Metamaterial antenna - Knowledge (XXG)

1980:

parameters that are both inherently and simultaneously negative, obviating the need to employ separate means. The proposed media possess other desirable features including very wide bandwidth over which the refractive index remains negative, the ability to guide 2-D TM waves, scalability from RF to millimeter-wave frequencies and low transmission losses, as well as the potential for tunability by inserting varactors and/or switches in the unit cell. The concept has been verified with circuit and full-wave simulations. A prototype focusing device has been tested experimentally. The experimental results demonstrated focusing of an incident cylindrical wave within an octave bandwidth and over an electrically short area; suggestive of near-field focusing.

2337:). At certain frequencies ε < 0 and μ < 0 and n < 0. Like the DPS, the NIM has intrinsic impedance that is equal to the outside, and, therefore, is also lossless. The direction of power flow (i.e., the Poynting vector) in the first slab should be the same as that in the second one, because the power of the incident wave enters the first slab (without any reflection at the first interface), traverses the first slab, exits the second interface, enters the second slab and traverses it, and finally leaves the second slab. However, as stated earlier, the direction of power is anti-parallel to the direction of phase velocity. Therefore, the wave vector k 2055:. As a nonmagnetic conducting unit, it comprises an array of units that yield an enhanced negative effective magnetic permeability, when the frequency of the incident electromagnetic field is close to the SRR resonance frequency. The resonant frequency of the SRR depends on its shape and physical design. In addition, resonance can occur at wavelengths much larger than its size. For the further shape optimization of the elements it is expedient to use genetic and other optimization algorithms. In multi-frequency designs one may apply fractal designs such as those of Sierpensky, Koch or other fractals instead of SRRs. 1996:

equipped with lumped elements, which permit them to be compact at frequencies where the SRR cannot be compact. The flexibility gained through the use of either discrete or printed elements enables planar metamaterials to be scalable from the megahertz to the tens of gigahertz range. In addition, by utilizing varactors instead of capacitors, the effective material properties can be dynamically tuned. Furthermore, the proposed media are planar and inherently support two-dimensional (2-D) wave propagation. Therefore, these new metamaterials are well suited for RF/microwave device and circuit applications.

1859:

range. With this in mind, high pass and cutoff, periodically loaded, two-dimensional LC transmission line networks were proposed. The LC networks can be designed to support backward waves, without bulky SRR/wire structure. This was the first such proposal which veered away from bulk media for a negative refractive effect. A notable property of this type of network is that there is no reliance on resonance, Instead the ability to support backward waves defines negative refraction.

2492: 17: 1473: 1458: 424: 2152:. The operation frequency of the antenna was 3.52 GHz, which was determined by considering the geometrical parameters of SRR. An 8.32 mm length of wire was placed above the ground plane, connected to the antenna, which was one quarter of the operation wavelength. The antenna worked with a feed wavelength of 3.28 mm and feed frequency of 7.8 GHz. The SRR's resonant frequency was smaller than the monopole operation frequency. 1971:

E-plane pattern at 15 GHz showed radiation towards the backfire direction in the far-field pattern, clearly indicating the excitation of a backward wave. Since the transverse dimension of the array is electrically short, the structure is backed by a long metallic trough. The trough acts as a waveguide below cut-off and recovers the back radiation, resulting in unidirectional far-field patterns.

2611: 2184:. According to the numerical results, the antenna showed significant improvement in directivity, compared to conventional patch antennae. This was cited in 2007 for an efficient design of directive patch antennas in mobile communications using metamaterials. This design was based on the left-handed material (LHM) transmission line model, with the circuit elements L and C of the LHM 1274:, which then affects the relative permittivity and permeability of the overall microstrip line. It is introduced so that the wave impedance in the metamaterial remains unchanged. The index of refraction in the medium compensates for the dispersion effects associated with the microstrip geometry itself; making the effective refractive index of the pair that of free space. 1954:) was shown to exhibit NRI properties over a broad frequency range. This network will be referred to as a dual TL structure since it is of a high-pass configuration, as opposed to the low-pass representation of a conventional TL structure. Dual TL structures have been used to experimentally demonstrate backward-wave radiation and focusing at microwave frequencies. 2330:) is the same as that of the outside region and responding to a normally incident planar wave. The wave travels through the medium without any reflection because the DPS impedance and the outside impedance are equal. However, the plane wave at the end of DPS slab is out of phase with the plane wave at the beginning of the material. 3355: 2482:

A magnetic dipole was placed on metamaterial (slab) ground plane. The metamaterials have either constituent parameters that are both negative, or negative permittivity or negative permeability. The dispersion and radiation properties of leaky waves supported by these metamaterial slabs, respectively,

1873:

Electromagnetic waves from a point source located inside a conventional DPS can be focused inside an LHM using a planar interface of the two media. These conditions can be modeled by exciting a single node inside the DPS and observing the magnitude and phase of the voltages to ground at all points in

1748:

are often examined. Lumped circuit elements are actually microscopic elements that effectively approximate their larger component counterparts. For example, circuit capacitance and inductance can be created with split rings, which are on the scale of nanometers at optical frequencies. The distributed

2575:

The lens also functions as an input device and consists of a number of periodic unit-cells disposed along the line. The lens consists of multiple lines of the same make up; a plurality of periodic unit-cells. The periodic unit-cells are constructed of a plurality of electrical components; capacitors

2131:

parameters were R = 3.6 mm, r = 2.5 mm, w = 0.2 mm, t = 0.9 mm. R and r are used in annular parameters, w is the spacing between the rings and t = the width of the outer ring. The material had a thickness of 1.6 mm. Permittivity was 3.85 at 4 GHz. The SRR was fabricated

1991:

According to some researchers SRR/wire-configured metamaterials are bulky 3-D constructions that are difficult to adapt for RF/microwave device and circuit applications. These structures can achieve a negative index of refraction only within a narrow bandwidth. When applied to wireless devices at RF

1858:

loaded with capacitive and inductive elements in a high-pass configuration support certain types of backward waves. In addition, planar transmission lines are a natural match for 2-D wave propagation. With lumped circuit elements they retain a compact configuration and can still support the lower RF

1285:

Combining left-handed segments with a conventional (right-handed) transmission line results in advantages over conventional designs. Left-handed transmission lines are essentially a high-pass filter with phase advance. Conversely, right-handed transmission lines are a low-pass filter with phase lag.

379:

system could be produced. By stacking slabs of this configuration, the phase compensation (beam translation effects) would occur throughout the entire system. Furthermore, by changing the index of any of the DPS-DNG pairs, the speed at which the beam enters the front face, and exits the back face of

2417:

The phase compensator described above can be used to conceptualize the possibility of designing a compact 1-D cavity resonator. The above two-layer structure is applied as two perfect reflectors, or in other words, two perfect conducting plates. Conceptually, what is constrained in the resonator is

1885:

A transmission line that has lumped circuit elements that synthesize a left-handed medium is referred to as a "dual transmission line" as compared to "conventional transmission line". The dual transmission line structure can be implemented in practice by loading a host transmission line with lumped

2314:

The real component values for negative permittivity and permeability results in real component values for negative refraction n. In a lossless medium, all that would exist are real values. This concept can be used to map out phase compensation when a conventional lossless material, DPS, is matched

1970:

used one-dimensional LC loaded transmission line network, which supports fast backward-wave propagation to demonstrate characteristics analogous to "reversed Cherenkov radiation". Their proposed backward-wave radiating structure was inspired by negative refractive index LC materials. The simulated

2263:

At the interface between two media, the concept of the continuity of the tangential electric and magnetic field components can be applied. If either the permeability or permittivity of two media has opposite signs then the normal components of the tangential field, on both sides of the interface,

2034:

An antenna creates sufficiently strong electromagnetic fields at large distances. Reciprocally, it is sensitive to the electromagnetic fields impressed upon it externally. The actual coupling between a transmitting and receiving antenna is so small that amplifier circuits are required at both the

1881:

When transverse electromagnetic propagation occurs with a transmission line medium, the analogy for permittivity and permeability is ε = L, and μ = C. This analogy was developed with positive values for these parameters. The next logic step was realizing that negative values could be achieved. In

1250:

or microwave signals propagating along them would significantly decrease distortion. Therefore, components for attenuating distortion become less critical, and could lead to simplification of many systems. Metamaterials can eliminate dispersion along the microstrip by correcting for the frequency

2208:

This configuration uses a flat aperture constructed of zero-index metamaterial. This has advantages over ordinary (conventional) curved lenses, which results in a much improved directivity. These investigations have provided capabilities for the miniaturization of microwave source and non-source

2119:

and tunable operational frequency are produced with negative magnetic permeability. When combining a right-handed material (RHM) with a Veselago-left-handed material (LHM) other novel properties are obtained. A single negative material resonator, obtained with an SRR, can produce an electrically

2094:

The reactive power indicates that the DNG shell acts as a natural matching network for the dipole. The DNG material matches the intrinsic reactance of this antenna system to free space, hence the impedance of DNG material matches free space. It provides a natural matching circuit to the antenna.

1877:

Negative refraction and focusing can be accomplished without employing resonances or directly synthesizing the permittivity and permeability. In addition, this media can be practically fabricated by appropriately loading a host transmission line medium. Furthermore, the resulting planar topology

1995:

The proposed structures go beyond the wire/SRR composites in that they do not rely on SRRs to synthesize the material parameters, thus leading to dramatically increased operating bandwidths. Moreover, their unit cells are connected through a transmission-line network and they may, therefore, be

2155:

The monopole-SRR antenna operated efficiently at (λ/10) using the SRR-wire configuration. It demonstrated good coupling efficiency and sufficient radiation efficiency. Its operation was comparable to a conventional antenna at λ/2, which is a conventional antenna size for efficient coupling and

1999:

In the long-wavelength regime, the permittivity and permeability of conventional materials can be artificially synthesized using periodic LC networks arranged in a low-pass configuration. In the dual (high-pass) configuration, these equivalent material parameters assume simultaneously negative

1773:

limit, narrowband and broadband phase-shifting lines, small antennas, low-profile antennas, antenna feed networks, novel power architectures, and high-directivity couplers. Loading a planar metamaterial network of TLs with series capacitors and shunt inductors produces higher performance. This

2030:

is created in the elements by applying a voltage at the antenna terminals, causing the elements to radiate an electromagnetic field. In reception, the reverse occurs: an electromagnetic field from another source induces an alternating current in the elements and a corresponding voltage at the

1979:

Planar media can be implemented with an effective negative refractive index. The underlying concept is based on appropriately loading a printed network of transmission lines periodically with inductors and capacitors. This technique results in effective permittivity and permeability material

2259:

interact as a result of opposing permittivity and / or permeability values that are either ordinary (positive) or extraordinary (negative), notable anomalous behaviors may occur. The pair would be a DNG metamaterial (layer), paired with a DPS, ENG or MNG layer. Wave propagation behavior and

2042:

Dipole antennas, short antennas, parabolic and other reflector antennas, horn antennas, periscope antennas, helical antennas, spiral antennas, surface-wave and leaky wave antennas. Leaky wave antennas include dielectric and dielectric loaded antennas, and the variety of microstrip antennas.

2601:

This structure was designed for use in waveguiding or scattering of waves. It employs two adjacent layers. The first layer is an epsilon-negative (ENG) material or a mu-negative (MNG) material. The second layer is either a double-positive (DPS) material or a double-negative (DNG) material.

171:

This configuration analytically and numerically appears to produce an order of magnitude increase in power. At the same time, the reactance appears to offer a corresponding decrease. Furthermore, the DNG shell becomes a natural impedance matching network for this system.

78:

reflect most of the signal back to the source. A metamaterial antenna behaves as if it were much larger than its actual size, because its novel structure stores and re-radiates energy. Established lithography techniques can be used to print metamaterial elements on a

2264:

will be discontinuous at the boundary. This implies a concentrated resonant phenomenon at the interface. This appears to be similar to the current and voltage distributions at the junction between an inductor and capacitor, at the resonance of an L-C circuit. This "

2583:

The metamaterial incorporates a conducting transmission element, a substrate comprising at least a first ground plane for grounding the transmission element, a plurality of unit-cell circuits composed periodically along the transmission element and at least one

167:

The earliest research in metamaterial antennas was an analytical study of a miniature dipole antenna surrounded with a metamaterial. This material is known variously as a negative index metamaterial (NIM) or double negative metamaterial (DNG) among other names.

147:, thus making better use of available space for space-constrained cases. In these instances, miniature antennas with high gain are significantly relevant because the radiating elements are combined into large antenna arrays. Furthermore, metamaterials' negative 2592:

to at least the first ground plane. It also includes a means for suspending this transmission element a predetermined distance from the substrate in a way such that the transmission element is located at a second predetermined distance from the ground plane.

1957:

As a negative refractive index medium, a dual TL structure is not simply a phase compensator. It can enhance the amplitude of evanescent waves, as well as correct the phase of propagating waves. Evanescent waves actually grow within the dual TL structure.

2038:

The required antenna for any given application is dependent on the bandwidth employed, and range (power) requirements. In the microwave to millimeter-wave range – wavelengths from a few meters to millimeters – the following antennas are usually employed:

2444:. Therefore, in principle, one can have a thin subwavelength cavity resonator for a given frequency, if at this frequency the second layer acts a metamaterial with negative permittivity and permeability and the ratio correlates to the correct values. 1558:

From the simplified schematics to the right it can be seen that total impedance, conductance, reactance (capacitance and inductance) and the transmission medium (transmission line) can be represented by single components that give the overall value.

1346:

is just above zero. The relevant parameter is often the contrast between the permittivities rather than the overall permittivity value at desired frequencies. This occurs because the equivalent (effective) permittivity has a behavior governed by a

2366:, then the total phase difference between the front and back faces is zero. This demonstrates how the NIM slab at chosen frequencies acts as a phase compensator. It is important to note that this phase compensation process is only on the ratio of 2159:

When the SRR is made part of this configuration, characteristics such as the antenna's radiation pattern are entirely changed in comparison to a conventional monopole antenna. With modifications to the SRR structure the antenna size could reach

225:

Besides antenna miniaturization, the novel configurations have potential applications ranging from radio frequency devices to optical devices. Other combinations, for other devices in metamaterial antenna subsystems are being researched. Either

5208:

With the increasing proliferation of wireless devices inside and out of the home and workplace there are concerns over how interference from the external electromagnetic environment can cause problems for the connectivity of devices in the

2624:

Metamaterials can reduce interference across multiple devices with smaller and simpler shielding. While conventional absorbers can be three inches thick, metamaterials can be in the millimeter range—2 mm (0.078 in) thick.

2572:(MMIC), among other benefits. A transmission line is created with photolithography. A metamaterial lens, consisting of a thin wire array focuses the transmitted or received signals between the line and the emitter / receiver elements. 1289:

The conventional Leaky Wave antenna has had limited commercial success because it lacks complete backfire-to-endfire frequency scanning capability. The CRLH allowed complete backfire-to-endfire frequency scanning, including broadside.

216:

range by using both the forward and backward waves in leaky wave antennas. Various metamaterial antenna systems can be employed to support surveillance sensors, communication links, navigation systems and command and control systems.

1850:

In 2002, rather than using SRR-wire configuration, or other 3-D media, researchers looked at planar configurations that supported backward wave propagation, thus demonstrating negative refractive index and focusing as a consequence.

2564:

transmission lines by suspending them above the ground plane at a predetermined distance. In other words, they are not in contact with a solid substrate. Dielectric signal loss is reduced significantly, reducing signal attenuation.

2460:

LC circuitry configurations. Using FSS in a cavity allows for miniaturization, decrease of the resonant frequency, lowers the cut-off frequency and smooth transition from a fast-wave to a slow-wave in a waveguide configuration.

1941:

allowed the material properties to be dynamically tuned. The proposed media are planar and inherently support two-dimensional (2-D) wave propagation, making them well-suited for RF/microwave device and circuit applications.

1805:< 1), which restores the decaying evanescent waves from the source. This results in a diffraction-limited resolution of λ/6, after some small losses. This compares with λ/2, the normal diffraction limit for conventional 1882:

order to synthesize a left-handed medium (ε < 0 and μ < 0) the series reactance and shunt susceptibility should become negative, because the material parameters are directly proportional to these circuit quantities.

1789:, this allows for a more efficient coupling to external radiation and enables a broader frequency band. For example, the superlens can be applied to the TLM architecture. In conventional lenses, imaging is limited by the 1928:

elements, which permit them to be compact at frequencies where an SRR cannot be compact. The flexibility gained through the use of either discrete or printed elements enables planar metamaterials to be scalable from the

2276:

The geometry consists of two parallel plates as perfect conductors (PEC), an idealized structure, filled by two stacked planar slabs of homogeneous and isotropic materials with their respective constitutive parameters

2031:

antenna's terminals. Some receiving antennas (such as parabolic and horn types) incorporate shaped reflective surfaces to collect EM waves from free space and direct or focus them onto the actual conductive elements.

140:, with efficient power and acceptable bandwidth. Antennas employing metamaterials offer the possibility of overcoming restrictive efficiency-bandwidth limitations for conventionally constructed, miniature antennas. 333:

Although some SRR inefficiencies were identified, they continued to be employed as of 2009 for research. SRRs have been involved in wide-ranging metamaterial research, including research on metamaterial antennas.

5104:

Baccarelli, Paolo; Burghignoli, P.; Frezza, F.; Galli, A.; Lampariello, P.; Lovat, G.; Paulotto, S. (2005-01-17). "Effects of Leaky-Wave Propagation in Metamaterial Grounded Slabs Excited by a Dipole Source".

2405:

can be any value, as long as this ratio satisfies the above condition. Finally, even though this two-layer structure is present, the wave traversing this structure would not experience the phase difference.

2770:

Slyusar V. I. 60 Years of Electrically Small Antennas Theory.//Proceedings of the 6-th International Conference on Antenna Theory and Techniques, 17–21 September 2007, Sevastopol, Ukraine. - Pp. 116 - 118.

2301:. Choosing which combination of parameters to employ involves pairing DPS and DNG or ENG and MNG materials. As mentioned previously, this is one pair of oppositely-signed constitutive parameters, combined. 2447:

The cavity can conceptually be thin while still resonant, as long as the ratio of thicknesses is satisfied. This can, in principle, provide possibility for subwavelength, thin, compact cavity resonators.

1862:

The principles behind focusing are derived from Veselago and Pendry. Combining a conventional, flat, (planar) DPS slab, M-1, with a left-handed medium, M-2, a propagating electromagnetic wave with a

133:, for instance, an antenna would need to be half a meter long. In contrast, experimental metamaterial antennas are as small as one-fiftieth of a wavelength, and could have further decreases in size. 2537:

applications. In general phased array systems work by coherently reassembling signals over the entire array by using circuit elements to compensate for relative phase differences and time delays.

1410:= 0.1 eV. Perhaps the most important result of the interaction of metal and the plasma frequency is that permittivity is negative below the plasma frequency, all the way to the minute value of 2345:. Furthermore, whatever phase difference is developed by traversing the first slab can be decreased and even cancelled by traversing the second slab. If the ratio of the two thicknesses is 3771:

Ziolkowski, Richard W. and; Ching-Ying Cheng (2004-01-07). "Tailoring double negative metamaterial responses to achieve anomalous propagation effects along microstrip transmission lines".

372:

through the second slab the phase difference is significantly decreased and even compensated for. Therefore, as the wave exits the second slab the total phase difference is equal to zero.

1830:

A metamaterial-loaded transmission line has significant advantages over conventional or standard delay transmission lines. It is more compact in size, it can achieve positive or negative

4754: 1842:, leading to shorter group delays. It can work in lower frequency because of high series distributed-capacitors and has smaller plane dimensions than its equivalent coplanar structure. 4197: 981: 2079:

antennas can be notably increased. This could be accomplished by surrounding an antenna with a shell of double negative (DNG) material. When the electric dipole is embedded in a

1395:, independent of the wave vector of the EM excitation (radiation) field. Furthermore, a minute-fractionally small amount of plasmon energy is absorbed into the system denoted as 1866:

k1 in M-1, results in a refracted wave with a wave vector k2 in M-2. Since, M-2 supports backward wave propagation k2 is refracted to the opposite side of the normal, while the

3773: 3717: 2751: 954: 3035: 1870:

of M-2 is anti-parallel with k2. Under such conditions, power is refracted through an effectively negative angle, which implies an effectively negative index of refraction.

3305:

Slyusar V.I. Metamaterials on antenna solutions.// 7th International Conference on Antenna Theory and Techniques ICATT’09, Lviv, Ukraine, October 6–9, 2009. - Pp. 19 - 24

1886:

series capacitors (C) and shunt inductors (L). In this periodic structure, the loading is strong such that the lumped elements dominate the propagation characteristics.

1355:. Methods that have been developed theoretically using dielectric photonic crystals applied in the microwave domain to realize a directive emitter using metallic grids. 966: 5224:

Ziolkowski, R. W.; Lin, Chia-Ching; Nielsen, Jean A.; Tanielian, Minas H.; Holloway, Christopher L. (August–September 2009). "Design and Experimental Verification of".

4253: 4484:

Hsu, Yi-Jang; Huang, Yen-Chun; Lih, Jiann-Shing; Chern, Jyh-Long (2004). "Electromagnetic resonance in deformed split ring resonators of left-handed meta-materials".

1725: 349:

due to their negative index of refraction. This is accomplished by combining a slab of conventional lossless DPS material with a slab of lossless DNG metamaterial.

2192:

to determine the L and C values of the LHM equivalent circuit model for desirable characteristics of directive patch antennas. Design examples derived from actual

5226: 4038: 3043: 3011: 2553:

are reduced in size. This equates to a reduction in radiated energy loss, and a relatively wider useful bandwidth. The system is an efficient, dynamically ranged

21: 1535:

technology and is used to convey microwave-frequency signals. It consists of a conducting strip separated from a ground plane by a dielectric layer known as the

3384: 2853: 2240:

equipment. The desired affect is accomplished by varying the pattern of activated metamaterial elements as needed. The technology is a practical application of

1699: 1673: 1647: 1621: 1595: 1242:

of the signals' wave components, as they propagate in the DNG medium. Hence, stacked DNG metamaterials could be useful for modifying signal propagation along a

4776: 4691:

WU, Q.; Pan, P.; Meng, F.-Y.; Li, L.-W.; Wu, J. (2007-01-31). "A novel flat lens horn antenna designed based on zero refraction principle of metamaterials".

102: 2268:" is essentially independent of the total thickness of the paired layers, because it occurs along the discontinuity between two such conjugate materials. 3176:

Proceedings of the 3rd International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, London, UK, August 30th-September 4th, 2009

1898:, as with wireless devices, requires the resonators to be scaled to larger dimensions. This worked against making the devices more compact. In contrast, 1217: 986: 1819:

Metamaterials were first used for antenna technology around 2005. This type of antenna used the established capability of SNGs to couple with external

1277:

Part of the design strategy is that the effective permittivity and permeability of such a metamaterial should be negative – requiring a DNG material.

996: 2660: 1440:

are focused into a narrow cone. Dimensions are small in comparison to the wavelength and thus the slab behaves as a homogeneous material with a low

1266:

creating a dispersion-compensating segment of transmission line. This could be accomplished by introducing a metamaterial with a specific localized

4735: 2569: 1552: 4601:

Wang, Rui; Yuan, Bo; Wang, Gaofeng; Yi, Fan (2007). "Efficient Design of Directive Patch Antennas in Mobile Communications Using Metamaterials".

3910: 337:

A more recent view is that by using SRRs as building blocks, the electromagnetic response and associated flexibility is practical and desirable.

4762: 4358:"Experimental and theoretical verification of focusing in a large, periodically loaded transmission line negative refractive index metamaterial" 3587:"Experimental and theoretical verification of focusing in a large, periodically loaded transmission line negative refractive index metamaterial" 86:

These novel antennas aid applications such as portable interaction with satellites, wide angle beam steering, emergency communications devices,

5317: 821: 213: 4577: 4423: 4276: 3989: 3552: 3339: 3183: 2973: 2087:

without the interaction of the DNG material. In addition, the dipole-DNG shell combination increases the real power radiated by more than an

836: 458: 4228: 1983:

RF/microwave devices can be implemented based on these proposed media for applications in wireless communications, surveillance and radars.

2469:

As an LHM application four different cavities operating in the microwave regime were fabricated and experimentally observed and described.

1425: 3003: 2035:

transmitting and receiving stations. Antennas are usually created by modifying ordinary circuitry into transmission line configurations.

1812:

By combining right-handed (RHM) with left-handed materials (LHM) as a composite material (CRLH) construction, both a backward to forward

5279: 4815: 3171: 3646: 1391:

is a composite material. The effect of plasmons on any metal sample is to create properties in the metal such that it can behave as a

4949:"Guided Modes in a Waveguide Filled With a Pair of Single-Negative (SNG), Double-Negative (DNG), and/or Double-Positive (DPS) Layers" 1740:

Often, because of the goal that moves physical metamaterial inclusions (or cells) to smaller sizes, discussion and implementation of

716: 3117: 2091:

over a free space antenna. A notable decrease in the reactance of the dipole antenna corresponds to the increase in radiated power.

1493: 448: 3199: 1302:, found in metamaterial antenna systems, is used as an efficient coupler to external radiation, focusing radiation along or from a 1246:. At the same time, dispersion leads to distortion. However, if the dispersion could be compensated for along the microstrip line, 2156:

radiation. Therefore, the monopole-SRR antenna becomes an acceptable electrically small antenna at the SRR's resonance frequency.

3172:"Metamaterial-inspired electrically small radiators: it is time to draw preliminary conclusions and depict the future challenges" 4030: 631: 3820: 4290: 1210: 976: 453: 193: 59:

into free space. However, this class of antenna incorporates metamaterials, which are materials engineered with novel, often

1874:

the LHM. A focusing effect should manifest itself as a “spot” distribution of voltage at a predictable location in the LHM.

4144: 1765:

Some noted metamaterial antennas employ negative-refractive-index transmission-line metamaterials (NRI-TLM). These include

4800: 1992:

frequencies the split ring-resonators have to be scaled to larger dimensions, which, in turn forces a larger device size.

1775: 991: 696: 5192: 2665: 2640: 2064: 856: 846: 831: 596: 463: 227: 4645: 896: 586: 5001: 4948: 4888: 4836: 3837: 3712: 3143: 2577: 1501: 1149: 1024: 921: 4413: 3238: 3212: 1374:. The lattice constant or lattice parameter refers to the constant distance between unit cells in a crystal lattice. 816: 4784: 2015: 649: 48: 4889:"An Idea for Thin Subwavelength Cavity Resonators Using Metamaterials With Negative Permittivity and Permeability" 3392: 2545:

Patented in 2004, one phased array antenna system is useful in automotive radar applications. By using NIMs as a

2533:

Phased array systems and antennas for use in such systems are well known in areas such as telecommunications and

1910: 1750: 1745: 1203: 1164: 691: 681: 621: 616: 556: 310:

In 2002, a different class of negative refractive index (NRI) metamaterials was introduced that employs periodic

152: 3448:

Shelby, R. A.; Smith, D. R.; Schultz, S. (2001). "Experimental Verification of a Negative Index of Refraction".

2791: 2602:

Alternatively, the second layer can be an ENG material when the first layer is an MNG material or the reverse.

1827:

allowed for a wavelength larger than the antenna. At microwave frequencies this allowed for a smaller antenna.

1567: 1134: 1014: 701: 2232:

and motors are replaced by arrays of metamaterials in a planar configuration. Also, with this new technology

3654: 3525: 2848: 2670: 1139: 1109: 541: 531: 526: 357: 246:, waveguides, scatters and antennas (radiators). Metamaterial antennas were commercially available by 2009. 1351:

in the microwave domain. This low optical index material then is a good candidate for extremely convergent

5322: 5243: 5175:; Alù, Andrea "Waveguides and scattering devices incorporating epsilon-negative and/or mu-negative slabs" 4456: 4315: 4010: 3873: 3465: 3261: 2746: 2675: 2635: 2019: 1650: 961: 731: 506: 129:. Standard antennas need to be at least half the size of the signal wavelength to operate efficiently. At 98: 5285: 4091: 1878:

permits LHM structures to be readily integrated with conventional planar microwave circuits and devices.

1574:

as closely as possible, because it is usually desirable that the load absorbs as much power as possible.

330:

interfaced with a positive index, parallel-plate waveguide. This was experimentally verified soon after.

3239:"Application of Double Negative Materials to Increase the Power Radiated by Electrically Small Antennas" 3031: 2710: 2705: 2690: 2685: 2655: 2241: 2197: 2124: 2080: 1918: 1598: 1532: 1437: 1271: 1059: 746: 736: 686: 676: 423: 273: 201: 80: 1417:

These facts ultimately result in the arrayed wire structure as being effectively a homogeneous medium.

5291: 3950: 1924:

Moreover, their unit cells are connected through a transmission-line network and may be equipped with

5235: 5114: 5060: 5013: 4960: 4900: 4848: 4700: 4657: 4610: 4532: 4493: 4448: 4369: 4330: 4212: 4159: 4106: 3926: 3782: 3726: 3663: 3603: 3457: 3253: 3052: 2917: 2862: 2807: 2695: 2615: 2104: 2023: 1754: 1741: 1497: 1462: 1421: 1184: 1084: 1049: 801: 666: 566: 551: 486: 311: 292: 288: 242:

slabs are employed in the subsystems. Antenna subsystems that are currently being researched include

5248: 4461: 4092:"Experimental verification of backward-wave radiation from a negative refractive index metamaterial" 3470: 3356:"NETGEAR Ships 'The Ultimate Networking Machine' for Gamers, Media Enthusiasts and Small Businesses" 3266: 2491: 1806: 591: 4519:

Aydin, Koray; Bulu, Irfan; Guven, Kaan; Kafesaki, Maria; Soukoulis, Costas M; Ozbay, Ekmel (2005).

2902: 2715: 2589: 2027: 1544: 1489: 1485: 1263: 1231: 1144: 1124: 1119: 926: 911: 796: 766: 661: 353: 323: 319: 64: 4560:

Fangming Zhu; Qingchun Lin; Jun Hu (2005). "A Directive Patch Antenna with a Metamaterial Cover".

2247:

Research and applications of metamaterial based antennas. Related components are also researched.

272:"), and that a periodic array of copper split ring resonators could produce an effective negative 5261: 5130: 5029: 4976: 4916: 4837:"Pairing an epsilon-negative slab with a mu-negative slab: Resonance, tunneling and transparency" 4716: 4673: 4626: 4583: 4282: 4055: 3798: 3742: 3558: 3491: 3068: 2943: 2720: 2554: 2256: 2185: 2177: 2112: 2088: 1906: 1794: 1540: 1019: 759: 561: 521: 4521:"Investigation of magnetic resonances for different split-ring resonator parameters and designs" 4439:

Pendry, J.B.; et al. (1999). "Magnetism from conductors and enhanced nonlinear phenomena".

2326:

has ε < 0 and μ < 0. Assume that the intrinsic impedance of the DPS dielectric material (d

387:

Furthermore, this phase compensation can lead to a set of applications, which are miniaturized,

364:

is radiated on this configuration. As this wave propagates through the first slab of material a

16: 3529: 3414: 3210:

Proceedings of the Virtual Institute for Artificial Electromagnetic Materials and Metamaterials

3015: 1428:

of an electromagnetic radiation source located inside the material in order to collect all the

5086: 4573: 4419: 4387: 4272: 3985: 3975: 3942: 3647:"Hybrid metamaterials enable fast electrical modulation of freely propagating terahertz waves" 3621: 3548: 3483: 3335: 3179: 2823: 2585: 2220:(M-SAT) is an invention that uses metamaterials to direct and maintain a consistent broadband 1855: 1790: 1786: 1728: 1548: 1481: 1465: 1382: 1299: 1235: 1079: 396: 381: 315: 137: 2260:

properties may occur that would otherwise not happen if only DNG layers are paired together.

1710: 5253: 5122: 5078: 5068: 5021: 4968: 4908: 4856: 4812: 4708: 4665: 4618: 4565: 4540: 4501: 4466: 4377: 4338: 4264: 4220: 4167: 4114: 4047: 3981: 3934: 3918: 3790: 3734: 3671: 3611: 3540: 3475: 3271: 3189: 3060: 2982: 2933: 2925: 2870: 2815: 2799: 2680: 2141: 2072: 1798: 1441: 1371: 1348: 1343: 1339: 1331: 1311: 1179: 1094: 1054: 1044: 931: 886: 869: 786: 721: 491: 415: 392: 369: 296: 148: 1472: 1457: 4819: 3824: 3679: 3586: 3216: 3203: 2221: 2108: 2068: 2009: 1895: 1867: 1363: 1359: 1306:

transmission line into transmitting and receiving components. Hence, it can be used as an

1247: 1114: 1039: 1034: 901: 776: 741: 636: 601: 501: 205: 185: 144: 125:

of an antenna. The newest metamaterial antennas radiate as much as 95 percent of an input

122: 68: 52: 40: 4316:"Planar negative refractive index media using periodically L-C loaded transmission lines" 4145:"Planar Negative Refractive Index Media Using Periodically L–C Loaded Transmission Lines" 3331: 3124: 1154: 5292:

Microwave transmission-line networks for backward-wave media and reduction of scattering

5239: 5118: 5064: 5017: 4964: 4904: 4852: 4704: 4661: 4614: 4536: 4497: 4452: 4373: 4334: 4216: 4163: 4110: 3930: 3786: 3730: 3667: 3607: 3461: 3257: 3196: 3118:"Analysis and Design of a Cylindrical EBG based directive antenna, Halim Boutayeb et al" 3056: 2921: 2866: 2811: 5301: 3594: 2546: 1925: 1835: 1702: 1684: 1658: 1632: 1606: 1580: 1433: 1074: 1069: 891: 781: 706: 656: 606: 579: 536: 511: 481: 474: 4261:

IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313)

5311: 5172: 4944: 4940: 4720: 4630: 4286: 4063: 3708: 3425: 2233: 2173: 2145: 1766: 1517: 1509: 1234:

as a transmission medium, it could be useful as a dispersion compensation device for

1189: 1174: 1159: 1099: 811: 726: 711: 626: 611: 516: 388: 365: 346: 44: 5134: 5033: 4920: 4587: 4545: 4520: 4059: 3802: 3746: 3562: 3306: 2051:

The SRR was introduced by Pendry in 1999, and is one of the most common elements of

380:

the entire stack-system changes. In this manner, a volumetric, low loss, time delay

208:

efficiency and axial ratio performance of low-profile antennas located close to the

5265: 5159: 4677: 3838:"Emerging Metamaterials Antennas and their advantages over conventional approaches" 3816: 3495: 3072: 2947: 2650: 2237: 2052: 1914: 1899: 1367: 1307: 1267: 1255: 1169: 1064: 1029: 971: 906: 791: 671: 546: 265: 239: 235: 231: 209: 197: 181: 126: 29: 5304:

Manual of Regulations and Procedures for Federal Radio Frequency Management. 2011.

4980: 2819: 2083:

DNG medium, the antenna acts inductively rather than capacitively, as it would in

1286:

This configuration is designated composite right/left-handed (CRLH) metamaterial.

826: 3325: 2851:(2003-10-14). "Periodically LTL With Effective NRI and Negative Group Velocity". 1834:

while occupying the same short physical length and it exhibits a linear, flatter

67:. Antenna designs incorporating metamaterials can step-up the antenna's radiated 5286:

The electrodynamics of substances with simultaneously negative values of ε and μ

4777:"Kymeta spins out from Intellectual Ventures after closing $ 12 million funding" 3938: 3906: 3034:; Jin, Peng; Nielsen, J. A.; Tanielian, M. H.; Holloway, Christopher L. (2009). 2610: 2209:

devices, circuits, antennas and the improvement of electromagnetic performance.

2181: 2128: 2116: 1863: 1831: 1770: 1676: 1239: 1089: 941: 771: 433: 376: 326:(DPS) material with negative index material (DNG). It employed a small, planar, 60: 4813:

AFRL-Demonstrated Metamaterials Technology Transforms Antenna Radiation Pattern

4198:"Growing evanescent waves in negative-refractive-index transmission-line media" 3544: 32:, greatly boosting the radiated signal. The square is 30 millimeters on a side. 5257: 5177: 4789:

Company to commercialize IV's metamaterials-based satellite antenna technology

4712: 4622: 4569: 3064: 2772: 2561: 2495: 2164:). Coupling 2, 3, and 4 SRRs side by side slightly shifts radiation patterns. 2084: 1624: 1528: 1521: 1392: 1303: 1259: 1243: 806: 361: 75: 25: 5126: 5025: 4972: 4912: 4342: 4268: 4171: 4051: 3794: 3738: 3092: 2000:

values, and may therefore be used to synthesize a negative refractive index.

1946:

Growing evanescent waves in negative-refractive-index transmission-line media

1476:

Schematic representation of the elementary components of a transmission line.

1258:-loaded transmission line that can be introduced with the original length of 360:-matched to the outside region (e.g., free space). The desired monochromatic 264:

array of intersecting, thin wires could be used to create negative values of

4860: 4669: 3537:

2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278)

3479: 3275: 2967:

Wu, B.-I.; W. Wang; J. Pacheco; X. Chen; T. Grzegorczyk; J. A. Kong (2005).

2874: 2700: 2518:) spiral inductor delay lines to 401. 404 are also connected to ground vias 2225: 2193: 2149: 1934: 1930: 1839: 1820: 1782: 1513: 1352: 1129: 1104: 916: 841: 438: 327: 304: 300: 261: 243: 189: 156: 130: 110: 5090: 4646:"Subwavelength, Compact, Resonant Patch Antennas Loaded With Metamaterials" 4391: 3946: 3877: 3848: 3625: 3487: 3147: 3135: 2929: 2827: 2790:

Enoch, Stefan; Tayeb, G; Sabouroux, P; Guérin, N; Vincent, P (2002-11-04).

5282:

Demonstrated metamaterials technology transforms antenna radiation pattern

3847:. Electromagnetic Theory Symposium 2007 (EMTS 2007): 01–03. Archived from 3209: 3027:

Some content is derived from Public Domain material on the NIST web site.

1562:

With transmission line media it is important to match the load impedance Z

5073: 5049:"Experimental observation of cavity formation in composite metamaterials" 5048: 4382: 4357: 4254:"A backward-wave antenna based on negative refractive index L-C networks" 3616: 2987: 2968: 2550: 2506:

represents unit-cell circuits composed periodically along the microstrip.

1938: 1824: 881: 876: 496: 2255:

When the interface between a pair of materials that function as optical

2115:

over a comparable free space antenna. Electrically small antennas, high

24:

is smaller than a standard antenna with comparable properties. Its high

5082: 4031:"Characteristics of the Composite Right/Left-Handed Transmission Lines" 2938: 2903:"Radiation properties of a split ring resonator and monopole composite" 2618: 2189: 2148:, ground plane and radiating components. The ground plane material was 1378: 851: 5296: 5154: 5152: 5150: 5148: 5146: 5144: 4644:

Alu, Andrea; Bilotti, Filiberto; Engheta, Nader; Vegni, Lucio (2007).

4505: 4470: 4224: 4118: 3675: 2969:"A Study of Using Metamaterials as Antenna Substrate to Enhance Gain" 2645: 2527: 2409:

Following this, the next step is the subwavelength cavity resonator.

2229: 2137: 2076: 1902:

configurations could be scaled to both microwave and RF frequencies.

1429: 936: 443: 254: 121:

Antenna designs incorporating metamaterials can step-up the radiated

87: 56: 4143:

Eleftheriades, George V.; Iyer, A.K.; Kremer, P.C. (December 2002).

3585:

Iyer, Ashwin K.; Kremer, Peter; Eleftheriades, George (2003-04-07).

2244:

theory. The antenna is approximately the size of a laptop computer.

4755:"Intellectual Ventures Invents Beam-Steering Metamaterials Antenna" 3436:

LG Chocolate BL40 is first cellphone to use a metamaterials antenna

2200:

were performed, which illustrates the efficiency of this approach.

2127:

rings with relative opposite gaps in the inner and outer ring. Its

2120:

small antenna when operating at microwave frequencies, as follows:

55:. Their purpose, as with any electromagnetic antenna, is to launch 2609: 2534: 2133: 1813: 1471: 1456: 1323: 91: 15: 143:

Metamaterials permit smaller antenna elements that cover a wider

28:

is derived from the "Z element" inside the square that acts as a

1505: 1335: 1327: 356:, while the DNG has a negative refractive index. Both slabs are 2413:

Compact subwavelength 1-D cavity resonators using metamaterials

5047:

Caglayan, Humeyra; Bulu, I; Loncar, M; Ozbay, E (2008-07-21).

4736:"Bill Gates Invests In Intellectual Ventures' Spin-Out Kymeta" 3530:"Negative refractive index metamaterials supporting 2-D waves" 3359:(...eight ultra-sensitive, internal, metamaterial antennas...) 2456:

Frequency selective surface (FSS) based metamaterials utilize

106: 3911:"Extremely Low Frequency Plasmons in Metallic Mesostructures" 2322:

has ε > 0 and μ > 0. Conversely, the NIM of thickness d

4314:

Eleftheriades, G.V.; Iyer, A.K.; Kremer, P.C. (2002-12-16).

3036:"Experimental Verification of Z Antennas at UHF Frequencies" 1921:

resulted in a substantial increase in operating bandwidths.

1846:

Negative refractive index metamaterials supporting 2-D waves

1531:

is a type of transmission line that can be fabricated using

3580: 3578: 3004:"Engineered Metamaterials Enable Remarkably Small Antennas" 1962:

Backward wave antenna using an NRI loaded transmission line

4407: 4405: 4403: 4401: 2022:. Physically, an antenna is an arrangement of one or more 74:

Conventional antennas that are very small compared to the

4356:

Iyer, Ashwin; Peter Kremer; George Eleftheriades (2003).

3519: 3517: 3515: 3513: 3511: 3509: 3507: 3505: 3237:

Ziolkowski, Richard Wly; Allison D. Kipple (2003-10-14).

2568:

This system was designed to boost the performance of the

368:

emerges between the exit and entrance faces. As the wave

136:

Metamaterials are a basis for further miniaturization of

5193:"Metamaterials to revolutionize wireless infrastructure" 2123:

The configuration of an SRR assessed was two concentric

1749:

LC model is related to the lumped LC model, however the

1342:

can be positive and less than one. This means that the

5002:"A Metamaterial Surface for Compact Cavity Resonators" 4603:

International Journal of Infrared and Millimeter Waves

4252:

Grbic, Anthony; George V. Eleftheriades (2002-08-07).

4196:

Grbic, Anthony; George V. Eleftheriades (2003-03-24).

4090:

Grbic, Anthony; George V. Eleftheriades (2002-11-15).

3319: 3317: 3315: 3313: 2896: 2894: 2892: 2890: 2888: 2886: 2884: 2560:

In addition, signal amplitude is increased across the

184:

surrounding antennas offer improved isolation between

3713:"A Positive Future for Double-Negative Metamaterials" 2478:

Leaky mode propagation with metamaterial ground plane

1713: 1687: 1661: 1635: 1609: 1583: 1314:, as well as correct the phase of propagating waves. 291:(SRR), with thin wire conducting posts and produce a 5107: