Multiband EMI filter based on metamaterials

A novel compact multiband microstrip EMI filter based on metamaterials is presented. The filter is implemented by means of split-rings resonators and complementary spiral sub-wavelength resonators, conveniently coupled to the victim transmission line. The suitable combination of these resonators allows us to design several stop-band frequency responses located at 900MHz (RFID UHF), 1.8GHz (GSM) and 2.4GHz (ISM) with a significant rejection level. A 3-stages/5-stages rejection band filter has been designed and fabricated in a PCB. The experimental results show a significant rejection level in agreement with the electromagnetic simulations