Thu, 24 Jul 2008 23:19:13 BST CiteULike: dcastros Eleftheriades http://www.citeulike.org/user/dcastro/author/Eleftheriades CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dcastro/article/3040303 <i>Antennas and Propagation Magazine, IEEE, Vol. 49, No. 2. (2007), pp. 34-51.</i><br /><br />Metamaterials are artificially engineered structures with unusual electromagnetic properties. In this article, we review the implementation of isotropic metamaterials that exhibit a negative permittivity and a negative permeability, thus leading to a negative index of refraction. Specifically, the article focuses on transmission-line metamaterials, which are planar structures comprising a network of distributed transmission lines loaded periodically with inductors, L, and capacitors, C, in a "high-pass" configuration. The periodic unit cell is much smaller than the wavelength, thus leading to an effective medium in which the lumped loading elements can be either discrete (chip) or printed. Based on such negative-refractive-index transmission-line (NRI-TL) metamaterials, several RF/microwave devices are presented, including microwave lenses that can overcome the diffraction limit, compact phase-shifting lines and associated broadband series-fed power dividers, electrically small antennas, antenna feed networks and baluns, backward leaky-wave antennas, and high-directivity coupled-line couplers and reflectometers. Enabling RF/microwave devices using negative-refractive-index transmission-line (NRI-TL) metamaterials GV Eleftheriades doi:10.1109/MAP.2007.379612 Antennas and Propagation Magazine, IEEE, Vol. 49, No. 2. (2007), pp. 34-51. 2008-07-24T15:53:31-00:00 2007 Antennas and Propagation Magazine, IEEE 49 2 34 51 devices metamaterial tl http://www.citeulike.org/user/dcastro/article/3040257 <i>Journal of Applied Physics, Vol. 92, No. 10. (2002), pp. 5930-5935.</i><br /><br />View This Record in Scopus Experimental verification of backward-wave radiation from a negative refractive index metamaterial Anthony Grbic George Eleftheriades Journal of Applied Physics, Vol. 92, No. 10. (2002), pp. 5930-5935. 2008-07-24T15:44:19-00:00 2002 Journal of Applied Physics 92 10 5930 5935 AIP metamaterial http://www.citeulike.org/user/dcastro/article/3015425 <i>Antenna Technology Small Antennas and Novel Metamaterials, 2006 IEEE International Workshop on (2006), pp. 241-244.</i> A Diplexer Based on the Spatial Filtering Property of Planar Anisotropic Transmission-Line Metamaterials JKH Wong KG Balmain GV Eleftheriades Antenna Technology Small Antennas and Novel Metamaterials, 2006 IEEE International Workshop on (2006), pp. 241-244. 2008-07-17T19:56:22-00:00 2006 Antenna Technology Small Antennas and Novel Metamaterials, 2006 IEEE International Workshop on 241 244 diplexer metamaterial tl http://www.citeulike.org/user/dcastro/article/3015422 <i>Antennas and Propagation International Symposium, 2007 IEEE (2007), pp. 4957-4960.</i><br /><br />This work demonstrates how certain properties of Negative-Refractive-Index Transmission-Line (NRI-TL) metamaterials can be utilized to miniaturize conventional microwave devices used to feed antennas. Specifically in NRI-TLs <i>small</i> values of the loading elements lead to <i>large</i> phase shifts per-unit-length, thus facilitating miniaturization. Using this principle, a compact NRI-TL branch-line coupler (85% area reduction) is presented. Moreover, a filter is presented with a performance that is similar to a four-stage coupled-line filter that is twice as long. Finally, these building blocks are combined to synthesize a compact NRI-TL diplexer that can separate two closely spaced frequencies (1.95 GHz / 2.03 GHz) with a minimum of 20 dB isolation. Compact Negative-Refractive-Index Transmission-Line (NRI-TL) coupler, filter and diplexer R Islam GV Eleftheriades doi:10.1109/APS.2007.4396657 Antennas and Propagation International Symposium, 2007 IEEE (2007), pp. 4957-4960. 2008-07-17T19:56:13-00:00 2007 Antennas and Propagation International Symposium, 2007 IEEE 4957 4960 crlh diplexer http://www.citeulike.org/user/dcastro/article/2938417 <i>Metamaterials for Microwave and (Sub) Millimetre Wave Applications: Photonic Bandgap and Double Negative Designs, Components and Experiments, 2003. IEE Seminar on (2003), pp. 12/1-12/8.</i> Enabling rfimicrowave devices using negative refractive-index transmission-line metamaterials GV Eleftheriades A Grbic AK Iyer MA Antoniades R Islam Metamaterials for Microwave and (Sub) Millimetre Wave Applications: Photonic Bandgap and Double Negative Designs, Components and Experiments, 2003. IEE Seminar on (2003), pp. 12/1-12/8. 2008-06-27T23:48:42-00:00 2003 Metamaterials for Microwave and (Sub) Millimetre Wave Applications: Photonic Bandgap and Double Negative Designs, Components and Experiments, 2003. IEE Seminar on 12/1 12/8 crlh metamaterial microwave http://www.citeulike.org/user/dcastro/article/2897761 <i>Microwave and Wireless Components Letters, IEEE, Vol. 15, No. 11. (2005), pp. 808-810.</i><br /><br />A metamaterial 1:4 series power divider that provides equal power split to all four output ports over a large bandwidth is presented, which can be extended to an arbitrary number of output ports. The divider comprises four nonradiating metamaterial lines in series, incurring a zero insertion phase over a large bandwidth, while simultaneously maintaining a compact length of /spl lambda//sub 0//8. Compared to a series power divider employing conventional one-wavelength long meandered transmission lines to provide in-phase signals at the output ports, the metamaterial divider provides a 165% increase in the input return-loss bandwidth and a 155% and 154% increase in the through-power bandwidth to ports 3 and 4, respectively. In addition, the metamaterial divider is significantly more compact, occupying only 2.6% of the area that the transmission line divider occupies. The metamaterial and transmission line dividers exhibit comparable insertion losses. A broadband series power divider using zero-degree metamaterial phase-shifting lines MA Antoniades GV Eleftheriades doi:10.1109/LMWC.2005.859007 Microwave and Wireless Components Letters, IEEE, Vol. 15, No. 11. (2005), pp. 808-810. 2008-06-16T07:03:20-00:00 2005 Microwave and Wireless Components Letters, IEEE 15 11 808 810 broadband divider metamaterial power http://www.citeulike.org/user/dcastro/article/2890645 <i>Antennas and Propagation International Symposium, 2007 IEEE (2007), pp. 4961-4964.</i><br /><br />In this paper, we present a design for a quad-band filter that is based entirely on NRI-TL metamaterial unit cells and exhibits narrow passbands with good selectivity. The multiple passbands of these cells are exploited to provide the overall characteristics of the device. The cells are printed in microstrip, resulting in a low-profile planar device. The device can also be designed as a tri-band or dual-band filter without changing its topology. A quad-band bandpass filter using negative-refractive-index transmission-line (NRI-TL) metamaterials M Studniberg GV Eleftheriades doi:10.1109/APS.2007.4396658 Antennas and Propagation International Symposium, 2007 IEEE (2007), pp. 4961-4964. 2008-06-13T07:01:43-00:00 2007 Antennas and Propagation International Symposium, 2007 IEEE 4961 4964 bandpass filter metamaterial http://www.citeulike.org/user/dcastro/article/2774491 <i>Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 10, No. 2. (2000), pp. 64-66.</i><br /><br />A single-layer CPW-fed active patch antenna oscillator at 2.76 GHz is presented. The patch antenna acts both as a resonator and a radiator. Electromagnetic coupling is utilized for providing the appropriate closed-loop positive feedback. The active antenna is built around a commercially available GaAs MMIC on a low-permittivity &epsiv;_r=2.33 Duroid 5870 substrate. The measured effective isotropic radiated power (EIRP) is 20 dBm, whereas the front-to-back ratio is about 12 dB with the cross-polarized fields better than -15 db. The measured phase noise is -87.5 dBc/Hz at a 100-kHz offset away from the carrier. The structure only requires a single substrate, is compatible with uniplanar technology, and results in a low-component count A single-layer CPW-fed active patch antenna KHY Ip TMY Kan GV Eleftheriades doi:10.1109/75.843102 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters], Vol. 10, No. 2. (2000), pp. 64-66. 2008-05-09T06:37:34-00:00 2000 Microwave and Guided Wave Letters, IEEE [see also IEEE Microwave and Wireless Components Letters] 10 2 64 66 active antenna patch http://www.citeulike.org/user/dcastro/article/2075640 <i>Metamaterials, Vol. 1, No. 2. (December 2007), pp. 53-61.</i><br /><br />Negative-refractive-index transmission-line (NRI-TL) metamaterials comprise transmission lines loaded periodically with series capacitors and shunt inductors, such that the phase flow and power flow are contra-directional on the lines. These NRI-TL media exhibit properties that can be utilized for miniaturizing microwave components and antennas. In this mainly review paper, a compact antenna, power divider and branch-line coupler are presented to demonstrate the miniaturization techniques enabled by NRI-TLs. Furthermore, a generalized NRI-TL is described that exhibits two left-handed and two right-handed bands. This can be exploited for realizing compact dual-band and quad-band RF/microwave components. This generalized NRI-TL can be designed to exhibit two distinct frequencies where the corresponding propagation constants vanish. Miniaturized microwave components and antennas using negative-refractive-index transmission-line (NRI-TL) metamaterials George Eleftheriades Rubaiyat Islam doi:10.1016/j.metmat.2007.08.001 Metamaterials, Vol. 1, No. 2. (December 2007), pp. 53-61. 2007-12-08T00:54:37-00:00 2007 Metamaterials 1 2 53 61 antenna metamaterial microwave http://www.citeulike.org/user/dcastro/article/1942337 <i>Microwave and Wireless Components Letters, IEEE, Vol. 14, No. 7. (2004), pp. 340-342.</i><br /><br />Two branch-line couplers are introduced that utilize a combination of regular microstrip (MS) and negative-refractive-index (NRI) lines. Interesting phase compensation (0/spl deg/ phase shift) at the output port and a choice of /spl plusmn/90/spl deg/ phase shift at the through port, with respect to the input, are possible. On the other hand, one of the dimensions of the coupler is significantly reduced, compared to a corresponding conventional branch-line coupler, but without any bandwidth degradation. Phase-agile branch-line couplers using metamaterial lines R Islam GV Eleftheriades doi:10.1109/LMWC.2004.829277 Microwave and Wireless Components Letters, IEEE, Vol. 14, No. 7. (2004), pp. 340-342. 2007-11-20T08:40:26-00:00 2004 Microwave and Wireless Components Letters, IEEE 14 7 340 342 branch-line coupler metamaterial http://www.citeulike.org/user/dcastro/article/1870043 <i>Microwave and Wireless Components Letters, IEEE, Vol. 13, No. 4. (2003), pp. 155-157.</i><br /><br />We present the complete band structure of a negative refractive index metamaterial based on the concept of dual transmission lines. The metamaterial is a two-dimensional (2-D) microstrip periodic structure that has cell dimensions much smaller than the wavelength of operation. It can therefore be considered as an effective medium. First, the dispersion characteristics of the metamaterial are explained by way of a 2-D loaded transmission line representation. Subsequently, full-wave analysis is utilized to reveal additional modes that can be excited in the metamaterial. Dispersion analysis of a microstrip-based negative refractive index periodic structure A Grbic GV Eleftheriades Microwave and Wireless Components Letters, IEEE, Vol. 13, No. 4. (2003), pp. 155-157. 2007-11-05T20:31:12-00:00 2003 Microwave and Wireless Components Letters, IEEE 13 4 155 157 metamaterial microstrip periodic structure http://www.citeulike.org/user/dcastro/article/1809534 <i>Antennas and Wireless Propagation Letters, Vol. 2 (2003), pp. 103-106.</i><br /><br />A compact one-dimensional phase shifter is proposed using alternating sections of negative refractive index (NRI) metamaterials and printed transmission lines (TL). The NRI metamaterial sections consist of lumped element capacitors and inductors, arranged in a dual TL (high-pass) configuration. By adjusting the NRI-medium lumped element values, the phase shift can be tailored to a given specification. Periodic analysis is applied to the structure and design equations are presented for the determination of the lumped element parameters for any arbitrary phase shift. To validate the design, various phase shifters are simulated and tested in coplanar waveguide (CPW) technology. It is demonstrated that small variations in the NRI-medium lumped element values can produce positive, negative or 0/spl deg/ phase shifts while maintaining the same short overall length. Thus, the new phase shifter offers some significant advantages over conventional delay lines: it is more compact in size, it exhibits a linear phase response around the design frequency, it can incur a phase lead or lag which is independent of the length of the structure and it exhibits shorter group delays. Compact linear lead/lag metamaterial phase shifters for broadband applications MA Antoniades GV Eleftheriades Antennas and Wireless Propagation Letters, Vol. 2 (2003), pp. 103-106. 2007-10-23T07:56:07-00:00 2003 Antennas and Wireless Propagation Letters 2 103 106 broadband coplanar metamaterial phase-shifter