Consideration of Engineered Ground Planes for Planar Antennas: Their Effects and Applications, a Review

Abstract

In this article, the significance of engineered ground planes in microstrip antennas and the effects of various configurations for the enhancements of the characteristics like isolation, cross-polarization levels, bandwidth and size reduction are vividly analyzed. These defects are classified and compared based on different applications and some important conclusions have been derived to infer a clear idea about its implementations as well as design considerations. The basic objective of this article is to motivate the readers and make them understand how this simple technique can be utilized to achieve various complex requirements of antennas needed for many contemporary as well as upcoming technologies like 5G, massive MIMO, IoT, Millimeter-wave communications by taking care of all the above parameters.INDEX TERMS compact, DGS, harmonic, multiband, wideband. I. INTRODUCTION F OR two decades there always has been an accelerating demand, in both commercial and the defence sectors, for antennas with various desirable attributes like compact size, easy to fabricate, multi-band or broadband, higherorder harmonic suppression and enhanced radiation properties. Multiple approaches have evolved over the years, among which the engineered ground planes, popularly known as defected ground structures (DGS) have been utilized most effectively to accomplish one or more of these design attributes. The application of electromagnetic bandgap (EBG) or photonic band-gap (PBG) structures are very common in microwave filters, couplers and antennas due to their bandstop characteristics that prohibit the propagation of electromagnetic waves in a specific frequency range. DGS is a special class of EBG structures that have a well governable transmission zero characteristic and this is managed by introducing necessary filtering actions through etching. In this article, a comprehensive analysis of various engineered ground planes used in microstrip antennas are presented. Different types of ground perturbation techniques, their chronological adavancements, effects of the shapes on different parameters and their applications are summarized. The prime objective of this article is to introduce this fascinating technique to the designers and guide them in selecting appropriate ground alteration technique to achieve desired antenna performance. 28 II. ENGINEERED GROUND PLANES: THE CONCEPT 29 EBG structures, the origin of DGS [1]; are artificial periodic 30 structures of metallic [2], dielectric [3] bodies with a lattice 31 period λ g /2 and exhibit a peculiar characteristic of allowing 32 the EM wave to propagate through a range of frequencies 33 (pass-band) while restricting the propagation over a range 34 called stop-band. Generally, a microstrip transmission line 35 shows bandpass characteristics whereas a microstrip line 36 placed on an artified ground plane shows stopband(s) in its 37 transmission characteristics. Any deformity created in the 38 ground plane of the microstrip line/antenna alters its current 39 distribution and thus increa...

Planar Printed Structures Based on Matryoshka Geometries: A Review

“…DGSs have been used in microstrip antenna implementations to provide multiband and/or wideband behavior, improve gain and cross-polarization, and suppress higher order modes and mutual coupling (in arrays) [70][71][72][73][74]. Many different shapes of the DGS slots have been used, ranging from canonical geometries (rectangular, triangular, circular) to non-canonical (Hshaped, dog bone-shaped) [75]. Recently, such variety was enhanced with the Matryoshka geometry [25,28].…”