CST – Computer Simulation Technology

Bistatic Radar Cross Section: NASA Almond Benchmark

CST MICROWAVE STUDIO® (CST MWS) offers the facility to calculate the broadband radar cross-section (RCS) of arbitrary objects. The Time-Domain Solver in CST MWS can deliver the RCS results at arbitrary frequencies defined by the user - a tremendous advantage for RCS simulations. The ability of the time-domain solver to handle electrically large structures is also a major feature. The maximum dimension of the structure is about 10 wavelengths.

The geometry of the Almond is given in figure 1 with a plane wave excitation applied. The angle of incidence of the plane wave, the polarization of the field vector can be fully parameterized. The Almond is approximately 9.936 inches long and is defined as a Perfect Electrical Conductor (PEC). The dimensions of the Almond are given in equation form in References 1 and 2. These equations were used to create the geometry in CST MWS. ...



Figure 1: Almond Geometry with applied plane wave excitation

Figure 2 shows the comparsion between measured and simulated vertical component of RCS at 7 GHz.



Figure 2: Horizontal polarisation component of RCS against azimuth at 7 GHz

Figure 3 shows the comparsion between measured and simulated horizontal component of RCS at 7 GHz.



Figure 3: Vertical polarisation component of RCS against azimuth for excitation at 7 GHz

In a similar manner, the results for the vertical component of RCS at 1.19 GHz are shown in figure 4.



Figure 4: Vertical polarisation component of RCS at 1.9 GHz


Figure 5: Supperimposed E-Field Plane distributions at 9.92 GHz

Figures 5 and 6 show various field quatntites that can be extracted at any desired frequency from a single simulation run. In Figure 5, the electric fields on two orthogonal planes are superimposed. The surface current density is plotted in figure 6.



Figure 6: Surface Current distribution at 9.92 GHz

This article demonstrates the application of CST MWS to the broadband extraction of radar cross-section for electrically large structures. Just a single run is necessary for high resolution RCS data.

References

  • 1. A. K. Dominek, H. Shamanski, R. Wood, and R. Barger, "A Usehl Test Body," in Proceedings Antenna Measurement Techniques Association, September 24, 1986.
  • 1. A. K. Dominek and H. T. Shamanski, "The Almond Test Body," Report 721929-9, The Ohio State University Electro-Science Laboratory, Department of Electrical Engineering, prepared under Grant Number NSG1613, NASA Langley Research Center, March 1990

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