Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented.

/pdf/defected-ground-structure-fundamentals-analysis-and-27vyawjqvf.pdf

Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

This letter presents a microstrip patch antenna integrated with two-dimensional photonic bandgap (PBG) and one-dimensional defected ground structure (DGS) jointly in ground plane. It is demonstrated that application of both PBG and DGS eliminates the second and third harmonics and improves the return loss level. Moreover, the combination use of PBG and DGS decreases the occupied area by 70% compared to the conventional PBG patch antenna.

Harmonic suppression with photonic bandgap and defected ground structure for a microstrip patch antenna

Defected ground structures (DGS) have been developed to improve characteristics of many microwave devices. Although the DGS has advantages in the area of themicrowave filter design, microwave oscillators, microwave couplers to increase the coupling, microwave amplifiers, etc., it is also used in the microstrip antenna design for different applications such as antenna size reduction, cross polarization reduction,mutual coupling reduction in antenna arrays, harmonic suppression etc., TheDGS ismotivated by a study of Photonic/Electromagnetic Band gap structures. The etching of one or more PBG element creates defect in the ground plane and used for the same purpose. The DGS is easy to be an equivalent L-C resonator circuit. The value of the inductance and capacitance depends on the area and size of the defect. By varying the various dimensions of the defect, the desired resonance frequency can be achieved. In this paper the effect of DGS, to the different antenna parameter enhancement is studied. Index Terms – Defected Ground Structure, Microstrip Antennas.

Defected Ground Structure in the perspective of Microstrip Antennas: A Review

A defected ground structure (DGS) is used to suppress mutual coupling between elements in a microstrip array and eliminate the scan blindness in an infinite phased array. Two kinds of DGSs, namely back-to-back U-shaped and dumbbell-shaped DGSs, are analysed and compared. The analysis indicates that the back-to-back U-shaped DGS is better at suppressing propagation of surface waves in microstrip substrate. A two-element microstrip array with back-to-back U-shaped DGS is designed and the array characteristics against different element distances are studied. The results show that the degree of the mutual coupling suppression is increased when the element distance is reduced. However, compared with the traditional array, a higher gain and lower side lobes are obtained when a larger element spacing is selected. The scan blindness of an infinite microstrip phased array in E-plane is studied by simulation, and the calculation demonstrates that the scan blindness can be eliminated by applying a back-to-back U-shaped DGS to the infinite phased array.

Mutual coupling suppression in microstrip array using defected ground structure

In this paper, an effective approach for mitigating the near-field coupling between four-port circularly polarized (CP) antennas in a 30-GHz multiple-input, multiple-output (MIMO) system is suggested and investigated. This is obtained by incorporating a two-layer transmission-type frequency selective surface (FSS) superstrate based on planar crossed-dipole metal strips. This paper presents a comparison between the mutual coupling when the patches are radiating in free space and in the presence of the FSS layers. The simulated results, when the FSS layers are applied, show an average of 6–12-dB improvement in the isolation between four adjacent CP-MIMO antennas. In addition, an accurate study is carried out on the insignificant reflections produced by the FSS layers to redirect those and also prevent any interference. The proposed $2\times 2$ CP-MIMO antenna along with the superstrate is implemented and tested to validate the simulation results. Experimental results of the coupling and reflection coefficients and axial ratio show an acceptable agreement with the corresponding simulated ones.

Spatially Decoupling of CP Antennas Based on FSS for 30-GHz MIMO Systems

A new defected ground structure (DGS) consisting of concentric circular rings in different configurations is experimentally studied to examine the stopband characteristics. Unlike previous DGS designs, a metallic shielding is introduced at the back of the DGS to suppress any leakage or radiation, and this would be advantageous for microwave circuit applications. A wide stopband is demonstrated with a set of prototypes designed for X-band. Its application to suppressing mutual coupling in microstrip patch arrays is demonstrated

Concentric Ring-Shaped Defected Ground Structures for Microstrip Applications

In this paper, we have presented a comprehensive review of research on microstrip antennas conducted at the Institute of radio Physics and Electronics, University of Calcutta with an emphasis to those done in recent years.

S. Biswas

Papers

Concentric Ring-Shaped Defected Ground Structures for Microstrip Applications

Microstrip radiating structures: Theoretical and experimental investigations executed in recent years at the University of Calcutta