SWRA705 August   2021 AWR1243 , AWR1443 , AWR1642 , AWR1843 , AWR1843AOP , AWR2243 , AWR2944 , AWR6443 , AWR6843 , AWR6843AOP , AWRL1432 , AWRL6432 , IWR1443 , IWR1642 , IWR1843 , IWR2243 , IWR6243 , IWR6443 , IWR6843 , IWR6843AOP , IWRL6432 , IWRL6432AOP

 

  1.   Trademarks
  2. 1 Introduction and Challenges
  3. 2 Radome Design Elements
    1. 2.1 Understanding Dielectric Constant and Loss tangent on Radome and Antenna Design
    2. 2.2 Impedance Mismatch at Radome Boundaries
    3. 2.3 Radome Wall Thickness
    4. 2.4 Antenna to Radome Distance
  4. 3 Typical Radome Material Examples
  5. 4 Radome Angle Dependent Error
    1. 4.1 Rectangular Radome Angle Dependent Error
    2. 4.2 Spherical Radome Angle Dependent Error
    3. 4.3 Effect of the Angle Error in the Application
  6. 5 Radome Design and Simulations
  7. 6 Radome Lab Experiments
    1. 6.1 Radome Experiment – 1: Flat Plastic Radome
    2. 6.2 PTFE Material Rectangular Radome
    3. 6.3 PTFE-Based Curved Radome
  8. 7 Additional Considerations
    1. 7.1 Antenna Calibration
    2. 7.2 Radome Near Proximity Considerations
  9. 8 Summary
  10. 9 Acknowledgments
  11. 10References

7.1 Antenna Calibration

To improve antenna performance within a radome, SoC level antenna calibrations can be applied to compensate for bias in the range and receiver gain as well as phase introduced from the RF path delays. At a high level, the goal of this procedure is to determine the range bias offset common to all Tx-Rx paths and the gain and phase mismatch of each virtual Tx-Rx pair of a reference object placed at a fixed known distance in the far field at boresight. For more information on this subject, see [4].

The mmWave SDK provides a method for generating the calibration coefficients over the command line interface via the Out of Box (OOB) demo. For more details, see the mmWave SDK User’s Guide and look for the compRangeBiasAndRxChanPhase procedure. Additionally, the procedure and implementation of the calibration routine in the data-path processing chain can be found in the mmWave SDK install folder at: mmwave_sdk_<ver>\packages\ti\datapath\dpc\objectdetection\<chain_type>\docs\doxygen\html\index.html. You can use the OOB demo to perform the calibration or port the provided source code into your own custom application.

Additionally, using the same OOB demo application and reading sources, there is a procedure for removing near-field reflection from the air-radome boundaries. There can be antenna coupling signatures in the range bins close to the radar that manifest around DC in the range FFT output (see calibDcRangeSig in the SDK user's guide). The same calibration procedure can also be used to negate any near-field reflections caused by the radome.