Collected+Data

Tags: [|Absorbing panels], [|Agilent E4402B spectrum analyzer], [|Agilent U2001A power sensor], [|Antenna characteristics test], [|Antenna Controller], [|Antenna under test (AUT)], [|Arduino Uno R3 microcontroller], [|Corner Reflector], [|Far-field], [|Free-space VSWR test], [|Frequency doubler circuit], [|LabVIEW VI], [|L-Com HG2415EG], [|Mini-Circuits SSG-4000HP signal generator], [|Monopole antenna] , [|Pedestal], [|Quiet zone], [|Roomba robot], [|Stepper motor], [|Transmit antenna], [|Turntable], [|Yagi-Uda array]

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=COLLECTED DATA=

A collection of data obtained using the Marquette University Antenna Range is displayed here. The tests were performed by the three different senior design teams that worked on the antenna range. After viewing this page, you will know about the results of various antenna characteristics tests, the free-space VSWR test, equipment benchmarking tests, and other preliminary tests performed at the antenna range. To view tests related to outdated equipment or procedures, see the Historical Information page.

= = = Antenna Characteristics Test Results =
 * ==== Contents ====
 * Antenna Characteristics
 * Free-Space VSWR Test Results
 * Range
 * Azimuth
 * Equipment Benchmarking
 * Power sensor
 * Signal generator
 * Pedestal
 * Absorbing Panels ||
 * ** L-Com HG2415EG **
 * The first documented antenna characteristics test was performed by the 2012-2013 E55 senior design team on the L-Com HG2415EG antenna. This antenna under test (AUT) was rotated manually 1.8 degrees per step for 200 steps. The power received was measured using the spectrum analyzer.
 * The results of this test are shown below on the left. This result is compared to the result taken from the specification sheet of the antenna that is shown below on the right.
 * In this comparison, it is important to note that the graph below on the left is on a linear scale while the graph below on the right from the specification sheet is on a logarithmic scale. This discrepancy explains the difference in amplitudes. The main and side lobes are present, which indicates that the test is relatively accurate for the equipment utilized. The most significant difference is the back lobe, which could be explained by the counterbalance of the antenna deflecting radiation around the corner reflector.




 * After the 2013-2014 E55 senior design team designed the automated Antenna Controller program, the following gnuplots were created of the L-Com HG2415EG antenna radiation patterns obtained at various step sizes. The results are shown below. It is clear from these results that using the smallest step size of 1.8 degrees with the Antenna Controller program provides the most precise radiation patterns. It was not indicated whether these tests were performed with the blue absorbing panels set up or not.




 * Additional tests were performed by the 2013-2014 E55 senior design team to determine the effectiveness of the newly installed blue absorbing panels. Below is the result of the antenna characteristics test performed on the L-Com HG2415EG antenna with and without the blue absorbing panels set up.
 * ** Corner Reflector **
 * The corner reflector was used in an antenna characteristics test to assess the effectiveness of the newly installed turntable and the new "quiet zone" located by the 2015-2016 E55 senior design team. Below are the gnuplots obtained using the turntable, both when the corner reflector was placed in the far-field and when it was placed in the quiet zone.




 * Based on visual inspection, it is clear that the turntable installation vastly improved the smoothness of the corner reflector antenna radiation pattern. In addition, placing the corner reflector in the quiet zone revealed more defined nulls and lobes than in the far-field, indicating that there are less unwanted reflections of transmitted electromagnetic waves. As was discussed in the Receiver section of the Overview page, the issue that arose from determining the location of the quiet zone is contradictory to the purpose of the antenna range being designed as a far-field range. This issue is further discussed on the Future Work page.


 * ** Yagi-Uda Array **
 * A Yagi-Uda array was brought in by Dr. Henry Thompson for an antenna characteristics test, which was performed by the 2015-2016 E55 senior design team. The most up-to-date antenna characteristics test procedure was used, along with the most current equipment. Below are the results of the test.



**Free-Space VSWR Test Results**
 * The free-space VSWR test was performed by the 2015-2016 E55 senior design team to measure the quality of the anechoic chamber. To assess the quality, the objective was to locate the "quiet zone" of the anechoic chamber, otherwise known as the area where the reflections of electromagnetic waves being transmitted coming from anywhere but the transmit antenna are at a minimum.
 * The Roomba robot was connected to an Arudino Uno R3 microcontroller to move the monopole antenna across the inside of the anechoic chamber in both the transversal and longitudinal directions. For the purposes of the specific tests performed by that team, the longitudinal test was referred to as the "range test" and the transversal test was referred to as the "azimuth test".
 * A graphic was created to display an overhead view of the patterns made by the Roomba with the antenna under test (AUT), which is shown below.




 * To evaluate the quiet zone of the anechoic chamber, the International Standard 2.1 edition published by CISPR was the main document referenced by the 2015-2016 E55 senior design team. Since the typical frequency used in operation of the antenna range is 2.4 GHz, the VSWR specification for the 1 GHz to 18 GHz range according to the International Standard is “SVSWR ≤ 2:1, or SVSWR,dB ≤ 6,0 dB” 8]. This standard assisted in analyzing the data acquired from the free-space VSWR test using the Roomba, by specifying the appropriate range in dB to determine the quiet zone.


 * ** Range Test (x-axis) **


 * The 3 dB range as indicated above is the determined quiet zone for the anechoic chamber. This area was measured to be between 2.17 meters and 2.30 meters from the transmit antenna.


 * ** Azimuth (y-axis) **


 * From visual inspection, it was concluded that the quietest part of the anechoic chamber with regards to the result of the azimuth test was directly in front of the transmit antenna.

Equipment Benchmarking Test Results

 * ** Agilent U2001A Power Sensor **
 * To verify the accuracy of the power sensor installed by the 2013-2014 E55 senior design team, a series of power measurements were taken by both the new power sensor and the spectrum analyzer. The detailed test plan and qualitative results are shown below.
 * Regarding these qualitative results, it is important to note that the power sensor benchmarking test was performed with the frequency doubler circuit connected. This circuit, when powered, increased the power of the signal by 13 dBm. When the signal generator transmitted a signal at less than 0 dBm, the circuit did not perform correctly. For that, it was important to compare only the values of the power received by the spectrum analyzer and the power sensor, while using the power setting of the signal generator as a reference.




 * The quantitative results of the test are shown below.
 * Regarding these quantitative results, the reading at -7.0 dBm for the signal generator there appeared to be a discrepancy in the readings when comparing the spectrum analyzer and the power sensor. It was determined that the probable cause was due to loose ports that could have been more tightly fastened.




 * The power values recorded from the spectrum analyzer and the power sensor in the 0.0 to -10.0 dBm range were very similar, only having a difference greater than 3% in one data point.
 * The data recorded from the spectrum analyzer and the power sensor in the -10.0 to -25.0 dBm was once again similar. From the -25.0 dBm to -50 dBm range, however, the measurements jumped around a lot, indicating a need to make a rough estimate on an average power. This is somewhat due to the fact that the Agilent U2001A power sensor records 110 readings per second. Overall, the power sensor benchmarking test was a success, as the values recorded from the spectrum analyzer and the power sensor compared very well.


 * ====== **Mini-Circuits SSG-4000HP Signal Generator** ======
 * The signal generator was tested using the spectrum analyzer in February, 2016, by the 2015-2016 E55 senior design team. The results shown below verify that when attenuated with 13 dB, the signal is accurate in terms of operating frequency and power.
 * With a set output power of 13 dBm and output frequency of 2.4 GHz on the signal generator control, the spectrum analyzer produced the trace shown below.




 * The measured output power was at -0.672 dBm with a frequency bandwidth of 2.39 to 2.41 GHz.
 * It was speculated that the extra 0.672 dB of attenuation is due to the small amount of loss from the short length of coaxial cable used to attach the spectrum analyzer to the signal generator.
 * The results recorded at this time considered the signal generator to be sufficiently accurate to conduct antenna characteristics tests.


 * ** Pedestal **
 * A spin calibration test was performed on the stepper motor by the 2012-2013 E55 senior design team to verify its accuracy.
 * It is important that the pedestal turns 360 degrees in a specified number of steps.
 * The initial position of the antenna was marked on the box.
 * The LabVIEW VI was set to rotate 1.8 degrees per step for 200 steps. After 200 steps, the final position of the antenna was marked. The final and initial marks were indistinguishable.

= Absorbing Panels Test =
 * To fully set up the anechoic chamber in the antenna range, the 2013-2014 E55 senior design team designed and constructed six additional blue absorbing panels. To verify the effectiveness of their design, they performed a test to determine changes to the noise level in the anechoic chamber with and without the six blue absorbing panels.
 * It is clear that the blue absorbing panels make a small improvement, averaging a lowering of the noise floor by about 6.33 dB. The results are shown below. The marginal difference was attributed to a non-ideal chamber geometry. This suspicion was confirmed after consulting members of the Microwave Seminar for feedback.