Why are there two different outcomes when the electromagnetic parameters of the object are set to the output

[potatoess11]

Hello, developers：
I used a custom material setting function to modify the electromagnetic parameters of the target object：

     scattering_pattern1 = BackscatteringPattern(alpha_r=15,
                                                alpha_i=15,
                                                lambda_=0.8)
     set_materials_scene(scene, scattering_pattern1)
     scattering_pattern =BackscatteringPattern(alpha_r=param_dict['alpha_r'],
                                               alpha_i=param_dict['alpha_i'],
                                               lambda_=param_dict['lambda_'])
#param_dict is my dynamic parameter set
     print(f"alpha_r: {scattering_pattern.alpha_r}, alpha_i: {scattering_pattern.alpha_i}, lambda_: {scattering_pattern.lambda_}")
     # ===========================================
     set_materials_rcs(scene, param_dict,scattering_pattern)

def set_materials_rcs(scene, param_dict,scattering_pattern):
    scene.objects["car-itu_glass"].radio_material = "itu_glass"
    scene.objects["car-itu_glass"].radio_material.relative_permittivity=param_dict['relative_permittivity']
    scene.objects["car-itu_glass"].radio_material.thickness=param_dict['thickness']
    scene.objects["car-itu_glass"].radio_material.conductivity=param_dict['conductivity']
    scene.objects["car-itu_glass"].scaling = param_dict['scaling']  # 汽车尺寸
    scene.objects["car-itu_glass"].radio_material.scattering_pattern = scattering_pattern

    scene.objects["car-itu_metal"].radio_material = "itu_metal"
    scene.objects["car-itu_metal"].radio_material.relative_permittivity = param_dict['relative_permittivity']
    scene.objects["car-itu_metal"].radio_material.thickness=param_dict['thickness']
    scene.objects["car-itu_metal"].scaling = param_dict['scaling']
    scene.objects["car-itu_metal"].radio_material.scattering_pattern = scattering_pattern

and after the modification, I output two forms, one is a custom material parameter output function

 for f in frequencies:
        scene.frequency = f
        print(f"RadioMaterial: {so.radio_material.name} @ {scene.frequency/1e9}GHz")
        print("Conductivity:", so.radio_material.conductivity.numpy())
        print("Relative permittivity:", so.radio_material.relative_permittivity.numpy())
        print("thickness:", so.radio_material.thickness.numpy())
        print("Scattering coefficient:", so.radio_material.scattering_coefficient.numpy())
        print("XPD coefficient:", so.radio_material.xpd_coefficient.numpy())
        print("scaling：",so.scaling)
        print('=' * 50)

, and the other is：

 car_glass = scene.get("car-itu_glass")              
     car_metal = scene.get("car-itu_metal")
     itu_=car_glass.radio_material
     print("itu:",itu_)
     look_frequency = [fc]              
#===================================== 
     print_radio_material_properties(scene,car_glass, look_frequency,True)

What follows is a comparison of the two outputs：

itu: ITURadioMaterial type=glass
                 eta_r=20.000
                 sigma=1.000
                 thickness=0.001
                 scattering_coefficient=0.200
                 xpd_coefficient=0.100
RadioMaterial: itu_glass @ [3]GHz
Conductivity: [0.01568046]
Relative permittivity: [6.31]
thickness: [0.0005]
Scattering coefficient: [0.2]
XPD coefficient: [0.1]
scaling： 1.0
why the  eta_r=20.000
                 sigma=1.000 are not equal to     
Conductivity: [0.01568046]
Relative permittivity: [6.31]????

[jhoydis]

Hi @potatoess11,

The ITU materials set their parameters based on the frequency. So you cannot modify the properties.
What you are trying to do is to create a custom material. Please have a look at the corresponding developer guide.