel. First, a laboratory experiment is setup to evaluate the PN acquisition performance of a digital IF receiver in a AWGN channel with large Doppler offset. The digital conversion receiver uses the inherent aliasing property of sampling to realize the baseband conversion using a single analog-to-digital converter. Thereafter, digital signal processing on the I and Q samples enable for design trade-offs in the acquisition of the PN code with Doppler periods greater than the code period. Two code phase selection criterions, namely the maximum criterion and the threshold crossing criterion, are investigated and their acquisition time is measured for different frequency offsets and input IF signal to noise ratios. We also derive semi-analytical expressions for the BER performance of coherent and differentially coherent systems operating in a mobile satellite channel. In this case the channel is modeled as a multipath nonselective channel, but diversity gain can still be obtained through path diversity. This is the scenario when a signal is transmitted to all satellites in view and the received replicas are independently demodulated and combined at the receiver. Our analysis extends previous results to the case of unequal mean powers and Rice factors in the combined signals; a valid assumption if we consider that the satellites are in view at different elevation angles. Furthermore, the effect of imperfect power control in such mobile satellite DS-CDMA systems is also considered.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/12516
Subject Headings: Mobile communication systems, Wireless communication systems, Radio wave propagation
Format: Document (PDF)

Title: Optimizing body-proximate telecommunications devices in direct and multipath propagation.
Creator: Siwiak, Kazimierz., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Body-proximate telecommunications devices are examined in both direct and multipath propagation. The study begins with a characterization of standard field strength sensitivity measurement methods for body-proximate telecommunications devices. Original measurements on a group of anthropometrically diverse people reveal that human adults, in a standard pose, are remarkably similar with respect to belt worn sensitivity performance, which motivates and justifies the use of an existing and a...
Show moreBody-proximate telecommunications devices are examined in both direct and multipath propagation. The study begins with a characterization of standard field strength sensitivity measurement methods for body-proximate telecommunications devices. Original measurements on a group of anthropometrically diverse people reveal that human adults, in a standard pose, are remarkably similar with respect to belt worn sensitivity performance, which motivates and justifies the use of an existing and a newly introduced light weight simulated human body device for testing, analysis and optimization of body worn telecommunications devices. Standard measurement methods using standard open air test ranges are established and validated by international transfers of measurements. The study extends to optimization of telecommunications devices in multipath, and particularly to the diversity reception of signals. A novel signal simulation model is introduced which includes multipath and shadowing, and is validated against both theoretical statistics and measurements. The signal simulation model is extended to characterize polarization randomization and cross-coupling based on an urban generalization of building height to street width ratio. The model is used to analyze measurements of polarization randomization of signals originating from an airborne transmitter flying a path whose geometry is consistent with low earth orbiting communications satellites.
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Date Issued: 1998
PURL: http://purl.flvc.org/fcla/dt/12570
Subject Headings: Telecommunication--Equipment and supplies, Radio wave propagation, Telecommunication systems
Format: Document (PDF)

Title: Optimally polarized monopulse signals for target parameter estimation in clutter.
Creator: Kang, Eyung W., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The probability density function of the target boresight angle estimate of an amplitude comparison monopulse radar system is presented when the target in flight is obscured by dipole chaff, precipitation, or sea clutter. A maximum likelihood analysis is made to determine the form of the angle estimate in clutter plus receiver noise. The biasedness of the estimate, and the variance of that estimate is shown as a function of signal-to-clutter-plus-noise, SCNR. In order to improve the SCNR, the...
Show moreThe probability density function of the target boresight angle estimate of an amplitude comparison monopulse radar system is presented when the target in flight is obscured by dipole chaff, precipitation, or sea clutter. A maximum likelihood analysis is made to determine the form of the angle estimate in clutter plus receiver noise. The biasedness of the estimate, and the variance of that estimate is shown as a function of signal-to-clutter-plus-noise, SCNR. In order to improve the SCNR, the optimum transmit and receive polarization vectors for a given target and clutter scattering matrices are introduced. The optimum polarization vectors yield the maximum signal-to-clutter power ratio for a given scenario. The target model is a right circular cylinder with a hemispheric nose cone and the control surfaces attached. Included are the performance analysis of suboptimal polarization vector pair operations when the complex antenna cluster construction for the polarization diversity or agility is undersirable due to cost or the space restriction.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/11917
Subject Headings: Monopulse radar, Radar targets
Format: Document (PDF)

Title: Propagation on satellite path in Ka-band.
Creator: Koro, Zlata., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted need for analyzing effects of different propagation phenomena. Since the wavelength of radiowaves is comparable with the size of rain drops, rain attenuation is the dominant propagation impairment at Ka frequencies. In addition, other impairments such as gaseous absorption, cloud and fog attenuation, tropospheric refractive effects, as well as depolarization become increasingly important...
Show moreThe rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted need for analyzing effects of different propagation phenomena. Since the wavelength of radiowaves is comparable with the size of rain drops, rain attenuation is the dominant propagation impairment at Ka frequencies. In addition, other impairments such as gaseous absorption, cloud and fog attenuation, tropospheric refractive effects, as well as depolarization become increasingly important with increasing operating frequency. Theoretical background of radiowave propagation principles, rain systems and gases in the atmosphere are presented to insure comprehension of propagation effects on space communication in Ka-band. Models for predicting rain attenuation and other propagation impairments along Earth-satellite path are provided in order to simplify design of communication systems. Propagation phenomena are explained on example of three propagation experiments performed in U.S., Europe and Japan. Whenever possible, mitigation techniques to overcome severe attenuations are introduced.
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Date Issued: 1998
PURL: http://purl.flvc.org/fcla/dt/15529
Subject Headings: Artificial satellites in telecommunication, Radio wave propagation, Astronautics--Communication systems, Astronautics in meteorology
Format: Document (PDF)

Title: Radar cross section of an open-ended rectangular waveguide cavity: A massively parallel implementation applied to high-resolution radar cross section imaging.
Creator: Vann, Laura Dominick., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: This thesis is concerned with adapting a sequential code that calculates the Radar Cross Section (RCS) of an open-ended rectangular waveguide cavity to a massively parallel computational platform. The primary motivation for doing this is to obtain wideband data over a large range of incident angles in order to generate a two-dimensional radar cross section image. Images generated from measured and computed data will be compared to evaluate program performance. The computer used in this...
Show moreThis thesis is concerned with adapting a sequential code that calculates the Radar Cross Section (RCS) of an open-ended rectangular waveguide cavity to a massively parallel computational platform. The primary motivation for doing this is to obtain wideband data over a large range of incident angles in order to generate a two-dimensional radar cross section image. Images generated from measured and computed data will be compared to evaluate program performance. The computer used in this implementation is a MasPar MP-1 single instruction, multiple data massively parallel computer consisting of 4,096 processors arranged in a two-dimensional mesh. The algorithm uses the mode matching method of analysis to match fields over the cavity aperture to obtain an expression for the scattered far field.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14984
Subject Headings: Radar cross sections, Algorithms--Data processing, Imaging systems
Format: Document (PDF)

Title: T1 Satcom interface used in conjunction with ACTS VSAT terminal.
Creator: Robinson, Lancelot George., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: To observe the effects of satellite transmission on video compression technology designed at FAU's Imaging Systems Lab; an interface was designed to accept data directly from a video encoder or a 16 GByte RAID storage device. The design uses a Xilinx XC4005E field programmable gate array. The interface connects to a high speed enhanced parallel port at the computer backplane. Data stored via the interface on the computer; is transferred at a T1 rate through the ACTS T1-VSAT satellite link. In...
Show moreTo observe the effects of satellite transmission on video compression technology designed at FAU's Imaging Systems Lab; an interface was designed to accept data directly from a video encoder or a 16 GByte RAID storage device. The design uses a Xilinx XC4005E field programmable gate array. The interface connects to a high speed enhanced parallel port at the computer backplane. Data stored via the interface on the computer; is transferred at a T1 rate through the ACTS T1-VSAT satellite link. In loop-back mode the data is stored, then evaluated.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/15430
Subject Headings: Artificial satellites in telecommunication, VSATs (Telecommunication), Video compression
Format: Document (PDF)

Title: A maximum entropy bandwidth extrapolation technique using wavelet subspaces.
Creator: Vann, Laura Dominick., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: This dissertation is concerned with the development of a bandwidth extrapolation technique that performs maximum entropy estimations over wavelet subspaces. Bandwidth extrapolation techniques have been used in radar applications to improve range and cross range resolution of radar cross section (RCS) images. Comparisons are made of the performance of conventional maximum entropy estimation to maximum entropy estimation over wavelet subspaces. A least squares prediction error measure is used...
Show moreThis dissertation is concerned with the development of a bandwidth extrapolation technique that performs maximum entropy estimations over wavelet subspaces. Bandwidth extrapolation techniques have been used in radar applications to improve range and cross range resolution of radar cross section (RCS) images. Comparisons are made of the performance of conventional maximum entropy estimation to maximum entropy estimation over wavelet subspaces. A least squares prediction error measure is used to compare original measured RCS data to extrapolated data. Then a relative error is defined as the ratio of prediction error using conventional maximum entropy to prediction error using maximum entropy over wavelet subspaces. Application of the bandwidth extrapolation technique is to measured RCS data of two objects. The first object consists of two 3/8" diameter conducting spheres placed 4" apart. Measurements used are for vertical polarization and 0 degree aspect angle covering a frequency range of 8.0 to 12.3827 GHz. The second object is a 1.6 meter aluminum cone. Measurements used are for vertical polarization and 0 degree aspect angle (nose on) covering a frequency range of 4.64 to 18.00 GHz. Results are shown for extrapolate measured data plus the original data with Gaussian white noise added to noise ratios of 25 dB, 20 dB, 15 dB, and 10 dB.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/12531
Subject Headings: Maximum entropy method, Wavelets (Mathematics), Radar cross sections
Format: Document (PDF)

Title: Electromagnetic scattering from a periodic array of open-ended rectangular waveguide apertures.
Creator: Bohning, Terry., Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: In this dissertation, the Radar Cross Section (RCS) of a large periodic array of rectangular open-ended waveguide apertures is determined numerically using several methods. The aperture boundaries are presumed to be Perfect Electrical Conductors (PEC). Although the problems of radiation from such a waveguide array and of aperture array scattering have been treated in the literature, the problem of scattering from an array of waveguide apertures does not appear to have been solved before....
Show moreIn this dissertation, the Radar Cross Section (RCS) of a large periodic array of rectangular open-ended waveguide apertures is determined numerically using several methods. The aperture boundaries are presumed to be Perfect Electrical Conductors (PEC). Although the problems of radiation from such a waveguide array and of aperture array scattering have been treated in the literature, the problem of scattering from an array of waveguide apertures does not appear to have been solved before. Considering the case of an array with constituent guides of semi-infinite length, the RCS is computed by several numerical methods based on the Integral Equation (IE) method, a least-squared error minimization technique referred to as Squared Field Error (SFE) method, direct solution of a surface integral equation, the Spectral Domain Method, and by using waveguide modes computed via the Finite Element Method (FEM). The case of finite-length guides is also treated using the IE and SFE methods. The results of these methods are compared with experimental data obtained from an outdoor RCS range. In order to simulate the semi-infinite case, the finite-length waveguides were terminated with radar absorbing foam so that nearly all reflection occurred at the apertures impinged upon by the incident plane wave. For all the methods cited, the infinite array approximation (cell-to-cell field periodicity except for a linear progressive interelement phase shift) is assumed to hold. A derivation of Floquet modes which implement this "phase-periodic" boundary condition is provided in an appendix, where an incidental discussion concerning the scalar and vector Laplacian operators is also furnished. A description of the structure and user interface of the software which has been written to implement the various methods is also given. The purposes of major subroutines and data structures are also delineated and several control-flow diagrams are included. As a foundation to extend the present work to analysis of the electromagnetic fields within an absorber coated PEC waveguide, a brief survey and a discussion of related work is provided.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/12308
Subject Headings: Wave guides, Electromagnetic fields
Format: Document (PDF)

Title: Estimation of atmospheric gaseous absorption using surface and radiosonde meteorological measurements.
Creator: Pollard, Ritsuko Hamahata, Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: For radiowave propagation on earth-space communication links at high frequencies such as Ka-band, the effect of atmospheric gaseous absorption (mainly due to oxygen and water vapor) is the primary cause of attenuation. This thesis examines the applicability of the surface based Crane's model currently employed by the Advanced Communications Technology Satellite (ACTS) propagation experiment for estimation of attenuation due to atmospheric gaseous absorption (AGA), developed for Oklahoma, to...
Show moreFor radiowave propagation on earth-space communication links at high frequencies such as Ka-band, the effect of atmospheric gaseous absorption (mainly due to oxygen and water vapor) is the primary cause of attenuation. This thesis examines the applicability of the surface based Crane's model currently employed by the Advanced Communications Technology Satellite (ACTS) propagation experiment for estimation of attenuation due to atmospheric gaseous absorption (AGA), developed for Oklahoma, to sub-tropical climate regions such as Florida. The Microwave Propagation Model is used as a basis of comparison since it uses the direct atmospheric measurements (temperature, relative humidity, and pressure) made at different levels of the atmosphere with radiosonde instrumentation. The AGA was individually examined for oxygen and water vapor. Finally, accuracy of the Crane's model was verified by computing the attenuation results using real acquired data for both models and comparing their results in various ways for several months.
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Date Issued: 1998
PURL: http://purl.flvc.org/fcla/dt/15602
Subject Headings: Tropospheric radio wave propagation, Meteorological instruments
Format: Document (PDF)

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)

Title: EM polarization measurement campaign and its applications.
Creator: Pollard, Ritsuko Hamahata, Florida Atlantic University, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Due to a continuous growth of demand in voice and data communications for wireless systems, there is an ongoing challenge to design improved radiowave communication links. Polarization is one of the key properties of electromagnetic waves used in wireless communication and is the least studied in a scattering environment. A detailed understanding of how signals become de-polarized can improve the propagation models and can lead to more accurate propagation predictions and possibly new...
Show moreDue to a continuous growth of demand in voice and data communications for wireless systems, there is an ongoing challenge to design improved radiowave communication links. Polarization is one of the key properties of electromagnetic waves used in wireless communication and is the least studied in a scattering environment. A detailed understanding of how signals become de-polarized can improve the propagation models and can lead to more accurate propagation predictions and possibly new applications in the use of polarization. Potential beneficiaries of a system design using multi-dimensional polarization constellations to provide maximum polarization separation might include inter-satellite links, WLAN, LEO satellites [BSPP92] [IPLJ81] [SIKA98] and other systems operating in an environment where depolarization is insignificant. To examine the applicability of polarization in wireless communication systems, polarization field measurements were conducted, and the results and analysis are presented in this dissertation. Based on the analysis, a statistical model that characterizes polarization in relation to Poincare sphere is developed and presented. Design and implementation of an N-constellation diversity scheme that provides maximum polarization separation distance is presented. Furthermore, a decision-making algorithm is utilized for detection of the received electric field that selects the minimum Euclidian distance between the transmitter and receivers in Stokes space. The scenario is simulated for an N-constellation scheme for N = 2, 3, 4 based on the design scheme utilizing the developed statistical model and decision-making algorithm and is used to evaluate the detectability and performance comparison for various values of standard deviations.
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Date Issued: 2004
PURL: http://purl.flvc.org/fau/fd/FADT12089
Subject Headings: Electromagnetic waves--Polarization, Wireless communication systems
Format: Document (PDF)

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)

Title: Synchronization in digital wireless radio receivers.
Creator: Nezami, Mohamed Khalid., Florida Atlantic University, Sudhakar, Raghavan, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Time Division Multiple Access (TDMA) architecture is an established technology for digital cellular, personal and satellite communications, as it supports variable data rate transmission and simplified receiver design. Due to transmission bandwidth restrictions, increasing user demands and the necessity to operate at lower signal-to-noise ratio (SNR), the TDMA systems employ high order modulation schemes such as M-ary Quadrature Amplitude Modulation (M-QAM) and burst transmission. Use of such...
Show moreTime Division Multiple Access (TDMA) architecture is an established technology for digital cellular, personal and satellite communications, as it supports variable data rate transmission and simplified receiver design. Due to transmission bandwidth restrictions, increasing user demands and the necessity to operate at lower signal-to-noise ratio (SNR), the TDMA systems employ high order modulation schemes such as M-ary Quadrature Amplitude Modulation (M-QAM) and burst transmission. Use of such techniques in low SNR fading channels causes degradations of carrier frequency error, phase rotation error, and symbol timing jitter. To compensate for the severe degradation due to additive white Gaussian noise (AWGN) and channel impairments, precise and robust synchronization algorithms are required. This dissertation deals with the synchronization techniques for TDMA receivers using short burst mode transmission with emphasis on preamble-less feedforward synchronization schemes. The objective is to develop new algorithms for symbol timing, carrier frequency offset acquisition, and carrier phase tracking using preamble-less synchronization techniques. To this end, the currently existing synchronization algorithms are surveyed and analyzed. The performance evaluation of the developed algorithms is conducted through Monte-Carlo simulations and theoretical analyses. The statistical properties of the proposed algorithms in AWGN and fading channels are evaluated in terms of the mean and variance of the estimated synchronization errors and their Cramer-Rao lower bounds. Based on the investigation of currently employed feedforward symbol timing algorithms, two new symbol timing recovery schemes are proposed for 16-QAM land mobile signals operating in fading channels. Both schemes achieve better performance in fading channels compared to their existing counterparts without increasing the complexity of the receiver implementation. Further, based on the analysis of currently employed carrier offset and carrier phase recovery algorithms, two new algorithms are proposed for carrier acquisition and carrier tracking of mobile satellite systems utilizing short TDMA bursts with large frequency offsets. The proposed algorithms overcome some of the conventional problems associated with currently employed carrier recovery schemes in terms of capture range, speed of convergence, and stability.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/11947
Subject Headings: Radio--Receivers and reception, Digital communications, Time division multiple access
Format: Document (PDF)

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Radio--Receivers and reception (2)	+ -
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Florida Atlantic University (19)	+ -
Helmken, Henry (19)	+ -
College of Engineering and Computer Science (15)	+ -
Department of Computer and Electrical Engineering and Computer Science (15)	+ -
Pollard, Ritsuko Hamahata (2)	+ -

Vann, Laura Dominick. (2)	+ -
Bohning, Terry. (1)	+ -
Bourgeois, Monique Jacqueline. (1)	+ -
Casciato, Mark D. (1)	+ -
Christodoulou, Christodoulos A. (1)	+ -
Efthymoglou, George P. (1)	+ -
Hutasingh, Allapon. (1)	+ -
Kang, Eyung W. (1)	+ -
Karimi, Kaivan Abrahim. (1)	+ -
Knight, Terence Robert. (1)	+ -
Koro, Zlata. (1)	+ -
Nezami, Mohamed Khalid. (1)	+ -
Overton, David Hill. (1)	+ -
Ponce de Leon, Lorenzo Angel. (1)	+ -
Robinson, Lancelot George. (1)	+ -
Siwiak, Kazimierz. (1)	+ -
Sudhakar, Raghavan (1)	+ -

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