a degree of openness of more than 90 can be achieved since the sheet segments 35 in this embodiment are essentially at right angles to the plane of the sheet 31 they will absorb a large part of the ir radiation which is not directed essentially downwards towards the bottom of the oven and a small part of the ir radiation which is directed to the bottom of the oven and thus towards foodstuffs which have been put into the oven for cooking thus since in this preferred embodiment we have made the grate with high porosity a small part of the ir rays which are directed towards foodstuffs in the oven will be absorbed while at the same time a relatively large part of the ir radiation which is directed towards the oven door for example is absorbed these absorption and permeability qualities provide two advantages firstly the grill elements will only to a very small extent contribute to raising the temperature of the oven door which reduces the risk of a user getting burned secondly by virtue of the absorbed ir radiation a high temperature zone is created in and around the grate which zone will burn splashes from the foodstuff which otherwise might hit the reflector and thus reduce its effectiveness with the right configuration.