Metal-Lens Antennas
01 Nov 1946-Vol. 34, Iss: 11, pp 828-836
TL;DR: In this article, a new type of antenna is described which utilizes the optical properties of radio waves, which consists of a number of conducting plates of proper shape and spacing and is, in effect, a lens, the focusing action of which is due to the high phase velocity of a wave passing between the plates.
Abstract: A new type of antenna is described which utilizes the optical properties of radio waves. It consists of a number of conducting plates of proper shape and spacing and is, in effect, a lens, the focusing action of which is due to the high phase velocity of a wave passing between the plates. Its field of usefulness extends from the very short waves up to wavelengths of perhaps five meters or more. The paper discusses the properties of this antenna, methods of construction, and applications.
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TL;DR: In this article, the basic physics and applications of planar metamaterials, often called metasurfaces, which are composed of optically thin and densely packed planar arrays of resonant or nearly resonant subwavelength elements, are reviewed.
1,047 citations
TL;DR: It is pointed out that the boundary between “ordinary” materials and metamaterials is difficult to draw because also many everyday natural materials are dielectric mixtures which may display very surprising and non-linear macroscopic response functions.
443 citations
TL;DR: In this article, the authors proposed and demonstrated metamaterial-based strain sensors that are highly sensitive to mechanical deformation and their resonance frequency shift is correlated with the surface strain of the test material and the strain data are reported telemetrically.
Abstract: We proposed and demonstrated metamaterial-based strain sensors that are highly sensitive to mechanical deformation. Their resonance frequency shift is correlated with the surface strain of our test material and the strain data are reported telemetrically. These metamaterial sensors are better than traditional radio-frequency (rf) structures in sensing for providing resonances with high quality factors and large transmission dips. Using split ring resonators (SRRs), we achieve lower resonance frequencies per unit area compared to other rf structures, allowing for bioimplant sensing in soft tissue (e.g., fracture healing). In 5×5 SRR architecture, our wireless sensors yield high sensitivity (109 kHz/kgf, or 5.148 kHz/microstrain) with low nonlinearity error (<200 microstrain).
178 citations
TL;DR: In this article, a three-dimensional broadband, low-loss, dual-polarization, and high-directivity lens antenna using gradient index (GRIN) metamaterials, which is composed of multi-layer microstrip square-ring arrays.
Abstract: We present the theoretical modeling and prototype demonstration of a three-dimensional broadband, low-loss, dual-polarization, and high-directivity lens antenna using gradient index (GRIN) metamaterials, which is composed of multi-layer microstrip square-ring arrays. The elements of metamaterials, closed square-ring units of variable sizes, are distributed on the planar substrate to satisfy the radial gradient index function and the axial impedance matching layer configuration of the lens. The gradient-index metamaterials are designed to transform the spherical wave-front into the planar wave-front and to minimize the reflection loss. A prototype lens antenna, which consists of a metal conical horn and the gradient-index lens, are simulated, constructed, and measured. The resemblance of simulation and measurement results shows that the prototype lens antenna maintains low return loss and high directivity on the whole X-band (from 8 GHz to 12 GHz). Compared to the traditional horn antenna, the metamaterial...
174 citations
01 Oct 1953
TL;DR: In this article, two types of artificial dielectric are examined; the first consists of an array of conducting rods and the second of a set of parallel conducting plates having perforations in the form of circular holes.
Abstract: Two types of artificial dielectric are examined; the first consists of an array of conducting rods and the second of a set of parallel conducting plates having perforations in the form of circular holes. Both these media are designed to operate for an incident electromagnetic wave, which is polarized so that its electric field is parallel to the conducting elements. It is found that the effective refractive index of such media is less than unity. An analysis of the propagation within these media gives results from which the effective refractive index may be calculated. The reflection which occurs at the interface between the medium and free space is also investigated.
168 citations
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01 Jan 1939
TL;DR: In this article, an electromagnetic horn radiator with two opposite sides being flared, the other two being parallel, was studied experimentally at wavelengths between 40 and 100 centimeters, and the application to a straight-line blind-landing system for airplanes was discussed.
Abstract: An electromagnetic horn radiator two of whose opposite sides are flared, the other two being parallel, was studied experimentally at wavelengths between 40 and 100 centimeters. For comparison, measurements on parabolic reflectors and broadside arrays were also made. By virtue of its unusual freedom from secondary lobes and stray radiation, its ability to operate well over a broad band width, its simple construction, and its ease and stability of operation, the electromagnetic horn offers unique possibilities as a directive radiating system for microwave applications. These results and the application to a straight-line blind-landing system for airplanes are discussed.
53 citations