A bandstop filter using a new defected microstip and Defected Ground Structures

A Slot on a strip called defected microstrip structure (DMS) makes a defect on the circuit which can be used in designing filters, power dividers etc. This defect creates resonance characteristics in the frequency response. This kind of structure is constructed by removing pattern etched from the top conductor of microstrips and can be used as a band stop filter. In this paper the introduction of a new spiral type Defected Microstrip Structures is presented. The frequency characteristics of the proposed spiral-shaped DMS unit show one pole stopband response. The equivalent L-C parameters are extracted using the proposed equivalent LC model. Like a T type DMS, the pi type DGS structure also provides high value of slow wave factor. The combination of Defected Ground and Defected Microstrip Structures is proposed to improve the performance of filters. The DMS is advantageous in high frequency designs and millimeter wave applications.