Radar Cross Section and Surface Current Simulation for a Helicopter
This article demonstrates the simulation of an electrically large helicopter. The length of the helicopter is about 7.8 meters and, therefore, the aircraft is approximately 180 wavelengths in size. The helicopter is illuminated by a plane wave at 7 GHz and is simulated using the new Integral Equation solver (I-solver) of CST MICROWAVE STUDIO® (CST MWS). The I-solver features a discretization by the Method of Moments using a surface integral formulation of the electric and magnetic field integral equations combined with the Multilevel Fast Multipole Method (MLFMM). Due to the surface integral formulation the new solver uses much fewer mesh cells than common volume methods. Moreover, as a result of the MLFMM the solver shows numerically an efficient complexity in operations and memory for electrically large structures, and it is very accurate compared with standard simulation techniques.
For the presented helicopter which is totally made of PEC the surface mesh is about 830.000 surface cells. Accordingly, the simulation is performed using more than 1.25 million unknowns.
Figure 1 displays the geometry of the simulated helicopter.
Figure 1: The geometry of the helicopter from the front and the side
Figure 2 shows the plane wave illumination of the helicopter at 7 GHz. The electric field vector for the plane wave excitation points into the vertical direction.
Figure 2: Plane wave illumination from the front at 7 GHz
The next figures show the RCS farfield results for the helicopter. Figure 3 displays the three-dimensional RCS farfield in spherical polar coordinates with a maximal RCS of 53.01dBsm. Figure 4 shows the RCS field in polar coordinates as a function of the spherical angle theta (left) and as a function of phi (right).
Figure 3: Three-dimensional spherical RCS farfield plot of the helicopter
Figure 4: RCS farfield as a function of theta (left) and phi (right)
Figure 5 and 6 show the calculated absolute values for the surface current on the helicopter. Figure 5 (right) displays the surface current when zooming into the structure. Figure 6 shows an animation of the surface current of the detailed region of the helicopter shown in Figure 5 (right). To display the animation please check the advanced settings in your browser and refresh the current view.
Figure 5: Surface currents on the helicopter
Figure 6: Phase animation of the surface current on the helicopter
This article demonstrates the ability of CST MWS to simulate electrically large structures with the Integral Equation solver. Due to the applied Method of Moments combined with the efficient MLFMM within the I-solver the results are very accurate. Also the used memory for more than 1.25 million unknowns shows the efficiency of this new solver. In comparison, standard solvers using Method of Moments might need more than one terabyte of memory for these type of electrically large structures.
CST Article "Radar Cross Section and Surface Current Simulation for a Helicopter"
last modified 21. Mar 2007 4:03
printed 4. Jul 2008 3:27, Article ID 287
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Article ID: 287
Last modified: 21. Mar 2007 4:03
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