Design methodology for sievenpiper high-impedance surfaces: an artificial magnetic conductor for positive gain electrically small antennas

Abstract

The Sievenpiper high-impedance surface is a periodic structure characterized by a substrate filled with an array of vertical vias, capped by a capacitive frequency selective surface (FSS). It functions as the ideal antenna groundplane for wireless applications because it simultaneously enhances the gain of the antenna as it suppresses the surface waves associated with it (thus reducing the undesired back-lobe and the reactive coupling to nearby circuits). These two properties are known to occur approximately over the frequency bandwidth where the phase of the reflection coefficient of the surface changes from +90 to 90. Since this behavior takes place at frequencies where the unit cell of the structure is small compared to the wavelength, it can be modeled in terms of a layered homogeneous material where each layer has an anisotropic magneto-dielectric tensor. These tensors, readily derived using an effective medium model, can be designed to obtain independent control of the bandwidths of gain increase and surface wave suppression. Based on a transverse resonance model of the effective medium material model, it is shown that Sievenpiper high-impedance surfaces exist that can suppress TE surface waves alone or TM surface waves alone, or both TE and TM surface waves at the same time. Maximum TM surface wave suppression bandwidth is obtained when the distance between the vias in the via array is as close as possible to 2. Maximum TE bandwidth is obtained when the conductors of the capacitive FSS offer maximum blockage to the normal magnetic field of the wave. A reduction of the transverse resonance solution to nearly closed form is used to obtain a simple picture of the design space available when the desired operating frequency is fixed.

Simple and Accurate Analytical Model of Planar Grids and High-Impedance Surfaces Comprising Metal Strips or Patches

“…In [29] the expressions for the input impedances of high-impedance surfaces have been derived by treating the capacitive grid layer and the metal-backed dielectric slab with embedded vias as homogeneous materials with an anisotropic magneto-dielectric tensor. The resulting expressions for the input impedances are lengthy and complicated compared to the expressions of the present paper.…”

The directivity of a compact antenna: an unforgettable figure of merit

“…The |S 11 | values as a function of the source frequency, and the 2D and 3D directivity patterns are shown in Figure 5. The resonance frequency is 301.14 MHz, giving ka = 0.474, where here "a = 75 mm", the ground plane radius, is also the radius of the smallest sphere enclosing the entire antenna.…”

“…These include, for example, end-fire arrays [5][6][7][8], electromagnetic band-gap (EBG) structures [9], high impedance surfaces and artificial magnetic conductors [10][11][12][13], nearfield resonant parasitic (NFRP) elements [14][15][16], nonFoster circuit-augmented antennas [17], two-element NFRP antenna arrays [18,19], and Huygens sources [20][21][22][23][24][25]. The metamaterial-inspired NFRP antenna designs have led to the realization of many performance enhancements of compact systems.…”

A Novel Bandpass Filter of Substrate Integrated Waveguide (Siw) Based on S-Shaped Ebg

“…The structure with this characteristic is called electromagnetic bandgap structures-EBG. Electromagnetic wave with some frequencies can not transmit, which seems like forming forbidden area [13][14][15][16].…”