Magnitude of Fundamental Mode

AM_20700
AM_20700 Altair Community Member
edited March 2023 in Community Q&A

Hello,

I am very new to FEKO, and I am not an electrical engineer. So please ELI5.

When defining a waveguide source, what is the "Magnitude (W)^1/2"  in the "Fundamental Mode" options?

If I am trying to simulate a rectangular waveguide, with a 75 kW wave propagating through it, how is the appropriate "Magnitude" value calculated?

Do I need to calculate the average power density by dividing the wave power by the waveguide cross-section area, then calculate the magnitude of the electric field (E0) from the equation: S = (c*e0*E0^2)/2 ?

So if the cross-section area is 0.044 m^2, then the average power density is 1.69 MW/m^2, and E0 is 35.7 kV/m?

If the 75 kW is the peak power of the wave, do I need to divide the peak power by 2 in order to get the average power, and then use the average power to calculate the average power density?

Thanks.

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Answers

  • Jaehoon
    Jaehoon
    Altair Employee
    edited March 2023

    what is the "Magnitude (W)^1/2"  in the "Fundamental Mode" options?

    -> The expression means the magnitude of the mode is the same dimension of the (E/H) field whose value is proportional to the square root of power. (The power is defined in Power settings.)

    Sorry, I don't fully follow your calculation, but the power in the waveguide cross-section should be calculated from E and H field and their cross-section. It might be easy to understand the flowing power with a rectangular waveguide excited by TE10 mode.

    Thank you.

  • AM_20700
    AM_20700 Altair Community Member
    edited March 2023
    Jaehoon Kim_22316 said:

    what is the "Magnitude (W)^1/2"  in the "Fundamental Mode" options?

    -> The expression means the magnitude of the mode is the same dimension of the (E/H) field whose value is proportional to the square root of power. (The power is defined in Power settings.)

    Sorry, I don't fully follow your calculation, but the power in the waveguide cross-section should be calculated from E and H field and their cross-section. It might be easy to understand the flowing power with a rectangular waveguide excited by TE10 mode.

    Thank you.

    Thanks.

    I was referring to this equation for intensity or average power density:
    image

    I know the power that is being pumped into the waveguide, so I divided the power by the cross-section area to get the average power density. Then I used the above equation to find the amplitude of the electric field (E0).

    Should I leave the "Magnitude" as default (1), and set the "Power" value to 75 kW?

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