Historical+Information

Tags: [|Absorbing panels], [|Agilent 8648B signal generator], [|Agilent E4402B spectrum analyzer], [|Agilent U2001A power sensor], [|Antenna characteristics test], [|Antenna Controller], [|Antenna under test (AUT)], [|Frequency doubler circuit], [|LabVIEW VI], [|L-Com HG2415EG], [|Mini-Circuits SSG-4000HP signal generator], [|Stepper motor], [|Turntable]

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=HISTORICAL INFORMATION=

This page contains all of the old equipment and test procedures used in the antenna range that have since been replaced or improved upon. This information is posted here for reference and for those interested in learning more about the evolution of the Marquette University Antenna Range. After viewing this page, you will know about all of the equipment once used in the antenna range along with the history of changes made. For a more graphical representation of the evolution of the antenna range, see the Timeline page.

= = =Justification=
 * ==== Contents ====
 * Justification
 * Design
 * Equipment (Outdated)
 * Agilent 8648B Signal Generator
 * Frequency Doubler Circuit
 * Pedestal with Pole Configuration
 * Software (Outdated)
 * LabVIEW VI
 * Tests (Outdated)
 * "Interference In" Test
 * "Interference Out" Test ||
 * For the past two decades, the College of Engineering at Marquette University has provided classes dedicated towards antenna theory and design. While design is a major class element, the tools available to students prior to the antenna range for proper design and analysis were limited. At the time, the main instrument available to students was the spectrum analyzer. While a spectrum analyzer is crucial in antenna design because it allows for the ability to make characteristic measurements such as impedance, phase, and return loss, it alone cannot offer students the ability to measure and analyze one of the most important antenna characteristics, namely, the radiation pattern of an antenna. By having developed a system that allows for such measurements was the basis for the project. With the collaboration of Dr. James Richie at Marquette University, this project was developed in order to create a unique and dedicated facility within the College of Engineering that will grant both students and faculty the ability to bridge theory with a practical and functional method of design analysis.
 * The initial construction of the antenna range was coordinated by the 2012-2013 E55 senior design team and was inspired by the 2011 IEEE Antenna and Propagation Society Student Design Challenge, "Radiation Patterns on a Budget" 10]. The primary goal of the challenge was to develop a facility capable of measuring relative antenna radiation patterns within a budget of $1500.

Design

 * **Note:** The design concepts outlined below are no longer representative of the current design. Details on the most current iteration of the design of the Marquette University Antenna Range can be found on the Overview page.


 * The preliminary design of the antenna range is shown below. This block diagram was produced by the 2012-2013 E55 senior design team. The overall system process is very similar to how the antenna characteristics tests are performed today in the antenna range.
 * It is important to note that this initial design was not 100% met, but it did lay the groundwork for the next two senior design teams to follow in terms of improving the antenna range.




 * Below is the updated block diagram created by the 2013-2014 E55 senior design team. When comparing the two designs, again the overall process is the same but with a few key differences. This new design highlights the improvements made by this team, most notably the implementation of the CPU Automated Program, otherwise known as the Antenna Controller program, and the power sensor. This block diagram is an accurate representation of the antenna characteristics test process used in the antenna range today.




 * Below is a video of an example antenna characteristics test performed by the 2013-2014 E55 senior design team, before the wooden pole was replaced with the turntable. It is still a relevant example for how the test is performed today.

media type="youtube" key="Z6jkb8zy2C8" height="480" width="854"

Equipment (Outdated)

 * **Note:** The equipment listed here is no longer in use. A detailed list of equipment currently in use by the Marquette University Antenna Range can be found on the Equipment page.


 * ** Agilent 8648B Signal Generator **
 * [[image:Agilent 8648B Signal Generator.png width="137" height="98" align="right" caption="Agilent model 8648B signal generator."]]This signal generator pictured right was primarily used by the 2012-2013 and 2013-2014 E55 senior design teams to perform antenna characteristics tests at the antenna range. It was replaced in January, 2016 by the 2015-2016 E55 senior design team with the Mini-Circuits SSG-4000HP signal generator.


 * ** Frequency Doubler Circuit **
 * [[image:Frequency doubler circuit.PNG width="194" height="94" align="right" caption="Frequency doubler circuit."]] A signal manipulation circuit dubbed the "frequency doubler circuit" designed and implemented by the 2012-2013 E55 senior design team was used with the Agilent 8648B signal generator before it was replaced with the Mini-Circuits SSG-4000HP signal generator. The output frequency range of the Agilent 8648B was limited to a range of 9 kHz to 2 GHz. This range did not offer the desired output frequency of 2.4 GHz so the frequency doubler circuit was constructed to achieve that frequency for the transmitted signal.
 * The system was designed in an enclosure that could be easily connected to the test instrumentation via standard connections in order to minimize the handling of its sensitive components. Below is a graphic depicting the cascaded system of the amplifier, multiplier, another amplifier, and a filter, along with the fully constructed system.




 * The 2012-2013 E55 senior design team conducted a performance benchmarking test of the frequency doubler circuit, and confirmed that it worked as planned, converting a 1.2 GHz signal from the signal generator to a 2.4 GHz signal at 13.8 dBm with little noise. The image of the output of the spectrum analyzer from the test is shown below.




 * ** Pedestal with Pole Configuration **[[image:Pole configuration.png width="187" height="252" align="right" caption="Wooden pole configuration."]]
 * The wooden pole was set up by the 2012-2013 E55 senior design team to automate the antenna characteristics testing process. It was connected directly to the stepper motor which was controlled by the LabVIEW VI, and later with the Antenna Controller program, when it was set up by the 2013-2014 E55 senior design team.
 * While automating the testing process was an essential step, the wooden pole posed a few issues.
 * Rotating the antenna around the pole displaced it by a number of inches, generating inaccurate gnuplots of the radiation pattern of the antenna under test (AUT).
 * The wooden pole wobbled, making sharp, unwanted lobes on the radiation pattern plots.
 * Only small antennas could be mounted, restricting the potential flexibility of the antenna characteristics test to only a few types of antennas.
 * The wooden pole was replaced with the turntable by the 2015-2016 E55 senior design team in order to make the setup more stable, flexible, and accurate.

**Software (Outdated)**
 * **Note:** The software listed here is no longer in use. A detailed list of software currently in use by the Marquette University Antenna Range can be found on the Software page.


 * ** LabVIEW VI **
 * While not thoroughly documented, prior to the implementation of the Antenna Controller program by the 2013-2014 E55 senior design team, the 2012-2013 E55 senior design team programmed a LabVIEW VI to obtain the initial antenna characteristics test results.
 * The function of the program was to communicate with the stepper motor so the user could manually rotate the antenna under test (AUT) while another user could record power received values using the spectrum analyzer.
 * While the Antenna Controller program was a massive improvement to the automation of the testing process, it is speculated that the process can be further automated by returning to LabVIEW to program a more complex VI to control all testing processes.

Tests (Outdated)

 * **Note:** The two tests below refer to a time before the anechoic chamber was completely built. Since the anechoic chamber is complete and fully enclosed by absorbing panels, the results of these tests no longer have significant impact on antenna characteristics test results. A list of available tests and testing procedures can be found on the Tests page.


 * ** "Interference In" Test **
 * This test was performed by the 2012-2013 E55 senior design team to measure incoming interference from different electronic sources.
 * Information gathered from this test provides insight on why it is important to use signal absorbing material to prevent this interference.
 * Without any absorbing panels set up, the first model of receive antenna was used, and was rotated continuously without a test signal running. The spectrum analyzer was used to detect any peak power readings.
 * No noticeable noise was found in the band of interest, so deliberately created sources of interference were set up and tested, as can be seen below.




 * ** "Interference Out" Test **
 * The 2012-2013 E55 senior design team monitored internet speed changes when transmitting a signal compared to not transmitting. The result of the test is shown below.