Very compact broad band-stop filter using periodic L-shaped stubs based on self-complementary structure for X-band application

Self-complementary structures are used to design a novel compact band-stop filter for X-band applications. By cutting a rectangular slot with five pairs of L-shaped protruded strips inside the slot on the ground plane and by inserting five pairs of L-shaped stubs in the microstrip transmission line, the self- complementary structure is created, hence a constant and flat impedance bandwidth at the X-band can be produced. The operating frequencies of the filter can be easily controlled by changing the dimensions of the protruded L-shaped strips and stubs, without changing the area taken up by the structure. Experimental results show good agreement with simulation results and demonstrate that excellent stop-band performance could be obtained through the proposed band-stop filter.