A microwave device is based on gap waveguide technology, and comprises two conducting layers (101, 102) arranged with a gap there between, and protruding elements (103, 104) arranged in a periodically or quasi-periodically pattern and fixedly connected to at least one of said conducting layers, thereby forming a texture to stop wave propagation in a frequency band of operation in other directions than along intended waveguiding paths. Sets of complementary protruding elements are either each formed in said pattern and arranged in alignment and overlying each other, the complementary protruding elements of each set forming part of the full length of each protruding element of the pattern, or the sets of complementary protruding elements are arranged in an offset complementary arrangement, the protruding elements of one set thereby being arranged in between the protruding elements of the other set.