Matching Items (32)
Description
This thesis details the design process of a variable gain amplifier (VGA) based circuit which maintains a consistent output power over a wide range of input power signals. This effect is achieved by using power detection circuitry to adjust the gain of the VGA based on the current input power so that it is amplifier to a set power level. The paper details the theory behind this solutions as well as the design process which includes both simulations and physical testing of the actual circuit. It also analyses results of these tests and gives suggestions as to what could be done to further improve the design. The VGA based constant output power solution was designed as a section of a larger circuit which was developed as part of a senior capstone project, which is also briefly described in the paper.
ContributorsMeyer, Sheldon (Author) / Aberle, James (Thesis director) / Chakraborty, Partha (Committee member) / Electrical Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
The honors thesis presented in this document describes an extension to an electrical engineering capstone project whose scope is to develop the receiver electronics for an RF interrogator. The RF interrogator functions by detecting the change in resonant frequency of (i.e, frequency of maximum backscatter from) a target resulting from an environmental input. The general idea of this honors project was to design three frequency selective surfaces that would act as surrogate backscattering or reflecting targets that each contains a distinct frequency response. Using 3-D electromagnetic simulation software, three surrogate targets exhibiting bandpass frequency responses at distinct frequencies were designed and presented in this thesis.
ContributorsSisk, Ryan Derek (Author) / Aberle, James (Thesis director) / Chakraborty, Partha (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Modern communication systems call for state-of-the-art links that offer almost idealistic performance. This requirement had pushed the technological world to pursue communication in frequency bands that were almost incomprehensible back when the first series of cordless cellphones were invented. These requirements have impacted everything from civilian requirements, space, medical diagnostics to defense technologies and have ushered in a new era of advancements. This work presents a new and novel approach towards improving the conventional phased array systems. The Intelligent Phase Shifter (IPS) offers phase tracking and discrimination solutions that currently plague High-Frequency wireless systems. The proposed system is implemented on (CMOS) process node to better scalability and reduce the overall power dissipated. A tracking system can discern Radio Frequency (RF) Signals’ phase characteristics using a double-balanced mixer. A locally generated reference signal is then matched to the phase of the incoming receiver using a fully modular yet continuous complete 360ᵒ phase shifter that alters the phase of the local reference and matches the phase with that of an incoming RF reference. The tracking is generally two control voltages that carry In-phase and Quadrature-phase information. These control signals offer the capability of controlling similar devices when placed in an array and eliminating any ambiguity that might occur due to in-band interference.
ContributorsLakshminarasimhaiah Rajendra, Yashas (Author) / Zeinolabedinzadeh, Saeed (Thesis advisor) / Trichopoulos, Georgios (Committee member) / Aberle, James (Committee member) / Arizona State University (Publisher)
Created2021
Description
This honors thesis explores the potential use of LoRa technology for detecting moisture in a diaper. Tests of both onboard and external humidity sensors coupled with LoRa transmission are incredibly promising. The potential scale of the final device also shows much promise, measuring smaller than a U.S. dime. However, the estimated cost for producing these proof-of-concept units in bulk is $19.41 per unit. While this is believed to be a pessimistic estimate of the price, the cost of production remains too high regardless for large-scale implementation. The thesis concludes by emphasizing the need for further research and development to optimize the design and reduce the cost of production. Despite the limitations imposed by price, the idea of using LoRa in detecting moisture in a diaper remains intriguing and promising, however, RFID technology has many advantages, such as size, cost, and passive power features.
ContributorsBetlaf, Garrett (Author) / Aberle, James (Thesis director) / McDonald, James (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2023-05
Description
Satellite communications employs circular polarization (CP) to circumvent thewell-known phenomenon known as Faraday Rotation, where the ionosphere rotates the
horizontal and vertical polarization components resulting in signal degradation especially
at lower frequencies, i.e., VHF and L-band, and in tropical regions of the earth. Satellite circularly polarized antenna feed technology commonly employs bulkyand lossy 90-degree hybrid combiners to convert linear polarization to circular
polarization, which results in a higher noise figure for receive applications and a less
repeatable and more difficult design to tune and manufacture. This thesis aims at designing, modeling and simulating a prototype S/X dual bandCP feed/polarizer utilizing a technique known as the “Spread-Squeeze” polarizer, which
offers the advantages of compact size, ease of manufacture, and lower loss and noise
figure, relative to the current technology that often employs an external 3-dB hybrid
combiner. Ansys High Frequency Structure Simulator (HFSS), a commercial
electromagnetic modeling and simulation tool, is used for the simulations. Further, this thesis aims to characterize the performance of the dual feed hornwith respect to aperture efficiency, that is, the degree to which the feed horn illuminates
the parabolic reflector.
ContributorsCowan, Brad (Author) / Aberle, James (Thesis advisor) / Pan, George (Committee member) / Trichopoulos, Georgios (Committee member) / Arizona State University (Publisher)
Created2021
Description
Data transmission and reception has become an important aspect in day-to-day communication. With advancement in technology, it dictates the need for accurate data transmission and reception. For this very reason, wireless transceivers are employed in almost every industrial domain for numerous applications. A special concept of distributed transceivers is proven to be extremely useful in the latest technologies like Internet of Things. As the name suggests, this is a collaborative communication technique where multiple transceivers are synchronized for faster and much more reliable communication. This imposes a major challenge while designing this kind of a transceiver, as all the transceivers should be operating with carrier synchronization to maintain the proper collaboration. While there are several ways to establish this sync, this thesis emphasizes one of those techniques and tries to resolve the issue in design. The carrier synchronization is achieved using time division synchronization technique. Several challenges in implementing this technique were addressed using various models simulated in MATLAB Simulink and Keysight ADS. An in detail analysis has been performed for all the techniques used for this implementation to provide a diverse perspective.
ContributorsBoorela, Venkata Srilekhya (Author) / Zeinolabedinzadeh, Saeed (Thesis advisor) / Trichopoulos, Georgios C. (Committee member) / Aberle, James (Committee member) / Arizona State University (Publisher)
Created2021
Description
This dissertation consists of four parts: design of antenna in lossy media, analysisof wire antennas using electric field integral equation (EFIE) and wavelets, modeling and measurement of grounded waveguide coplanar waveguide (GCPW) for automotive radar, and E-Band 3-D printed antenna and measurement using VNA. In the first part, the antenna is modeled and simulated in lossy media. First, the vector wave functions is solved in the fundamental mode. Next the energy flow velocity is plotted to show near-field energy distribution for both TM and TE in air and seawater environment. Finally the power relation in seawater is derived to calculate the source dipole moment and required power.
In the second part, the current distribution on the antenna is derived by solving EFIE with moment of methods (MoM). Both triangle and Coifman wavelet (Coiflet) are used as basis and weight functions. Then Input impedance of the antenna is computed and results are compared with traditional sinusoid current distribution assumption. Finally the input impedance of designed antenna is computed and matching network is designed and show resonant at designed frequency.
In the third part, GCPW is modeled and measured in E-band. Laboratory measurements are conducted in 75 to 84 GHz. The original system is embedded with error boxes due to misalignment and needed to be de-embedded. Then the measurement data is processed and the results is compared with raw data.
In the fourth part, the horn antennas and slotted waveguide array antenna (SWA) are designed for automotive radar in 75GHz to 78GHz. The horn antennas are fabricated using 3D printing of ABS material, and electro-plating with copper. The analytic solution and HFSS simulation show good agreement with measurement.
ContributorsZhou, Sai (Author) / Pan, George (Thesis advisor) / Aberle, James (Committee member) / Palais, Joseph (Committee member) / Allee, David (Committee member) / Arizona State University (Publisher)
Created2021
Description
I present a trade-study of methods for a 1-port vacuum cryogenic in-situ calibration of a vector network analyzer. The three main methods I investigated in this work were: calibration using a commercial off the shelf latching electro-mechanical six way switch, a custom switch board, and a flexible multi channel stripline based printed circuit board. The test procedure was developed for use in a ground based closed-cycle cryogenic test bench to measure the reflection coefficient of a single port connectorized device under test. The device was installed in the cryogenic system alongside calibration standards. The goal of the trade study was to find which method could be used to accomplish calibration and device measurement in a single thermal cycle. Four cycles were required for industry standard open-short-load device calibration. Room temperature measurements were done with all three calibration schemes but ultimately only the single pole six throw switch proved effective enough for further testing. The cryogenic testing was carried out on an arbitrary device at ∼ 3K temperature, over a 6 GHz bandwidth. The final objective was to develop a setup and procedure for measuring the frequency and temperature dependent complex impedance of superconducting devices such as hot electron bolometer mixers, which are used for down converting the signal in the IF chain of astronomy instruments. Characterization of superconducting devices while they are at their operating temperature is challenging using traditional calibration methods. This commercial alternative is less expensive and more efficient in terms of thermal cycles and set up because it can be installed in a wide variety of cyrogenic systems.
ContributorsNeric, Marko (Author) / Trichopoulos, Georgios (Thesis advisor) / Groppi, Chris (Committee member) / Aberle, James (Committee member) / Arizona State University (Publisher)
Created2023
Description
Antenna arrays are widely used in wireless communication, radar, remote sensing, and other fields. Compared to traditional linear antenna arrays, novel nonlinear antenna arrays have fascinating advantages in terms of structural simplicity, lower cost, wider bandwidth, faster scanning speed, and lower side-lobe levels. This dissertation explores a novel design of a phased array antenna with an augmented scanning range, aiming to establish a clear connection between mathematical principles and practical circuitry. To achieve this goal, the Van der Pol (VDP) model is applied to a single-transistor oscillator to obtain the isolated limit cycle. The coupled oscillators are then integrated into a 1 times 7 coupled phased array, using the Keysight PathWave Advanced Design System (ADS) for tuning and optimization. The VDP model is used for analytic study of bifurcation, quasi-sinusoidal oscillation, quasi-periodic chaos, and oscillator death, while ADS schematics guide engineering implementation and physical fabrication. The coupled oscillators drive cavity-backed antennas, forming a one-dimensional scanning antenna array of 1 times 7. The approaches for increasing the scanning range performance are discussed.
ContributorsZhang, Kaiyue (Author) / Pan, George (Thesis advisor) / Yu, Hongbin (Committee member) / Aberle, James (Committee member) / Palais, Joseph (Committee member) / Arizona State University (Publisher)
Created2023
Description
Terahertz (THz) waves (300 GHz to 10 THz) constitute the least studied part of the electromagnetic (EM) spectrum with unique propagation properties that make them attractive to emerging sensing and imaging application. As opposed to optical signals, THz waves can penetrate several non-metallic materials (e.g., plastic, wood, and thin tissues), thus enabling several applications in security monitoring, non-destructive evaluation, and biometrics. Additionally, THz waves scatter on most surfaces distinctively compared with lower/higher frequencies (e.g., microwave/optical bands). Therefore, based on these two interesting THz wave propagation properties, namely penetration and scattering, I worked on THz imaging methods that explore non-line-of-sight (NLoS) information. First, I use a THz microscopy method to probe the fingertips as a new technique for fingerprint scanning. Due to the wave penetration in the THz range, I can exploit sub-skin traits not visible with current approaches to obtain a more robust and secure fingerprint scanning method. I also fabricated fingerprint spoofs using latex to compare the imaging results between real and fake fingers. Next, I focus on THz imaging hardware topologies and algorithms for longer-distance imaging applications. As such, I compare the imaging performance of dense and sparse antenna arrays through simulations and measurements. I show that sparse arrays with nonuniform amplitudes can provide lower side lobes in the images. Besides, although sparse arrays feature a much smaller total number of elements, dense arrays have advantages when imaging scenarios with multiple objects. Afterward, I propose a THz imaging method to see around obstacles/corners. THz waves’ unique scattering properties are helpful to implement around-the-corner imaging. I carried out both simulations and measurements in various scenarios to validate the proposed method. The results indicate that THz waves can reveal the hidden scene with centimeter-scale resolution using proper rough surfaces and moderately sized apertures. Moreover, I demonstrate that this imaging technique can benefit simultaneous localization and mapping (SLAM) in future communication systems. NLoS images enable accurate localization of blocked users, hence increasing the link robustness. I present both simulation and measurement results to validate this SLAM method. I also show that better localization accuracy is achieved when the user's antenna is omnidirectional rather than directional.
ContributorsCui, Yiran (Author) / Trichopoulos, Georgios (Thesis advisor) / Balanis, Constantine (Committee member) / Aberle, James (Committee member) / Alkhateeb, Ahmed (Committee member) / Arizona State University (Publisher)
Created2022