Design of a novel bandstop filter using log periodic based circular split ring slots

Compact planar microstrip bandstop filters are introduced here. These filters consist of log-periodic based 3 resonator elements. These defects or slots on the signal plane effecting resonant frequency of the filters due to increment of slow wave factor, which exhibits good bandstop characteristics. The filters can be designed to function in a low frequency to a very high frequency range depending upon the physical dimension of the slots. When the filters are designed at lower frequency, the guided wavelength is increased by increasing the radius of the split ring slots and vice versa. First of all a unit cell is investigated. A set of circular split ring slots are designed to achieve stopband of the filter at desired frequency range.