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Journal ArticleDOI

Assessment of the Performance of a Metamaterial Spacer in a Closely Spaced Multiple-Antenna System

TL;DR: In this article, a metamaterial spacer composed of spiral resonators and narrow metal strips was tested to operate like a bidirectional artificial magnetic conductor (AMC) reflector at 2.45 GHz.
Abstract: A metamaterial spacer composed of spiral resonators (SRs) and narrow metal strips has been tested to operate like a bidirectional artificial magnetic conductor (AMC) reflector at 2.45 GHz. The performance of the spacer has also been evaluated in a closely spaced multiple-antenna system applied to successfully increase the transmission capacity of a commercial wireless IEEE 802.11b router.
Citations
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Journal ArticleDOI
TL;DR: By incorporating the meta-structures into the array configuration, the isolation levels between adjacent radiating elements in both the E- and H-planes orientations are improved by as much as 7.15 dB.
Abstract: A mutual coupling reduction strategy that employs meta-structures is introduced for wideband, dual-polarized, high-density, planar, and patch antenna arrays The meta-structures consist of two types of resonators: grounded capacitively loaded loops (GCLLs) and $\pi$ -shaped elements By incorporating the meta-structures into the array configuration, the isolation levels between adjacent radiating elements in both the E- and H-planes orientations are improved by as much as 715 dB The surface current distribution behaviors of the array with only the GCLLs and with only the $\pi$ -shaped elements are investigated thoroughly to explain the mutual coupling reduction mechanisms A proof-of-concept array was constructed and tests were performed that validate the reported design principles and simulation results

90 citations


Cites background from "Assessment of the Performance of a ..."

  • ...ded circuit resonators [21], capacitively loaded loop (CLL) resonators [22], waveguide-based resonators [23], composite metamaterials [24], [25], artificial magnetic conductor metastructures [26], [27], double-layer mushroom structures [28], and coplanar strip walls [29]....

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Journal ArticleDOI
TL;DR: In this article, a two-element triple-band multiple-input multiple-output (MIMO) antenna with reflective type metasurface (MS) for enhancing the gain, isolation and impedance bandwidth (IBW) is presented.
Abstract: In this work, a compact two-element triple-band multiple-input multiple-output (MIMO) antenna loaded with reflective type metasurface (MS) for enhancing the gain, isolation and impedance bandwidth (IBW) is presented. The two-element radiator antenna consists of a microstrip feed line on the upper side of the substrate and defected ground structure (DGS) on the backside on which multiple slots are etched for obtaining triple-band antenna performance. Due to DGS loading, the entire dimensions of the single radiator antenna are reduced to 22 × 22 × 1.6 mm3 with smaller electrical dimensions of 0.17λ 0 × 0.17λ 0 × 0.012λ 0 at the first resonating frequency. The proposed two-port MIMO antenna with MS operates at 2.36–2.50, 3.43–3.50 and 5.15–5.88 GHz with percentage bandwidths of 5.76, 2.02 and 13.22% for the three operating bands. Due to MS loading, a gain improvement of 5.49, 4.57 and 0.80 dBi is noticed with a maximum gain of 3.98, 5.25 and 2.66 dBi is obtained at the three operating frequencies of 2.46, 3.51 and 5.32 GHz, respectively. The intended antenna is appropriate for working in IEEE 802.11 b/g/n (2.4–2.484 GHz) WLAN, IEEE 802.11 a/h/j (5.15–5.825 GHz) WLAN, and IEEE 802.16e (3.4–3.5 GHz) WiMAX wireless applications.

19 citations

Journal ArticleDOI
TL;DR: In this article, a single negative magnetic (SNG) metamaterial (MTM) insulator is designed to reduce mutual coupling between high profile monopole antennas to achieve high decoupling efficiency.
Abstract: A novel single-negative magnetic (SNG) metamaterial (MTM) insulator is designed to reduce mutual coupling between high-profile monopole antennas. As a kind of metamaterials, the proposed SNG MTM-resonator utilized concentric rings embedded complementary metal structures. Then, an insulator is achieved with a highly compact structure. The band-gap of the insulator is attributed to the negative permeability of the magnetic resonance. A well-engineered MTM-resonator is then embedded in between a high-profile monopole antenna array for coupling reduction. The antenna array is designed, fabricated, and measured. Both numerical and experimental results indicate a mutual coupling reduction of more than 17 dB. The 20 dB isolation bandwidth about 16% is obtained. The proposed prescription with electrically small dimensions and high decoupling efficiency opens an avenue to new types of high-profile antennas with super performances.

8 citations

Journal ArticleDOI
11 Oct 2017
TL;DR: In this paper, it was shown that while the ground plane has little impact on the resonance frequency and impedance bandwidth of patch antennas or metamaterial-inspired three-dimensional magnetic EZ antennas, it has a huge impact on their directivity.
Abstract: When an electrically small antenna is conceived, designed, simulated, and tested, the main emphasis is usually placed immediately on its impedance bandwidth and radiation efficiency. All too often it is assumed that its directivity will only be that of a Hertzian dipole and, hence, its directivity becomes a minor consideration. This is particularly true if such a compact antenna radiates in the presence of a large ground plane. Attention is typically focused on the radiator and its size, while the ground plane is forgotten. This has become a too frequent occurrence when antennas, such as patch antennas that have been augmented with metamaterial structures, are explored. In this paper, it is demonstrated that while the ground plane has little impact on the resonance frequency and impedance bandwidth of patch antennas or metamaterial-inspired three-dimensional magnetic EZ antennas, it has a huge impact on their directivity performance. Moreover, it is demonstrated that with both a metamaterial-inspired two-element array and a related Huygens dipole antenna, one can achieve broadside-radiating electrically small systems that have high directivities. Several common and original designs are used to highlight these issues and to emphasize why a fundamental figure of merit such as directivity should never be overlooked.

6 citations

Journal ArticleDOI
TL;DR: In this paper , the concept and implementation of a compact dual-band microstrip slot antenna and its four-unit multiple-input-multiple-output (MIMO) implementation for sub-6 GHz utilizations is described.
Abstract: |This paper describes the concept and implementation of a compact dual-band microstrip slot antenna and its four-unit multiple-input{multiple-output (MIMO) implementation for sub-6 GHz utilizations. The proposed structure comprises a 50 ohm microstrip monopole on the top side with a defective ground structure (DGS) having semicircular and rectangular slots. This quad-element MIMO antenna has a size of 60 (cid:2) 60 (cid:2) 1 : 6 mm 3 . The proposed antenna provides wide impedance bandwidths of 23.7% (2.42 GHz to 3.07 GHz) for the (cid:12)rst band and 42.2% (4.14 GHz to 6.37 GHz) for the second band with a mutual coupling value less than (cid:0) 34 dB for the two bands. The antenna also provides a low envelope correlation coefficient, good antenna gain, and acceptable radiation efficiency across the frequency ranges.

3 citations

References
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Book
01 Jan 1982
TL;DR: The most up-to-date resource available on antenna theory and design as mentioned in this paper provides an extended coverage of ABET design procedures and equations making meeting ABET requirements easy and preparing readers for authentic situations in industry.
Abstract: The most-up-to-date resource available on antenna theory and design Expanded coverage of design procedures and equations makes meeting ABET design requirements easy and prepares readers for authentic situations in industry New coverage of microstrip antennas exposes readers to information vital to a wide variety of practical applicationsComputer programs at end of each chapter and the accompanying disk assist in problem solving, design projects and data plotting-- Includes updated material on moment methods, radar cross section, mutual impedances, aperture and horn antennas, and antenna measurements-- Outstanding 3-dimensional illustrations help readers visualize the entire antenna radiation pattern

14,065 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the performance of using multi-element array (MEA) technology to improve the bit-rate of digital wireless communications and showed that with high probability extraordinary capacity is available.
Abstract: This paper is motivated by the need for fundamental understanding of ultimate limits of bandwidth efficient delivery of higher bit-rates in digital wireless communications and to also begin to look into how these limits might be approached. We examine exploitation of multi-element array (MEA) technology, that is processing the spatial dimension (not just the time dimension) to improve wireless capacities in certain applications. Specifically, we present some basic information theory results that promise great advantages of using MEAs in wireless LANs and building to building wireless communication links. We explore the important case when the channel characteristic is not available at the transmitter but the receiver knows (tracks) the characteristic which is subject to Rayleigh fading. Fixing the overall transmitted power, we express the capacity offered by MEA technology and we see how the capacity scales with increasing SNR for a large but practical number, n, of antenna elements at both transmitter and receiver. We investigate the case of independent Rayleigh faded paths between antenna elements and find that with high probability extraordinary capacity is available. Compared to the baseline n = 1 case, which by Shannon‘s classical formula scales as one more bit/cycle for every 3 dB of signal-to-noise ratio (SNR) increase, remarkably with MEAs, the scaling is almost like n more bits/cycle for each 3 dB increase in SNR. To illustrate how great this capacity is, even for small n, take the cases n = 2, 4 and 16 at an average received SNR of 21 dB. For over 99% of the channels the capacity is about 7, 19 and 88 bits/cycle respectively, while if n = 1 there is only about 1.2 bit/cycle at the 99% level. For say a symbol rate equal to the channel bandwith, since it is the bits/symbol/dimension that is relevant for signal constellations, these higher capacities are not unreasonable. The 19 bits/cycle for n = 4 amounts to 4.75 bits/symbol/dimension while 88 bits/cycle for n = 16 amounts to 5.5 bits/symbol/dimension. Standard approaches such as selection and optimum combining are seen to be deficient when compared to what will ultimately be possible. New codecs need to be invented to realize a hefty portion of the great capacity promised.

10,526 citations

Journal ArticleDOI
TL;DR: In this paper, a new type of metallic structure has been developed that is characterized by having high surface impedance, which is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements and distributed in a two-dimensional lattice.
Abstract: A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.

4,264 citations


"Assessment of the Performance of a ..." refers background in this paper

  • ...Slits on the ground plane [5] or electromagnetic band-gap structures [6] have been used to reduce mutual coupling by suppressing surface wave propagation....

    [...]

Journal ArticleDOI
TL;DR: This article provides exact upper bounds on the throughput of any node in a WMN for a given topology and the set of active nodes, and shows that for WMNs the throughput decreases as O(1/n), where n is the total number of nodes in the network.
Abstract: Wireless mesh networks are an alternative technology for last-mile broadband Internet access. In WMNs, similar to ad hoc networks, each user node operates not only as a host but also as a router; user packets are forwarded to and from an Internet-connected gateway in multihop fashion. The meshed topology provides good reliability, market coverage, and scalability, as well as low upfront investments. Despite the recent startup surge in WMNs, much research remains to be done before WMNs realize their full potential. This article tackles the problem of determining the exact capacity of a WMN. The key concept we introduce to enable this calculation is the bottleneck collision domain, defined as the geographical area of the network that bounds from above the amount of data that can be transmitted in the network. We show that for WMNs the throughput of each node decreases as O(1/n), where n is the total number of nodes in the network. In contrast with most existing work on ad hoc network capacity, we do not limit our study to the asymptotic case. In particular, for a given topology and the set of active nodes, we provide exact upper bounds on the throughput of any node. The calculation can be used to provision the network, to ensure quality of service and fairness. The theoretical results are validated by detailed simulations.

614 citations

Journal ArticleDOI
TL;DR: In this article, a simple ground plane structure that can reduce mutual coupling between closely packed antenna elements is proposed and studied, which consists of a slitted pattern, without via's, etched onto a single ground plane and it is therefore low cost and straightforward to fabricate.
Abstract: A simple ground plane structure that can reduce mutual coupling between closely-packed antenna elements is proposed and studied. The structure consists of a slitted pattern, without via's, etched onto a single ground plane and it is therefore low cost and straightforward to fabricate. It is found that isolations of more than -20 dB can be achieved between two parallel individual planar inverted-F antennas (PIFAs) sharing a common ground plane, with inter-antenna spacing (center to center) of 0.116 lambdao and ground plane size 0.331lambdao 2. At 2.31 GHz it is demonstrated that this translates into an edge to edge separation between antennas of just 10 mm. Similarly the structure can be applied to reduce mutual coupling between three or four radiating elements. In addition the mutual coupling between half wavelength patches and monopoles can also be reduced with the aid of the proposed ground plane structure. Results of parametric studies are also given in this paper. Both simulation and measurement results are used to confirm the suppression of mutual coupling between closely-packed antenna elements with our slitted ground plane.

586 citations


"Assessment of the Performance of a ..." refers background in this paper

  • ...Slits on the ground plane [5] or electromagnetic band-gap structures [6] have been used to reduce mutual coupling by suppressing surface wave propagation....

    [...]