What angular increment should be used for RCS with MLFMM?

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

When using the MLFMM for the computation of monostatic RCS values, for each new angle of incidence of the plane wave an iterative solution must be performed. Accelerations were implemented in FEKO to use the phase corrected solution from the previous angles of incidence as start value for the subsequent iterations. This acceleration greatly reduces the number of required iterations and therefore the overall runtime. The question is what angular increment should be used to best make use of this feature?

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    Could you show by using an example?

  • JIF
    JIF
    Altair Employee
    edited June 2017

    The far-field phase is given by

    exp( -i*k*d*sin(theta) ) = exp( -i*2*pi *(d/lambda) * sin(theta) )

     

    Take a for example a car model where where d=4.67 m is the length of the car solved at 5 GHz (lambda=0.0666 m.)

    This gives d/lambda = 70.12.

    We need at least 4 samples for every 2*pi, therefore:

    (d/lambda)*sin(theta) = 0.25

    This gives a minimum phase increment for the plane wave as follows:

    theta = asin(0.25 / (d/lambda) ) = 0.2 degrees

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2018

    Hi Jif - I'm not familiar with this equation. Could you provide a reference to where this equation comes from?

  • JIF
    JIF
    Altair Employee
    edited July 2018

    Take a look at Figure 1 in the following post. The explanation is about grating lobes, but the ideas are the same.

     

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