A novel type of microstrip antenna is proposed for compact wideband wireless applications. The antenna is composed of six unit cells of left-handed metamaterial (LHM) and a dipole element. The dipole is directly connected to three of six LHM unit cells, which are arranged in a 2 times 3 antenna array form. In this aspect, the proposed antenna is regarded as LHM loaded dipole antenna. The antenna is matched with a stepped impedance transformer and rectangular slot in the truncated ground plane. The coupled LH resonances and simultaneous excitation of different sections of unit cells and dipole result into broad bandwidth. The proposed antenna has a maximum gain of -1 dBi at 2.5 GHz. The measured return loss indicates 63% bandwidth for |S11| < -10 dB over the band of 1.3-2.5 GHz. The overall size of LHM loaded antenna is lambda0/2.87 times lambda0/11.27 times lambda0/315.80 at the center frequency. The radiation of the electrically small LHM unit cells is also demonstrated by the simulated radiation pattern, which is an important concept for the antenna miniaturization.

Broadband Microstrip Antenna With Left-Handed Metamaterials

We experimentally demonstrated an alternative approach of invisibility cloaking that can combine technical advantages of all current major cloaking strategies in a unified manner and thus can solve bottlenecks of individual strategies. A broadband cylindrical invisibility cloak in free space is designed based on scattering cancellation (the approach of previous plasmonic cloaking), and implemented with anisotropic metamaterials (a fundamental property of singular-transformation cloaks). Particularly, nonsuperluminal propagation of electromagnetic waves, a superior advantage of non-Euclidian-transformation cloaks constructed with complex branch cuts, is inherited in this design, and thus is the reason of its relatively broad bandwidth. This demonstration provides the possibility for future practical implementation of cloaking devices at large scales in free space.

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Experimental demonstration of a free-space cylindrical cloak without superluminal propagation.

This paper presents a compact triple band antenna for the frequency bands 2.4, 3.5 and 5 GHz. These bands are assigned to the IEEE 802.11a/b/g and IEEE 802.16e standards. The resonant modes for WLAN, WiMAX bands are achieved by employing a rectangular slot and a metamaterial inspired split ring structure. The extraction procedure of negative permeability for the proposed split ring resonator is discussed in detail. Tunability between the WLAN and WiMAX standards is demonstrated by using a single PIN diode. The proposed antenna with a compact size of 27 mm × 25 mm is fabricated and tested. The triple band antenna yields a −10 dB impedance bandwidth of about 18.6%, 4.3% and 40.3% in 2.4, 3.5 and 5 GHz bands respectively. Stable radiation patterns with low cross polarization and high average antenna gain of 2.46 dBi are observed for the operating bands.

A compact metamaterial inspired triple band antenna for reconfigurable WLAN/WiMAX applications

In this paper, a compact metamaterial multiband antenna is proposed for wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX) and international telecommunication union (ITU) band applications using a modified Triangular Split Ring Resonator (TSRR). In this work, we designed a modified TSRR with metamaterial property to obtain desirable negative permeability bands that help in accommodating all three frequency bands of interest in a single device. This approach leads to the considerable reduction of the device structure. The overall dimension of the proposed antenna structure has a compact size of 25.7 × 23.2 × 1.6 mm 3 and covers specific bands from the frequency spectra of 2.4/5.2/5.8, 3.5, and 8.2 GHz for WLAN, WiMAX, and ITU, respectively, with uniform radiation characteristics. The designed antenna structure is simulated using the High Frequency Structural Simulator (HFSS), and a prototype is developed and tested. The detailed analysis of the results obtained is presented. It is determined that the performance of the proposed antenna is superior to that of the existing antennas in the literature.

A compact metamaterial multiband antenna for WLAN/WiMAX/ITU band applications

This paper presents a miniaturized ultra wideband (UWB) antenna with metamaterial for WLAN and WiMax applications. For miniaturization of UWB antenna resonating 3.1–10.6 is designed Ghz using fractalization of the radiating edge and slotted ground structure approach. A miniaturization of active patch area and antenna volume is achieved up to 63.48% and 42.24% respectively, with respect to the conventional monopole UWB antenna. This antenna achieves a 143% impedance bandwidth covering the frequency band from 2.54GHz to 15.36GHz under simulation and 132% (2.95–14.28 GHz) in measurement. The electrical dimension of this antenna is 0.32λ × 0.32λ (38mm×38mm) at lower frequency of 2.54GHz. As per IEEE 802.11a/b/g and IEEE 802.16e standards, WLAN (2.4–2.5 GHz, 5.150–5.250 GHz, 5.725–5.825 GHz), WiMAX (3.3–3.8 GHz) bands are achieved by using slotted ground structure and metamaterial rectangular split ring resonator. The proposed antenna is fabricated on FR4 substrate of thickness 1.6mm and a dielectric constant 4.3 and tested. The proposed antenna yields a −10 dB impedance bandwidth of about 11.1% (2.39–2.67 GHz), 59.1% (2.87–5.28 GHz) and 7.4% (5.58–6.01 GHz) under simulation and 4.5% (2.41–2.52 GHz), 51.1% (3.12–5.26 GHz) and 3.8% (5.69– 5.91GHz) in measurement for 2.4, 3.5 & 5 and 5.8GHz bands respectively. Stable radiation patterns with low cross polarization, high average antenna gain of 3.02 dBi under simulation and 2.14 dBi in measurement and measured peak average radiation efficiency of 76.6% are observed for the operating bands. Experimental results seem in good agreement with the simulated ones of the proposed antenna.

https://www.jpier.org/pierb/pierb65/05.15112703.pdf

Miniaturized Slotted Ground UWB Antenna Loaded with Metamaterial for WLAN and WiMAX Applications

A waveguide-based retrieval method for measuring complex permittivity and permeability tensors of metamaterials is presented. In the proposed scheme, multiple independent sets of scattering data for the material under test with different orientations are measured in the frequency range corresponding to the dominant TE(10) mode. The method is applied to various metamaterials and shows its effectiveness in the effective parameters extraction.

Qin Jiang

Papers

Experimental retrieval of the effective parameters of metamaterials based on a waveguide method.