Tests

Tags: [|Absorbing panels], [|Agilent U2001A power sensor], [|Antenna characteristics test], [|Antenna Controller], [|Antenna range safety], [|Antenna under test (AUT)], [|Arduino Uno R3 microcontroller], [|Far-field], [|Free-space VSWR test], [|Lab computer], [|Mini-Circuits Generator], [|Mini-Circuits SSG-4000HP signal generator], [|Monopole antenna], [|Pedestal], [|Power Panel 3.7], [|Quiet zone], [|Radiation absorbent material], [|Roomba movement program], [|Roomba robot], [|Stepper motor], [|Transmit antenna], [|Turntable], [|Wooden track]

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=TESTS=

This page is the main hub for information regarding the kinds of tests available at the antenna range. Below you will find detailed procedures on how to perform each test and what equipment and software is required. It is recommended that before performing tests in the antenna range, the user should refer to the Safety and Legal page for information regarding proper procedures while testing. After viewing this page, you will be well-informed about proper test procedures for all of the tests available at the antenna range.

= = =Antenna Characteristics Test= ==== This is the primary test for analyzing antennas under test (AUTs) and their characteristics, providing the user with information about the quality of their antenna in the form of a radiation pattern. Since this test is designed to perform with a signal frequency of 2.4 GHz, signals from Wi-Fi, cell phones, and microwave ovens can potentially cause trace amounts of interference. Tests involving external signal sources causing interference were performed by the 2012-2013 E55 senior design team and can be found on the Collected Data page. Although the potential interference is very low, it is recommended that prior to performing a test, cell phones should not be held or placed within visual range of the receive antenna. In addition, it is advised to stand behind the transmit antenna while a test is taking place for safety concerns. ====
 * ==== Contents ====
 * Antenna Characteristics Test
 * Roomba Robot Free-Space VSWR Test
 * Range (x-axis) test
 * Azimuth (y-axis) test ||
 * ====** Equipment Required: **====
 * ==== Mini-Circuits Model SSG-4000HP signal generator ====
 * Transmit antenna
 * Antenna under test (AUT)
 * Agilent U2001A power sensor (**Note:** Unless conducting test at 2.4 GHz, remove the 2.4 GHz bandpass filter)
 * ==== Pedestal ====
 * ==== Green foam slabs as needed ====
 * Lab computer
 * ** Software Required: **
 * Antenna Controller
 * Power Panel 3.7
 * Mini-Circuits Generator
 * ====** Procedure: **====
 * If not done so already, place the pedestal in either the far-field, or the designated "quiet zone", which are marked in the anechoic chamber as shown below.




 * Center the receive antenna so that it is in a straight line horizontally from the transmit antenna.
 * The side of the wooden box not covered in absorbing material, i.e., the side with the cables coming out, should be facing away from the transmit antenna.
 * Adjust the height or setup as necessary with green foam slabs, as seen below. It is important to make sure the AUT is close to the same vertical height as the transmit antenna to increase accuracy. The measured height of the transmit antenna is 4 feet, 7 inches above the ground.




 * Mount the antenna. To do this, follow the steps outlined below:
 * Acquire an SMA male end (or adapter) and fix it to the antenna.
 * Connect the SMA connector from the antenna to the adapter located at the center of the turntable, pictured below.




 * A small length of coaxial cable should already be attached to the underside of the turntable.
 * There is no need to pre-coil any wires, since the attached coaxial cable should wrap around the white plastic mounting block inside the housing box as the turntable turns. However, look inside the housing box and ensure that the coaxial cable is not wrapped around the block. Refer to the graphics below.




 * There are three cables coming out of the back of the wooden housing box, as shown below.




 * ==== Connect all three of the cables pictured above in the manner shown below. ====
 * The "Power cable" connects to the cable labeled "Step motor power" below.
 * The "Motor control" connects to the cable labeled "Step motor control" below.
 * The "Coaxial cable" connects to the power sensor, which has a USB cable that connects to the cable labeled "Power sensor" below.




 * ==== At this point, everything inside the anechoic chamber is prepared, so the next step is to close the door to the range by stacking the four blue absorbing foam wedge sets as can be seen below. ====




 * On the lab computer, open the Power Panel 3.7 program. Verify that the power sensor is reading a signal. A typical reading is shown below.




 * On the lab computer, open the Antenna Controller program. If it opens without displaying any errors, then the cables are connected correctly and the program is capable of running a test.
 * Turn on the signal generator by flipping the switch labelled "POWER" on the front panel.
 * Open the Mini-Circuits Generator program.
 * From this window, select the large button labelled "USB Control", as seen below.




 * Click on each parameter and type in the desired values for Frequency and Power Out. **Note:** If a frequency value other than 2.4 GHz, is desired for a test, be sure to remove the 2.4 GHz bandpass filter from the power sensor before conducting the test.
 * Click "Apply".
 * The suggested values are shown below.




 * When you are ready to begin the test, make sure there is nobody standing inside the anechoic chamber, and make sure the signal generator has finished warming up. When the anechoic chamber is clear, and there is no indication of the "Warming Up!" message, click the "RF ON" button so the window appears as below. At this point, the transmit antenna is now transmitting the signal.




 * Follow the steps outlined below to measure the AUT characteristics.
 * **Phase 1: Initial Startup:** Open the Antenna Controller program. When the application is started, the following screen appears as can be seen below. Set the desired angle for the receive antenna to move during each measurement step. Then, provide a delay to occur between each movement of the antenna rotation. Once these two parameters are set, start the test by clicking “Start” on the right side, within the automated mode.




 * The table below shows a basic test time estimate for most combinations of step size and delay time. Use this table for reference when testing, especially if there are time constraints.




 * It is possible to stop and start the program at any point within the 360 degree rotation cycle. This immediately stops the rotation of the receive antenna. This feature is useful in case of a hardware malfunction or because the collected data does not need to be stored and analyzed. When you stop the program, you should see the pop-up as shown below.




 * **Phase 2: Post-Completion:** After the test has been completed, a dialog box stating “Completed!” is displayed. The results appear as shown below.




 * **Phase 3: Output Data File:** Location of data text file is in the same directory as the application. After each automated test, an output data file gets created automatically, regardless if the program was completed or interrupted by the user. The data file carries the name and extension formatted as: Month_Day_Year-Hour_Min_Angle.txt. The format of the recorded data file is as below:
 * The first column is the angle of rotation (in degrees).
 * The second column is the measured power from the sensor (converted to dBm).
 * There is a tab between the values.
 * After clicking "OK" on the "Completed!" dialog box, a gnuplot is automatically created using a gnuplot script written by Dr. Richie, using the recorded values in the text file.
 * To save the gnuplot, click on the "Save As..." icon in the toolbar in the window that appears with the gnuplot. This window is shown below. **Note:** Pressing "OK" or "Cancel" will remove the gnuplot, so it is important to save it first before closing that window.




 * At the conclusion of the test, unplug the stepper motor power plug to avoid the possibility of it overheating. Unless further testing will be done, remember to unplug the power sensor and stepper motor control cables and flip the switch labelled "POWER" on the signal generator to the "off" position.
 * An example of the antenna characteristics test is shown below. **Note:** The test shown in the video has the same process except the wooden pole has since been replaced by the turntable.

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

Roomba Robot Free-Space VSWR Test
For the free-space VSWR test, a Roomba robot is used to sweep a receive antenna across a set distance through the anechoic chamber. The Roomba moves forward in a straight line in 100 millimeter steps, stopping for about a second at each step, over a total of 700 millimeters. Upon reaching 700 millimeters, the Roomba then repeats this process going in reverse, returning to the original starting point. The wooden track for the Roomba can be placed in a range test configuration (towards/away from the transmit antenna) or an azimuth test configuration (perpendicular to the transmit antenna). Both of these testing configurations are detailed below. Also, below is a graphic of the overhead view of the different patterns the Roomba will need to move in order to complete a full free-space VSWR test.




 * ** Equipment Required: **
 * Mini-Circuits SSG-4000HP signal generator
 * Transmit antenna
 * Receive antenna
 * Agilent U2001A power sensor
 * Roomba robot
 * Arduino Uno R3 microcontroller
 * 8-foot by 4-foot wooden track
 * Blue absorbing foam wedges
 * Lab computer
 * ** Software Required: **
 * Power Panel 3.7
 * Mini-Circuits Generator
 * ** Procedure: **
 * If not done so already, set up the Roomba.
 * First, ensure that the Roomba is charged so it has enough battery to perform the free-space VSWR test. To do this, plug the charging cable into the port labelled with the symbol, ϟ.
 * **Note:** The Roomba will not charge and will beep intermittently if the cord connecting it to the Arduino is still plugged in. This is the beige cord and it must be disconnected in order to charge the Roomba's battery.
 * Ensure that wires coming out of the beige cord are properly connected to the Arduino board. Below is an image of the properly connected colored wires.




 * The green wire should be connected to pin 10 on the "Digital PWM" side of the Arduino.
 * The orange wire should be connected to pin 11 on the "Digital PWM" side of the Arduino.
 * The red and brown wire should be connected to the Vin pin on the "Power/Analog In" side of the Arduino.
 * The purple and blue wire should be connected to the GND pin on the "Power/Analog In" side of the Arduino.


 * When the Roomba is fully charged, connect the other end of the beige cord into the port directly above the charging port.
 * Ensure that the Arduino board is mounted onto the clear plastic mounting panel on top of the Roomba.
 * To mount the AUT, attach it to the bottle cap and coaxial cable configuration and feed the connected system into the through-hole of the Roomba, as shown below with the center-fed dipole antenna as an example.




 * After feeding it into the through-hole, use electrical tape to fix it to the top of the opening on top of the Roomba. The rest of the coaxial cable should be coming out of the bottom side of the Roomba, where it will be later connected to the power sensor.
 * The fully set up Roomba should resemble the image shown below, with the center-fed dipole antenna mounted as an example:




 * The next step is to set up the inside of the anechoic chamber. Follow the instructions below for each of the two different types of tests needed to complete the free-space VSWR test.
 * ** For the range (x-axis) test: **
 * First, unplug and remove the pedestal from the range, then cover the floor inside the anechoic chamber with blue absorbing foam wedges.
 * Begin setting up the blue absorbing foam wedges to serve as a base for the track by following the series of images as shown below. Keep in mind that it does not matter how high the individual blue absorbing foam wedges are stacked, it just matters that after it is fully assembled, the Roomba will be at the same height as the transmit antenna. This is a height of 4 feet, 7 inches.














 * After the track has been placed, position the Roomba on the far end of the track with regards to the transmit antenna, facing the transmit antenna. Make sure that the coaxial cable which is connected to the AUT and fed into the through-hole of the Roomba, is connected to the power sensor.
 * Place the power sensor in a position behind the track with regards to the transmit antenna to reduce potential interference. Place blue absorbing foam wedges to prop it up and prevent the coaxial cable from getting caught on the edge of the track.
 * Before starting the test, be sure that the USB cable from the power sensor is connected to the USB cable labelled "Power Sensor" as shown below. This connection will allow the lab computer to communicate with the power sensor.




 * Open the Power Panel 3.7 program on the lab computer. If the power sensor is connected, it should be reading the current power received in dB by the AUT.
 * Turn on the signal generator by flipping the switch labelled "POWER" on the front panel.
 * Open the Mini-Circuits Generator program.
 * From this window, select the large button labelled "USB Control", as seen below.




 * Click on each parameter and type in the desired values for Frequency and Power Out. **Note:** If a frequency value other than 2.4 GHz is desired for a test, be sure to remove the 2.4 GHz bandpass filter from the power sensor before conducting the test.
 * Click "Apply".
 * The suggested values are shown below.




 * When you are ready to begin the test, make sure there is nobody standing inside the anechoic chamber, and make sure the signal generator has finished warming up. When the anechoic chamber is clear, and there is no indication of the "Warming Up!" message, click the "RF ON" button so the window appears as below. At this point, the transmit antenna is now transmitting the signal.




 * At this point in the test, it is recommended that turning on the Roomba to begin the free-space VSWR test movement program, and starting the test itself, be coordinated between two people to happen at the same time. Otherwise, note that when the power button on the Roomba is pressed, it will wait 4 seconds before beginning its movement program. During this time, be ready to follow the steps outlined below to record the data.
 * In Power Panel 3.7, when the Roomba is about to begin its movement program, click on the "Strip Chart" symbol on the toolbar at the top of the window as shown below. After clicking on the "Strip Chart" button, the program will immediately begin recording values, so do this only after the Roomba has been turned on and is about to begin its movement program.




 * After the Roomba has completed its movement program, click on the red icon indicated below to stop recording data.




 * To save the recorded data, right-click on the strip chart and select "Save As..." to save it to a preferred destination.
 * The data is saved as a CSV file and can be manipulated with Microsoft Excel to make a graph.
 * An example set up of this configuration is shown below in the video. The video was taken while the signal generator was turned off.

media type="youtube" key="El3gwf-JMLg" height="480" width="854" align="center"


 * ** For the azimuth (y-axis) test: **
 * After performing the range test, disconnect the Roomba from the power sensor. Then, remove the Roomba, the wooden track, and all of the blue absorbing foam wedges other than those placed directly on the floor from the anechoic chamber.
 * Again, begin setting up the blue absorbing foam wedges to serve as a base for the track by following the series of images as shown below. Again, it does not matter how high the individual blue absorbing foam wedges are stacked, it just matters that after it is fully assembled, the Roomba will be at the same height as the transmit antenna. This is a height of 4 feet, 7 inches.












 * After the track has been placed, position the Roomba on the end of the track closest to the entrance of the anechoic chamber, facing away from the entrance. Make sure that the coaxial cable which is connected to the AUT and fed into the through-hole of the Roomba, is connected to the power sensor.
 * Follow the exact same steps as with the range test shown above. For reference, they are repeated below.
 * Place the power sensor in a position behind the track with regards to the transmit antenna to reduce potential interference. Place blue absorbing foam wedges to prop it up and prevent the coaxial cable from getting caught on the edge of the track.
 * Before starting the test, be sure that the USB cable from the power sensor is connected to the USB cable labelled "Power Sensor" as shown below. This connection will allow the lab computer to communicate with the power sensor.




 * Open the Power Panel 3.7 program on the lab computer. If the power sensor is connected, it should be reading the current power received in dB by the AUT.
 * Turn on the signal generator by flipping the switch labelled "POWER" on the front panel.
 * Open the Mini-Circuits Generator program.
 * From this window, select the large button labelled "USB Control", as seen below.




 * Click on each parameter and type in the desired values for Frequency and Power Out. **Note:** If a frequency value other than 2.4 GHz is desired for a test, be sure to remove the 2.4 GHz bandpass filter from the power sensor before conducting the test.
 * Click "Apply".
 * The suggested values are shown below.




 * When you are ready to begin the test, make sure there is nobody standing inside the anechoic chamber, and make sure the signal generator has finished warming up. When the anechoic chamber is clear, and there is no indication of the "Warming Up!" message, click the "RF ON" button so the window appears as below. At this point, the transmit antenna is now transmitting the signal.




 * At this point in the test, it is recommended that turning on the Roomba to begin the free-space VSWR test movement program, and starting the test itself, be coordinated between two people to happen at the same time. Otherwise, note that when the power button on the Roomba is pressed, it will wait 4 seconds before beginning its movement program. During this time, be ready to follow the steps outlined below to record the data.
 * In Power Panel 3.7, when the Roomba is about to begin its movement program, click on the "Strip Chart" symbol on the toolbar at the top of the window as shown below. After clicking on the "Strip Chart" button, the program will immediately begin recording values, so do this only after the Roomba has been turned on and is about to begin its movement program.




 * After the Roomba has completed its movement program, click on the red icon indicated below to stop recording data.




 * To save the recorded data, right-click on the strip chart and select "Save As..." to save it to a preferred destination.
 * The data is saved as a CSV file and can be manipulated with Microsoft Excel to make a graph.
 * An example set up of this configuration is shown below in the video. The video was taken while the signal generator was turned off.

media type="youtube" key="z9l_P-z6Tp8" height="480" width="854" align="center"