Effects of a Lumped Element on DGS with Islands

In this paper, the effects of a lumped element on a DGSI (defected ground structure with islands), which consists of some islands around the microstrip signal line on the upper plane, are investigated. In order to demonstrate the effects of the lumped element which is placed at the islands section on the upper plane, a parallel resonator with the dumbbell-shaped DGSI is proposed and implemented. A chip resistor and capacitor are chosen as lumped elements for the verification. Experimental results show that the Q-factor and resonant frequency of the proposed DGSI can be controlled directly by using the external lumped element