Part 15: Analyze Radar Systems

Required Licenses:

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

Lesson 15.1: STK Radar

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

Case Study
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.

Task 1: Model a Radar and Measure The Quality

  1. ClosedCreate a new scenario (or skip to step 6 if continuing from the previous lesson).
    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 or accept the defaults.
    3. Click OK.
  2. ClosedDisable Terrain Server.
    1. Open the scenario's () properties ().
    2. Select the Basic - Terrain page.
    3. Disable the Use terrain server for analysis option.
    4. Click OK.
  3. ClosedInsert a satellite () that has a large radar cross section (RCS).
      1. ClosedInsert a Satellite using the From Standard Object Database method.
        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.
      2. ClosedApply a realistic Radar Cross Section to the Satellite.
        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.

        6. Set the Constant RCS Value to 402 sqm.
        7. Click OK.

AGI-ers Say
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.
AGI-ers Say
The duty cycle of a radar is the ratio of the pulse width to the pulse-repetition period. The default value for Pulse Width is 0.1 microseconds.
Did You Know?
You can use an external Aspect Dependent RCS file (*.rcs) to define the radar cross section for a track. Several example files are available in this directory: (<STK install folder>\Help\STK\text).

Task 2: Create a Radar site that has three separate faces, each scanning a 120 degree azimuth and an elevation of two (2) degrees to 89 degrees.

  1. ClosedInsert a place () object using the City Database.
    1. Using the City Database, search for the city Omaha.
    2. When the search results appear, select Omaha, Nebraska.
    3. Click Insert.
  2. ClosedInsert a radar () object using the Default method and set it's properties.
    1. Attach a radar () to Omaha ().
    2. Rename the Radar object 0_120deg.
    3. Open 0_120deg's () Properties ().
    4. Select the Basic - Definition page.
    5. Select the Antenna tab.
    6. Select the Model Specs tab.
    7. Set the Type to Phased Array.
    8. Select the Element Configuration tab.
    9. Set the Number of Elements to (X: 39; Y: 39).
    10. Select the Beam Direction Provider tab.
    11. Ensure Beam Steering is enabled.
    12. Move () ISS_ZARYA_25544 to the Selected list.
    13. Select the Transmitter tab.
    14. Enable the Frequency option and set it to .35 GHz.
    15. Set the Power to 60 dBW.
    16. Click Apply.
  3. ClosedConstrain the radar.
    1. Select the Constraints - Basic page.
    2. Set the Min value for the Azimuth Angle option to zero (0) deg.
    3. Set the Max value for the Azimuth Angle option to 120 deg.
    4. Set the Min value for the Elevation Angle option to two (2) deg.
    5. Set the Min value for the Elevation Angle option to 89 deg.
    6. Click OK.
  4. ClosedReuse the Radar object and reorient the fields-of-view.
    1. Select 0_120deg () radar and click the Copy () button.
    2. Select Omaha () and click Paste () twice.
    3. Rename one of the new Radar objects 120_240deg and other radar to 240_360deg.
    4. Open 120_240deg's () properties ().
    5. Select the Constraints - Basic page.
    6. Set the Min value for the Azimuth Angle option to 120 deg.
    7. Set the Max value for the Azimuth Angle option to 240 deg.
    8. Click OK.
    9. Open 240_360deg's () properties ().
    10. Set the Min value for the Azimuth Angle option to 240 deg.
    11. Set the Max value for the Azimuth Angle option to 360 deg.
    12. Click Apply to accept the changes and keep the Properties Browser open.
  5. Save () your scenario.
  6. ClosedVisualize the antenna pattern.
    1. Bring the Properties for 240_360deg () to the front.
    2. Select the 3D Graphics - Attributes page.
    3. Enable the Show Volume option in the Volume Graphics field.
    4. Enable the Show Wireframe option.
    5. Set the Gain Scale (per dB) to 0.1 km
    6. Set the Gain Scale Offset to ten (10) dB.
    7. Enable the Set azimuth and elevation resolution together option.
    8. Set the Azimuth Resolution to 0.5 deg.
    9. Set the Azimuth Start to -120 deg and the Stop to zero (0) deg.
    10. Set the Elevation Start to one (1) deg and the Stop to 88 deg.
    11. Click OK.
    12. By changing the azimuth and elevation values, you see the sector that antenna is covering.

  7. ClosedBring the 3D Graphics window to the front and Zoom To Omaha ().
    1. Zoom In or Out to view the Antenna pattern.
    2. When finished, open 240_360deg's () properties () and disable the Show Volume option.
    3. Click OK.

Task 3: Track the International Space Station.

  1. ClosedIn the Object Browser, right-click ISS_ZARYA_25544 () and select Access ().
    1. Expand Omaha () and select all three radar () objects.
    2. Click the Report & Graph button.
  2. ClosedCreate a custom graph that shows the probability of detection (PDET).
    1. In the Object list, only select one of the three accesses. (ex. Satellite-ISS_ZARYA_25544-To-Place-Omaha-Radar-0_120deg only).
    2. Right-click on the MyStyles directory.
    3. Extend the New menu and select Graph.
    4. Rename the graph, PDET.
    5. Expand the Data Provider called Radar SearchTrack.
    6. Select S/T PDet1 and Move it to the Y-axis.
    7. Click OK.
    8. In the Objects List, multi-select all three (3) accesses.
    9. Select the PDET custom graph and click Generate.
    10. On the graph, you can zoom in to one of the tracking periods. You can determine if only one or multiple faces of the radar site track the ISS.

AGI-ers Say
A search track value greater than 50% is acceptable for probability of detection (S/T PDet1 = 0.50).
Warning
Don't forget to save your work!
Bonus

Here are some additional related resources, if you would like to learn more: