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

2.3 Radome Wall Thickness

The wall thickness of the radome plays a key role in arriving at the optimum performance of the mmWave radar sensor. It is important to make sure that the radome wall thickness is equal to an integer multiple of the radar wavelength/2 so that the radome becomes “nearly transparent” for the mmWave frequency range intended. The thickness of radome is given in Equation 3. The wavelength in the radome material becomes shorter versus free air and is an inverse function of the material's dielectric constant as shown in Equation 4.

Equation 3. t o p t i m u m = n * λ m 2
Equation 4. λ m = C f * ε r

Where,

  • toptimum = Optimum thickness of radome wall or target thickness to make the radome transparent.
  • n: 1,2,3…
  • λm: Wavelength of the material
  • C: speed of light
  • f: mean carrier frequency used (for example, 62 GHz for a typical 60-64 GHz bandwidth)
  • εr : relative permittivity

In general, radome performance depends mainly on the frequency of use, thickness, εr, incident angle, and shape. For the normal incident case, optimum thickness given in Equation 4 is plotted in Figure 2-4 and Figure 2-5.

GUID-20210422-CA0I-JXWB-BFQD-RFKSFTVGSL6H-low.png Figure 2-4 Radome Optimal Thickness versus Dielectric for Incident Waves of Different Frequency
GUID-20210422-CA0I-35SH-VRCS-2JNZ12JTRRFS-low.png Figure 2-5 Radome Optimal Thickness versus Frequency for Different Dielectrics