Magneto-Electric Dipole Antenna Arrays

A planar magneto-electric (ME) dipole antenna array is proposed and demonstrated by both full-wave analysis and experiments. The proposed structure leverages the infinite wavelength propagation characteristic of composite right/left-handed (CRLH) transmission lines to form high-gain magnetic radiators combined with radial conventional electric radiators, where the overall structure is excited by a single differential feed. The traveling-wave type nature of the proposed ME-dipole antenna enables the formation of directive arrays with high-gain characteristics and scanning capability. Peak gains of 10.84 dB and 5.73 dB are demonstrated for the electric dipole and magnetic-dipole radiation components, respectively.Comment: 9 pages, 17 figure

Tomorrow's Metamaterials: Manipulation of Electromagnetic Waves in Space, Time and Spacetime

Metamaterials represent one of the most vibrant fields of modern science and technology. They are generally dispersive structures in the direct and reciprocal space and time domains. Upon this consideration, I overview here a number of metamaterial innovations developed by colleagues and myself in the holistic framework of space and time dispersion engineering. Moreover, I provide some thoughts regarding the future perspectives of the area

Application of Composite Right/Left-Handed Metamaterials in Leaky-Wave Antennas

This chapter reviews the most significant advancements in the context of metamaterial (MTM) leaky wave antennas (LWAs). A brief review of the mechanism of leaky wave radiation along with an important class of MTMs known as composite right/left-handed (CRLH) structures is presented. Then, recent outstanding works in the area of CRLH LWAs are reported in detail. These works include the application of electronic control, substrate integrated waveguides, dual band and wideband performance, ferrite loaded waveguides, and split-ring-resonator (SRR)-based MTMs in LWAs. Also, the benefits of LWAs to design high gain active structures, reflecto-directive systems, wideband dual-layer substrate integrated waveguide antennas and conformal antennas are discussed

Synthesis and design of novel metamaterial radiation structures

The present thesis deals with the design and practical implementation of novel netamaterial planar antenna structures based on Complementary Split Ring Resonator (CSRR) particles. As CSRR particles display a very attractive electrical performance when used as unit cell for metasurfaces, the authors of this thesis have proposed to implement such particles in waveguide lters. In this case, the possibility to design waveguide lters with lengths equal to the thickness of a metallic sheet is con rmed. Consequently, the proposed structure constitutes a signi cant reduction of the dimensions of the well-known resonant cavity waveguide lters coupled by irises. The behavior of CSRR particles within compact waveguide lter suggested the authors to use them as stand alone radiating elements. As expected, due to the reduced electrical volume of CSRRs, such particles exhibited low radiation e ciency. In order to improve the radiation e ciency, the idea to implement CSRRs inside a larger structure came to us. Measurement results con rm this hypothesis and raise the question to design multi-band antennas. In order to implement multi-band antennas, several CSRRs are inserted at di erent positions in the patch. It is then observed that the grouping of CSRRs can provide either multi-band operation or polarization rotation capabilities, when Electro-Inductive Waves (EIW) are supported. Finally, thanks to EIW propagation, the idea to use longer CSRR chains as radiating structures came to us. As an intermediate step, and in order to validate simulated results, a nite array composed of nine CSRRs is manufactured and partially tested. Though partial, this test results are very encouraging and motivate a more in deep measurement campaign. This campaign is expected to result into new publications on this topic. These results support the use of the proposed CSRR chains for the design of leaky wave antennas.Programa Oficial de Doctorado en Tecnologías de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007

Low-Profile Metamaterial-Based Adaptative Beamforming Techniques

In this chapter, we will review recent research advances on beamforming and spatial multiplexing techniques using reconfigurable metamaterials (MTMs) and metasurfaces. This chapter starts by discussing basic principles and practical applications of transmission line-based metamaterials and planar metasurfaces, followed by their active versions that enable novel smart antennas with beam steering and beamshaping functions. We include detailed descriptions of their practical realizations and the integration with circuits and the radio-frequency (RF) frontend, which are used to adaptively and dynamically manipulate electromagnetic radiation. We summarize the state-of-the-art MTM/metasurface-based beamforming techniques and provide a critical comparison for their uses in the RF-to-millimeter-wave range in terms of cost, reconfigurability, system integratability and radiation properties. These techniques are expected to pave the way for the massive deployment of communication, radar, remote sensing and medical and security imaging systems

Antennas using left handed transmission lines

The research described in this thesis is concerned with the analysis and design of conventional wire antenna types, dipoles and loops, based on the left-handed transmission line approach. The left handed antennas have a unique feature that the wavelength of the induced current becomes shorter with decreasing frequency. The left handed transmission line concept can be extended to construct reduced-size dipole or loop antennas in the VHF frequency band. The use of higher order modes allows orthogonal polarisation to be obtained, which is thought to be a feature unique to these antennas. Efficiency is a key parameter of left handed antennas as the heavy left handed loading increases the resistive loss. A study of the efficiency of small dipole antennas loaded with a left-handed transmission line is specially described, and the comparison with conventional inductive loading dipoles. In a low order mode, the efficiency of L-loading dipole is better with low number of unit cell. If the number of cell increases, CL-loading presents comparable and even better performance. In a high mode the meandered left handed dipole gives the best efficiency due to the phase distribution, presenting orthogonal polarization as well. The optimized dipole loaded with parallel plate capacitors and spiral inductors presents the best performance in impedance and efficiency, even better than the conventional inductive loading. A planar loop antenna using a ladder network of left handed loading is also presented. Various modes can be obtained in the left handed loop antenna. The zero order mode gives rise to omnidirectional patterns in the plane of the loop, with good efficiency. By loading the loop with active components, varactors, a tunable left handed loop antenna with a switchable radiation pattern is implemented. The loop gives an omnidirectional pattern with a null to z axis while working in an n = 0 mode and can switch to a pattern with a null at phi = 45° in the plane of the loop in an n = 2 mode

A Review: Substrate Integrated Waveguide Antennas and Arrays

This study aims to provide an overview and deployment of Substrate-Integrated Waveguide (SIW) based antenna and arrays, with different configurations, feeding mechanisms, and performances. Their performance improvement methods, including bandwidth enhancement, size reduction, and gain improvement are also discussed based on available literature. SIW technology, which acts as a bridge between planar and non-planar technology, is a very favorable candidate for the development of components operating at microwave and millimeter wave band. Due to this, SIW antennas and array take the advantages of both classical metallic waveguide, which includes high gain, high power capacity, low cross polarization, and high selectivity, and that of planar antennas which comprises low profile, light weight, low fabrication cost, conformability to planar or bent surfaces, and easy integration with planar circuits

State-of-the-Art of Metamaterials: Characterization, Realization and Applications

Metamaterials is a large family of microwave structures that produces interesting ε and μ conditions with huge implications for numerous electromagnetic applications. Following a description of modern techniques to realize epsilon-negative, mu-negative and double-negative metamaterials, this paper explores recent literature on the use of metamaterials in hot research areas such as metamaterial-inspired microwave components, antenna applications and imaging. This contribution is meant to provide an updated overview of complex microwave engineering for the generation of different types of metamaterials and their application in topical electromagnetic scenarios

A Wide Frequency Scanning Printed Bruce Array Antenna with Bowtie and Semi-Circular Elements

A printed edge-fed counterpart of the wire Bruce array antenna, for frequency scanning applications, is presented in this paper. The unit-cell of the proposed antenna consists of bowtie and semi-circular elements to achieve wide bandwidth from below 22 GHz to above 38 GHz with open-stopband suppression. The open-stopband suppression enables a wide seamless scanning range from backward, through broadside, to forward endfire. A sidelobe threshold level of −10 dB is maintained to evaluate efficient scanning performance of the antenna. The antenna peak realized gain is 15.30 dBi, and, due to its compact size, has the ability to scan from −64° to 7