An Introduction to Defected Ground Structures in Microstrip Circuits

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  • Author: Gary Breed
In recent years, there have been several new concepts applied to distributed microwave circuits. One such technique is defected ground structure or DGS, where the ground plane metal of a microstrip (or stripline, or coplanar waveguide) circuit is intentionally modified to enhance performance. The name for this technique simply means that a “defect” has been placed in the ground plane, which is typically considered to be an approximation of an infinite, perfectly-conducting current sink. Of course, a ground plane at microwave frequencies is far removed from the idealized behavior of perfect ground. Although the additional perturbations of DGS alter the uniformity of the ground plane, they do not render it defective.