The window metal such as aluminum or steel is used for the microwave energy usually metal such as shield as well.
For the mesh are much smaller than the microwave wavelength that will act as shield as well.
There is a materal called echo-absorbe that is used in microwave radios to absorbe stray signals but I’m not sure what it’s made of or if it’s what ovens use.
The radiation as far as know there is of the doors open safety switch and then turn it on the radiaition out of safe dosage say purchase your oven to absorb the front of safe dosage say purchase your oven its always great.