Microwave program - senior projects

ABSTRACT
This senior capstone project involves the design, fabrication, testing, and measurements of an integrated receiver front-end for the SDARS (Satellite Digital Audio Radio Service. The signal originates at the radio studios from where it is transmitted to the three Sirius satellites that will then broadcast to earth. Ground repeaters are also implemented to transmit the signal and make possible a clear sound even through tunnels and potential attenuating factors such as buildings.
A receiver picks up the best input of the broadcasted signals and reproduces the high quality audio contained in the signal from the satellites. The front-end receiver consists of a circularly polarized antenna, a low-noise amplifier and a bandpass filter. This project involves the design, test, fabrication and measurements of these components individually as well as the integrated module consisting of these components

ABSTRACT
Driver errors cause a majority of all car accidents. Forward collision avoidance systems aim at avoiding, or at least mitigating, host vehicle frontal collisions, of which rear-end colissions are one of the most common. Either warning the driver does this or braking or steering away, respectivelly, where each action requires its own considerations and design. This senior capstone project involves the design, fabrication, test, and measurements of antenna array for automotive collision avoidance system.

ABSTRACT
Voltage controlled oscillators (VCOs) are an essential to the world of communications. They work to provide flexibility and stability for public, military, and space communications such as cellular phones, radar, and satellite communications. As the bandwidth of frequencies that the VCO can tune to increases, its usefulness increases. Therefore it is imperative to achieve a high tuning standard. Distributed amplifiers are known quite well for their ability to create a high, steady gain over a large operating frequency range. The main objective of the capstone project titled “Distributed Amplifier Based Voltage Controlled Oscillator” is to study the feasibility of using a distributed amplifier to increase the bandwidth at which the overall system can operate.

SDARS Front-End Receiver
by :   Greg Zomchek &
         Erik Zeliasz
Advisor :   Dr. Prasad Shastry
May 2001

ABSTRACT
This senior capstone project involves the design, fabrication, test, and measurements of a front-end receiver for SDARS (Satellite Digital Audio Radio Service). The goal was to receive the SDARS signal utilizing multiple components to convert it to an intermediate frequency of 70 MHz.

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Active Duplexer for PCS Transceivers
by :   Wesley J. Bond
Advisor :   Dr. Prasad Shastry
May 2000
ABSTRACT
   In this project, the design and performance of an active duplexer for a personal communication system (CDMA) operating at 1.9GHz is presented.
   The objective of this project is to design an active duplexer for a wireless CDMA communication system that operates at 1.9GHz. A PCS system already exists and is incorporating an active duplexer, but this project is to improve the response of the current design. At the present time the system is using two separate DC voltages to bias the amplifiers. The goals is to use a unipolar power supply, or in other words just one DC voltage to bias the amplifiers. Another goals is to incorporate the existing bias-T's onto the circuit board.
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ABSTRACT
   From the Global Positioning System, cellular telephones, direct satellite television, and now to wireless internet access, digital wireless communication is completely changing the world we live in! In this project, the design and performance of a Personal Communication System (PCS) Code Division Multiple Access (CDMA) Receiver to IS-95 standards...more simply, a digital cellular telephone receiver!
   CDMA communication systems are based on spread spectrum (SS) techniques that allow many users to communicate to each other over the same frequency band at the same time because of a unique code assigned to each user's phone. This spectral efficiency allows for increased user capacity and lower transmission power than other multiple access technologies such as Frequency Division Multiple Access (FDMA), which assigns a unique frequency bandwidth for each user, and Time Division Multiple Access (TDMA) that assigns different time slots over the same frequency bandwidth for all users.
   CDMA technology is very complex, and a solid understanding of it's basic principles must be grasped before one can expect to successfully design and build a CDMA system. This project have covered the main principles involved for the design of a CDMA PCS cell phone receiver.
   This project covered signal spreading using a PN code. This code distinguishes cell sites from each other. Walsh codes are used to distinguish users from each other. They are important in keeping interference down to a minimum because of their orthogonal nature.

ABSTRACT
Wireless systems are expanding throughout the world at an extraordinary pace. They have applications in many electronic areas including the Internet, personal communications, and audio equipment. The goal of our senior project is to design and build a wireless audio link that will transmit a stereosignal from an audio source to a stereo system so that it can be played on a set of speakers. The system will work in a transmission range that is in an unlicensed band as defined by the Federal Communications Commission. The unlicensed ISM band ranges from 902MHz-928MHz.

ABSTRACT
The project that is described in this report is the design, fabrication, and testing of an active microstrip antenna. In an active antenna, an active device such as an amplifier or an oscillator is integrated with the passive antenna. This particular active antenna has been designed for use with GPS devices. The two-stage amplifier approach will be used, since it can provide low noise (<2dB) and high gain (>25dB). Two GaAs MESFETs are used as the active devices to provide signal gain. Simulation results from Hewlett Packard's linear simulator EEsof and data from the tested circuit are presented and discussed.

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Active Mixer
by :   Shawn Parker
Advisor :   Dr. Prasad Shastry
May 1998
ABSTRACT
   Active mixers have applications in a wide range of communication systems. In this project, a GaAs MESFET is used as the active device. Active mixers have a conversion gain. This is an important advantage over passive diode mixers, which have a conversion loss. This report will cover the design and testing of an active mixer. The design issues, specifications, and measured results are presented.
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ABSTRACT
The intent of this project is to design and create a user-friendly system that transmits the audio signal of a musical instrument or a microphone to the instrument's amplifier via an analog, wireless communication link, which thereby replaces the use of cumbersome cords. The transmitter needs to be portable, and have a broadcast range suitable for its application, while complying to FCC standards specified by Part 15. Techniques for noise and distortion reduction, and link budgeting are included in the design.

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24 GHz Proximity Sensor
by : Bruce E. Unger & Chad Campen
Advisor : Dr. Prasad Shastry
May 1997

ABSTRACT
In today's society, the need for new products to increase the safety of the individuals is apparent. Several products are now being developed in the wireless communications industry for this purpose. The 24GHz Proximity Sensor utilizes radar technology to determine and display the range of a stationary object with respect to the radar. This project can affect the world directly, especially in the automotive industry. As a result of mounting the system on the rear bumper of an automobile, the range of stationary objects behind the vehicle will be provided to the driver of the car.
This project is designed around the Northrop Grumman TR1G946 Monolithic Microwave Integrated Circuit (MMIC) transceiver chip. Objectives include background research of the radar technology, characterization of the transceiver chip, and the system design principle to extract the range information. Utilizing multiple frequency continuous wave radar, the intermediate frequency output of the transceiver chip is a square wave if the transmitter signal is switched between two frequencies. The peak to peak amplitude of the square wave is proportional to the desired range, which can then be displayed to the driver of the automobile.

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A Compact 2.4 GHz Voltage Control RF Coupler
by : Aaron Dietrich
Advisors : Dr.Santiago Navarro & Dr. Prasad Shastry
May 1997

ABSTRACT
The recent trend in wireless communications product design has been to make the end product smaller. In order to reduce it's size, the individual component's sizes need to be decreased. One component used in RF transceivers that needs to be made small is a matched variable attenuator. The report introduces the attenuator by discussing a standard attenuator. A detailed description of the design improvement and testing procedure using the network analyzer is then discussed in the report. Finally, the test results of the improved attenuator are compared and contrasted with the attenuator that was designed and tested last year.

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A 2.4 GHz Matched Variable Attenuator
by : Melissa Anderson & Dana Gardner
Advisors : Dr. Prasad Shastry & Dr.Santiago Navarro
May 1996

ABSTRACT
A 2.4 GHz Matched Variable Attenuator is a part of a Transceiver Chip used in Personnel Communication Systems. The following report describes the research and design accomplished in the 2.4 GHz Matched variable Attenuator project. The report introduces the attenuator by explaining its functions and applications. A detailed description of the attenuator's internal Microwave components and the design procedure using HP-EEsof simulation software is included. Next, the fabrication technique and an explanation of testing procedures using a network analyzer is discussed. Finally, the test results of the simulated and fabricated attenuator are compared and contrasted.

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Linearizing Microwave Amplifier
by : Sean Middleton & Babar Baig
Advisors : Dr. Prasad Shastry & Dr.G.L.Dempsey
May 1996

ABSTRACT
In many RF applications, such as satellite and personnel communications, there is a need for high power with less distortion. This project analyzed the problems associated with using high power RF amplifiers at 4.0 GHz. In order achieve extended input-output power characteristics of an amplifier, an active feedback methodology was proposed. Design of the system consisted of a main amplifier, an auxiliary amplifier in the feedback loop, input and output couplers, and biasing networks. By utilizing active feedback, non-linearities of the amplifier were reduced and useful linear range of the amplifier was extended. This project was designed using the EEsof libra tools and fabricated at the microwave fabrication facility at Bradley University. Furthermore, final testing proved that active feedback extends the useful range of the amplifier by approximately 3dB.

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A 2.4 GHz Transmit/Receive module for Wireless Communications
by : Jalmi Shafary Abdul-Jalil & Tuan Tu
Advisor : Dr. Prasad Shastry
May 1995

ABSTRACT
In this senior project report, the design and performance of a 2.4 GHz Transmit/Receive Module for Wireless Communications are presented. The results of the simulations as well as experiments as discussed. The Bi-Directional Amplifier was realized in the hybrid Microwave Integrated Circuit (MIC) form. EEsof Libra and Academy CAD packages as well as CAMAD, MSTRIP software were used in the design process.

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The Wireless Group
by : David Baietto, Todd Ciccone, Keith George, Timothy Hahn, & James Menne
Advisors : Dr.I.W.Sennot, Dr.B.D.Huggins, & Dr. Prasad Shastry
May 1995

ABSTRACT
The field of wireless communication is rapidly expanding with the emergence of personal pagers, cellular mobile radio systems, vehicle tracking, and commercial use of GPS. Multipath and interference from other users are the two basic problems the designer must face. Spread Spectrum, Code Division Multiple Access (CDMA), is proving to be available technique for modern wireless communications due to its ability to efficiently incorporate many users within a relatively wide bandwidth. It was the Wireless Group's intention to design, construct, and test a network for wireless communication using spread spectrum. The goal was to make a network capable of transmitting information from a portable user unit to a receiving base station. Possible continuations of this project could involve the addition of a number of users in a two-way communication link.

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A 2.4 GHz Transceiver For Wireless Communications
by : Eric Haakenson
Advisors : Dr. Prasad Shastry
May 1994

ABSTRACT
Wireless communication refers to the new technology of replacing phone lines by transmitting voice and data through the air at lower microwave frequencies (2.0 - 4.0 GHz). This frequency band has been allocated by the FCC for Personal Communication Systems (PCS), Wireless Local Area Networks (LAN) and wireless television. This Project entails testing and running Northrop's 2.4 GHz MMIC Transceiver for Wireless Communications. One aspect of the project entails design and fabrication of a microwave circuit board to test the Transceiver chip. It also entails design, fabrication and testing of passive components such as microstrip bandpass filters, power dividers, and lumped element impedance matching networks. The designs of the circuits as well as results of test and measurement will be presented.

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A 2.4 GHz Electronic Tether: Digital Subsystem
by : Jeff DeMott & Luke Moranda
Advisors : Dr.I.W.Sennot & Dr.B.D.Huggins
May 1994

ABSTRACT
Monitoring a young child in a crowded public area can be a difficult job. The electronic tether addresses this problem. The electronic tether is a child monitoring device which measures the distance between the child and parent, setting off an alarm to alert the parent when the child has wondered too far away. Existing systems that attempt this distance measurement are based on estimating propagation loss. This has proven to be inaccurate due to interference, multipath, and varying component attenuations. Using more sophisticated correlation techniques, the dependency of the measurements upon signal strength has been eliminated. Measuring the correlation between two reference signals and the received signal delayed by the round-trip path delay, yields an accurate distance measurement.

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A 2.4 GHz Electronic Tether: RF Subsystem
by : Len Bergman & Sterling Toedtemeier
Advisors : Dr.I.W.Sennot & Dr.B.D.Huggins
May 1994

ABSTRACT
As society grows, parents become more concerned for the security of their children. The "Electronic Tether" assists parents in keeping track of where their children are located. This is a joint project broken into three subsystems: RF (radio frequency), Digital Systems, and Power. Communication was accomplished between the child's unit and the parent's unit by an RF link at 2.4 GHz. Through the use of microstrip and microstrip surface mount components a PRN code was modulated onto a 2.4 GHz signal and transmitted. At the receiver correlation data and distance information was determined by the use of a system constructed from surface mount mixers, SAW filters, and VCO's.

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A 2.4 GHz Electronic Tether: Power Subsystem
by : Dave McDermott
Advisors : Dr.I.W.Sennot & Dr.B.D.Huggins
May 1994

ABSTRACT
The electronic tether project consists of an interrogator and transponder unit which are both portable. The interrogator is powered by two AA batteries and the transponder by two button cell batteries. The interrogator unit consists of digital components including a microprocessor, two VCOs, and RF equipment. These VC0s have an equivalent load of 167 ohms while operating at 3 V and the microprocessor is 333 ohms at 5V. For this reason, there are two DC to DC up converters on the interrogator which maintain constant output until the input level drops beneath 1.6V. The transponder consists of digital components and one VCO. One DC to DC converter is required for the 3 V required by the VCO. The converters have low power indicators which trigger an alarm when the input voltage falls beneath 2V.

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A 4 GHz FET Power Amplifier
by :   Ismail Mazlan
Advisor :   Dr. Prasad Shastry
May 1993
ABSTRACT
    In this report the design and performance of a GaAs FET Power Amplifier in the range 3.7 to 4.2 GHz are presented. The results of simulations and experiments are discussed. The amplifier was realized in the hybrid MIC form. EEsof Touchstone, Libra and Academy CAD packages as well as MATCHNET software were used in the design process.
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4 GHz GaAs FET Low-Noise Amplifier
by :   Abdul Hisham Mohd Arif & Nor Azman Azit
Advisor :   Dr. Prasad Shastry
May 1993
ABSTRACT
   In this report the design and performance of a GaAs FET Low-Noise Amplifier in the range from 3.7 to 4.2 GHz are presented. The results of simulation as well as experiment are discussed. The amplifier was realized in the hybrid MIC form. EEsof Touchstone and Academy CAD packages were used in this design process.
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A Push-Pull Distributed Microwave Amplifier
by : G.Brubaker
Advisor : Dr. Prasad Shastry
May 1992

ABSTRACT
The Push-Pull Distributed Microwave Amplifier is composed of several amplifier stages. First, a description of the fundamental concepts of the amplifier will be presented in order to clarify its operation and design considerations. Second, the amplifier will be subdivided into 'cells' which will facilitate design and analysis considerations. Finally, with the amplifier cell sections connected together, the operation of the complete amplifier will be discussed and the results of the computer-aided simulations of the 2-6 GHz amplifier will be presented.

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