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About this book

This book presents innovative ideas and technical contributions in the area of metasurfaces and antenna technologies. On the one hand, it presents an effective method to analyze metasurfaces constituted by metallic texture with certain geometries. It shows how this method can be applied to the design of metasurface (MTS) antennas for deep space communications and other planar microwave devices. On the other hand, the book reports on a general methodology developed for analyzing flat devices realized by using modulated MTSs, which opens new design possibilities for a large number of microwave devices based on the manipulation of SWs. Finally, a novel approach of reconfigurability, which is based on a class of checkerboard MTS, is explored. All in all, this book covers important insights and significant results on the emerging topic of metasurfaces, from theoretical and computational aspects to experiments.

Table of Contents


Chapter 1. Introduction

Metamaterials (MTMs) are artificial materials that are structured at a subwavelength scale to exhibit desired effective constitutive parameters. Achievable material parameters can include those not found in nature (Veselago, Sov Phys Usp 10(4):509, 1968, [1], Pendry, Phys Rev Lett 85:3966–3969, 2000, [2], Shelby et al., Science 292(5514):77–79, 2001, [3]). MTMs can be formed by periodic arrangements of many small inclusions in a dielectric host environment, so that the resulting effective medium possesses desired bulk properties.
Mario Junior Mencagli

Chapter 2. Surface Wave Dispersion for Anisotropic Metasurfaces Constituted by Elliptical Patches

As mentioned in the previous chapter, a simple anisotropic MTS can be obtained by periodically printing small elliptical patches on a grounded dielectric slab. Rotation of the ellipses with respect to the direction of SW propagation may provide control of the field polarization in circularly-polarized leaky-wave antennas or in TO SW-based devices.
Mario Junior Mencagli

Chapter 3. Closed-Form Representation of Metasurface Reactance and Isofrequency Dispersion Curve

The first part of this chapter proposes a formulation for the description of the equivalent reactance of MTS constituted by periodic small patches printed on a grounded dielectric slab. As already mentioned in the previous chapters, the printed elements are assimilated to homogenized scalar boundary conditions that can be represented by the circuit in Fig. 3.1. This scalar description is valid for printed elements with symmetric shapes (e.g. circular or square patches) and also for more complex elements with two axes of symmetry, provided the direction of propagation matches one of the symmetry axes of the printed elements (Fig. 3.1). A systematic way to extract a circuit description by a full-wave analysis is given by the pole-zero matching technique (Maci et al., IEEE Trans Antennas Propag 53(1):70–81, 2005, [1]), which requires the use of a Foster type expansion of the patch reactance. Derivation of a quasi-analytical representation of the circuit elements as a function of phasing is shown in the previous chapter for elliptical patches.
Mario Junior Mencagli

Chapter 4. Flat Optics for Surface Waves

As already mentioned in Chap. 1, a modulated MTS may be obtained by gradually varying the geometry of the elements in contiguous cells, while maintaining the period unchanged and electrically small. Macroscopically, this results in a modulation of the IBC that, due to the small dimensions of the unit cell, can be assumed to be almost continuous and locally treated by assuming each element as immersed in a periodic environment. The spatial variability of the IBC imposes a deformation of the SW wavefront, which addresses the local wavevector along non-rectilinear paths.
Mario Junior Mencagli

Chapter 5. Basic Properties of Checkerboard Metasurfaces

Checkerboard metasurface (CBMS) consists of an infinitesimally thin layer of electrically small complementary square metallic patches and apertures (Fig. 5.1). The name MTS is adopted here because the periodicity d of the checkerboard lattice is small in terms of the wavelength so that the global effect is the same as that of a continuous impedance surface. Propagation of waves driven by impedance discontinuity has been investigated in Quarfoth and Sievenpiper (IEEE Trans Antennas Propag 61(7):3597–3606, 2013, [1]). The present solution can be viewed as an implementation of this concept. In fact, the behavior of the CBMS changes depending on whether the square patches’ vertexes are connected by short-circuits or separated by a small gap.
Mario Junior Mencagli

Chapter 6. Conclusion

In this thesis we have theoretically and numerically examined the prospects of modulated metasurface (MTS) as a new platform for planar transformation optics devices, which allow one to manipulate the propagation of the supported surface waves (SWs). Such devices can be used as a part of flat lens antennas producing a fan-beam radiation pattern at microwaves, but can be also employed as components of optical circuits.
Mario Junior Mencagli


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