Investigation into Narrower Slot of Dumbbell Shape Defected Ground Structure Under a Standard Microstrip T-Line

Abstract

Electromagnetic Band Gap Structures (EBGSs) delivered a wide assortment of plan choices for specialists working in the territory of microwave and photonics. The spotlight is currently towards on discovering genuine applications. Because of the unbelievable capability of EBGSs, there are enormous applications in which they can be utilized. This thesis describes the planar EBG structures in the forms of conventional circular and rectangular EBGSs and dumbbell-shaped defected ground structures (DS-DGSs). Conventionally, the DS- DGS consists of two bigger slots and a narrower slot. Here the shape of narrower slot of dumbbell shape DGS has been focused. Modified EBGS in the form of changing the gap height of narrower slots of dumbbell-shaped DGS cells has been studied. These modified DGSs provide wide stopband properties. The DS-DGSs study has been carried out with the investigation into narrower slots and their properties. Some modified designs have been proposed such as; changing the height and width of the narrower slot of the dumbbell-shaped DGSs we have seen the performance. We have also increased the number of narrower slot to see the performance. The modified designs perform better than the conventional DGSs reported in the open literature. The proposed DGSs yield lowpass filter (LPF) properties with good passband and amazingly wide stopband. In this thesis, uniform circular and rectangular with different filling factor (FF) and DS-DGS with similar periodicity like circular or rectangular structure have investigated. Then for the better performance, we have focused on narrower slot of the DS-DGSs. This research conveys the performance of filter at about 4 GHz cutoff frequency. These distributions remove the unwanted spurious transmission in the band rejection region. It is seen that in the dumbbell shape DGS the number of the narrower slot has a significant role to control the depth and width of the stopband. Besides, the optimized design is achieved by varying the height of the narrower slot. For two narrower slots, it provides the best performance. The optimized design has the size of the larger slot of 5.22×5.22 sq mm and the narrower slot is 0.78×0.75 sq mm. The proposed DSDGS with two narrower slots is suitable for lowpass filter implementation. Finally, the insertion loss (IL) and return loss (RL) performances of different designs have been compared. It is seen that our modified designs provide improved performance and more compactness in terms of return and insertion-loss bandwidths. The sufficient explanations have been provided to validate the total research works.