However , in practice they can be caused by poorly mating waveguide flanges or misaligned teeth .
TE modes should not , in theory , be excited in the waffle - iron filter because of its vertical symmetry about the centre - line .
In practice they can be caused by poorly mating waveguide flanges or misaligned teeth .
TE modes should not , in theory , be excited in the waffle - iron filter because of its vertical symmetry about the centre - line .