Part 15: Analyze Radar Systems

This training requires additional licenses to complete. You can obtain the necessary license for the training by visiting http://licensing.agi.com/stk/evaluation or calling AGI support.

STK Radar

The Radar module allows users to build radar system models, to simulate their performance in mission scenarios, and to analyze their performance.

Agilent combined two industry-leading electronic design automation (EDA) tools, AGI's STK software and SystemVue from Agilent, to enable repeatable testing and hundreds of "what if" scenarios. You can read more in this case study: Reducing Flight Testing While Improving Effectiveness.

STK Radar also allows you to model an important characteristic of radar targets - radar cross section (RCS)- to calculate and display access and to generate reports and graphs of radar system performance.

Radar simulates both monostatic and bistatic radar systems and supports operations in Synthetic Aperture Radar (SAR) and/or Search/Track modes. Targets may be assigned multiple frequency-dependent radar cross sections to coincide with the various bands in operation in the scenario.

Model a Radar and Measure The Quality

  1. Create a new scenario (or skip to step 6 if continuing from the previous lesson).Closed
    1. Click the Create a new scenario () button.
    2. In the New Scenario Wizard, set the following options:
      • Enter a name for the scenario (e.g. STK_Radar).
      • Define the analysis start and stop times so that the stop time is three (3) days after the start time.
    3. Click OK.
  2. Update the Satellite Database.Closed
    1. Select the Basic - Database page.
    2. Click the Update Database Files... button.
    3. Enable the Specific Database option.
    4. Ensure the Database is set to stkAllTLE.
    5. Click Update.
    6. Click OK to close the information window.
    7. Click Close to close the Update Satellite Database window.
  3. Use Terrain Server for analysis.Closed
    1. Select the Basic - Terrain page.
    2. Enable the Azimuth/Elevation Mask in the Advanced Analysis Operations field.
    3. In the Advanced Analysis Options, enable Line-of-Sight, Terrain Mask, Azimuth-Elevation Mask, and Coverage.
    4. Click OK.
  4. Insert a facility that acts as a radar site.Closed
    1. Insert a facility using the Insert Default method.
    2. Rename the facility (e.g. Radar_Site).
    3. Open Radar_Site's () properties ().
    4. In the Basic - Position page, make the following changes:
      • Latitude: 30.5301 deg
      • Longitude: -86.2135 deg
    5. Select the Basic - AzElMask page.
    6. Make the following changes:
      • Use: Terrain Data
      • Enable Use Mask for Access Constraint
    7. Click OK.

Use the Deck Access Tool to determine satellites in the radar's field-of-view.

  1. Insert a sensor that mimics the radar system field-of-view.Closed
    1. Insert a sensor () using the Insert Default method.
    2. Attach a sensor () object to Radar_Site ().
    3. Rename the sensor (e.g. Radar_FOV).
    4. Open Radar_FOV's () properties ().
    5. In the Basic - Definition page, make the following changes:
      • Sensor Type: Rectangular
      • Vertical Half Angle: 50 deg
      • Horizontal Half Angle: 60 deg
    6. Click Apply.
    7. Select the Basic - Pointing page.
    8. Make the following changes:
      • Azimuth: 180 deg
      • Elevation: 50 deg
    9. Click Apply.
    10. Select the Constraints - Basic page.
      • Set Range - Max to 22000 nm.
      • Enable the Az-El Mask option.
    11. Click Apply.

      12. The system can track satellites 60 degrees on either side of the sensor center line which provides 120 degrees of azimuth coverage. The sensor has 100 degrees of vertical coverage. The sensor points south (azimuth 180 degrees) and an elevation of 50 degrees slants the sensor allowing for the vertical coverage. Finally, the system is designed to track satellites out to a distance of 22,000 nautical miles.

    12. Select the 3D Graphics - Attributes page.
    13. Set the Projection - % Translucency to 90.
    14. Click OK.
  2. Determine which satellites fly through the sensor's field-of-view.Closed
    1. In the Object Browser, right-click on Radar_FOV and select Deck Access.
    2. When the Deck Access Tool opens, set the Input - Stop to one (1) minute. This samples the satellite database for one minute.
    3. Click the ellipsis button and select stkAllTLE.tce in the Select Target Deck field.
    4. Click Compute Accesses.

      5. When the report is completed, you can scroll through the report. Numerous satellites are seen for the full 60 seconds time period. Most likely these are geosynchronous satellites. Using Celestrak, you can search satellites by their Name (NORAD Catalog Number). Disable filters to ensure you get a hit.

    5. When finished, close the report and the Deck Access tool.

Model the Target and the Radar.

  1. Insert a satellite that has a large radar cross section (RCS).Closed
      1. Insert a Satellite using the From Standard Object Database method.Closed
        1. Insert a Satellite using the From Standard Object Database method.
        2. Enter 25544 (International Space Station) as the Name or ID.
        3. Click Search.
        4. Select ISS (ZARYA).
        5. Click Insert.

        When you use AGI's Online Database to insert the ISS, the orbit may appear jagged. This is because the orbit step size is set to 300 sec. If you would like a smoother appearance to the orbit, change the step size to 60 seconds.

      2. Apply a realistic Radar Cross Section to the Satellite.Closed
        1. Open ISS_ZARYA_25544's () Properties ().
        2. Select the RF - Radar Cross Section page.
        3. Disable the Inherit option.
        4. Set the Swerling Case to IV.

          5. Swerling Case IV probability density function approximates an object with one large scattering surface with several other small scattering surfaces. The RCS varies from pulse rather than from scan to scan.

        5. Set the Constant RCS Value to 402 sqm.
        6. Click OK.
  2. Insert a radar that is constrained to the sensor's field-of-view.Closed
    1. Insert a radar using the Insert Default method.
    2. Attach the Radar object to Radar_FOV ()
    3. Rename the Radar (e.g. ISS_Tracker).
    4. Open ISS_Tracker's properties.
    5. Select the Pulse Integrated tab.
    6. Change the Goal SNR to Fixed Pulse Number.
    7. Set the Pulse Number to eight (8).
    8. Click Apply.
    9. Select the Antenna tab and set the following:
      • Set the Type to Phased Array.
      • Set the Number of Elements to x=7; y=7.
    10. Click Apply.
    11. Select the Beam Direction Provider tab and make the following changes:
      • Enable the Beam Steering option.
      • Move () ISS_ZARAYA_25544 to the Selected List.
    12. Select the Transmitter tab and make the following changes:
      • Set the Wavelength to 68 cm.
      • Set the Power 370 kW. Each antenna element receives power from a separate transmitter module having an output power of 10 kW.
    13. Click Apply.
    14. Select the Receiver tab.
    15. Set the LNA Gain to 20 dB which simulates the post pulse compression gain.
    16. Click Apply.
  3. Constrain the Radar.Closed
    1. Select the Constraints - Basic page.
    2. Enable the Field-of-view and Az-El Mask options.
    3. Click Apply.

      4. The Radar object is a child of the sensor object, which is a child of the Facility object. By enabling Field-of-view and Az-El Mask, any reports or graphs using the Radar object will be restricted to the Facility object's AzElMask and the Sensor object's field-of-view. This is a quick way to set access constraints to the Radar object. However, if you require a more realistic setup that might take interference into consideration, this setup wouldn't be optimal since all access is restricted to the sensor object's field-of-view.

  4. Visualize the antenna pattern.Closed
    1. Select the 3D Graphics - Attributes page.
    2. Enable the Show Volume option in the Volume Graphics field.
    3. Enable the Show as Wireframe option.
    4. Set the Gain Scale (per dB) to one (1) km.
    5. Set the Gain Scale Offset to negative ten (-10) dB.
    6. Enable the Set azimuth and elevation together option.
    7. Set the Azimuth Resolution to 0.5 deg.
    8. Click OK.
    9. Bring the 3D Graphics window to the front.
    10. Zoom To to Radar_Site .
    11. Zoom In or Out to view the antenna pattern.

Track the International Space Station

  1. Create a Probability of Detection Graph to determine when you can detect the ISS.Closed
    1. Right-click ISS_ZARAYA_25544 () and select Access ().
    2. Expand Radar_Site and then expand Radar_FOV.
    3. Select ISS_Tracker ().
    4. Click the Report & Graph button.
    5. Create a custom graph that shows the integrated probability of detection and the probability of detection.Closed
      1. Right-click on the MyStyles directory.
      2. Extend the New menu and select Graph.
      3. Rename the graph PDET.
      4. Click Enter on the keyboard to open PDET's properties.
      5. Expand the Data Provider called Radar SearchTrack.
      6. Move () S/T Integrated PDet to the Y-Axis.
      7. Move () S/T PDet1 to the Y2-Axis.
      8. Click OK.
      9. Generate the custom PDet graph.

    A search track value greater than 50% is acceptable for probability of detection (S/T PDet1 = 0.50).

Don't forget to save your work!

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