Metamaterials are a new class of ordered composites that exhibit unusual electromagnetic properties that are not readily observed in nature. These artificial materials with their simultaneously negative permittivity and permeability properties have attracted widespread interest in recent years. They are constructed from an array of metallic material in dielectric and magnetic substrates and exhibit unusual electromagnetic properties. Recent research into metamaterials has not only demonstrated interesting physical phenomena but has also lead to the development of design procedures and the realization of promising new types of microwave, millimeter-wave and optical components and devices. New-type metamaterials would open up a new field of automotive electronics applications, such as beam-scanned antenna systems for radar and mobile communications, novel magnetic materials for electric motors and the high-performance absorbing and shielding materials need for electromagnetic compatibility, and optical devices such as LED headlights and night vision systems using infrared cameras. In this review, we present a survey of metamaterials and present an overview of our recent R&D activities related to metamaterial design and their application to mobile antennas.

This paper describes a topology optimization method that has been designed for application to the structures of electromagnetic materials. The goal of topology optimization is to produce high-performance structures. As such, it has been extensively applied to a variety of structural optimization problems. Also, its application to the task of electromagnetic material structure design has the potential to be extremely useful. In this article, we introduce two topology optimization methods for the structural design of electromagnetic materials. One is based on the periodic boundary Finite Element Method (FEM) that is used to design periodic material structures. The second method is based on time domain analysis using the Finite Difference-Time Domain (FDTD) method where we can directly deal with the frequency characteristics that are formulated as an integral through a continuous frequency range suitable for RF device design. Several design examples are presented in order to confirm the usefulness of the proposed method.

Hideo Iizuka, Peter S. Hall

A new concept to form a dipole antenna using a left-handed transmission line is proposed. The antenna is composed of a ladder network periodic structure of unit cells having series capacitors and shunt inductors. Placing capacitors into one side of the network leads to out of phase currents with different amplitudes that allow strong radiation. The antenna has a unique feature of reduced wavelength with decreasing frequency. The concept is applied for three antennas. The first one is a small dipole, whilst working in an n = -1 mode, based on conventional resonance numbering. The dipole with a length of 0.18 wavelengths can have an input impedance of 50Ω. The second one is an orthogonally polarised dipole. A left-handed meandered dipole using higher order mode gives a polarisation orthogonal to that of a conventional right-handed one. The third one is an omnidirectional loop. The loop has a one wavelength circumference and gives an omnidirectional pattern in the plane of the loop, whilst using the zeroth mode. In contrast, a conventional right-handed loop has a figure of eight pattern. It is confirmed by the numerical analysis that the proposed concept significantly extends the design degrees of freedom for wire antennas.