Biao Peng

Compact Quad-Mode Bandpass Filter Based on Quad-Mode DGS Resonator

In this letter, a quad-mode bandpass filter is built up based on a novel quad-mode defected ground structure (DGS) resonator which has two symmetric planes. The odd-/even-mode theory is applied to analyze the operating principle of the four resonances with their equivalent circuit models. The four resonances can be effectively tuned by adjusting the corresponding dimensions. The fabricated filter has a center frequency of 2.45 GHz and a wide stopband up to 7.8 GHz with a rejection below -30 dB, which extends to at least 30 GHz below -16 dB. Particularly, the filter exhibits an excellent attenuation slope of 302 dB/GHz in the upper passband transition.

Triple band-notched slot planar inverted cone antenna for UWB applications

A novel triple band-notched slot planar inverted cone antenna (SPICA) is proposed for UWB applications. The unnotched ultrawideband antenna is composed of a cone shaped radiating patch and a wide circularly slot on the ground plane. To obtain anti-interference characteristics, an elliptical complementary split ring resonator (ECSRR) was etched in the radiating patch and a parasitic V shaped strip was added adjacent to the upper edges of the cone shaped patch. This will result in triple notched bands at WiMAX, WLAN and X band satellite communication downlinks. The results show the antenna has a wide impedance bandwidth of 140% for SWR <; 2 from 2.2 to 12 GHz with triple undesired bands (WiMAX, WLAN and X-band satellite communication downlinks) rejected. Other advantages, such as stable omnidirectional radiation patterns, easy fabrication as well as compact size make the design applicable to UWB applications.

Manipulating of Different-Polarized Reflected Waves with Graphene-based Plasmonic Metasurfaces in Terahertz Regime

A graphene-based plasmonic metasurface which can independently control different polarized electromagnetic waves with reasonably small losses in terahertz regime is proposed and demonstrated in this paper. This metasurface is composed of graphene based elements. Owing to anisotropic plasmonic resonance of the graphene-based elements, the reflected phases and magnitudes of orthogonally polarized waves can be independently controlled by varying dimensions of the element. Four types of graphene-based plasmonic metasurfaces with different reflected phases distributions are synthesized and simulated, exhibiting diverse functions such as polarized beam splitting, beam deflection, and linear-to-circular polarization conversion. The simulation results demonstrate excellent performances as theoretical expectation. The proposed graphene-based plasmonic metasurface can be applied to realize extremely light-weight, ultra-compact, and high-performances electromagnetic structures for diverse terahertz applications.

Three-Dimensional Simultaneous Arbitrary-Way Orbital Angular Momentum Generator Based on Transformation Optics

In wireless communications, people utilize the technology of diversity against multipath fading, so as to improve the reliability of communication equipment. One of the long-standing problems in diversity antennas is the limited number of diversity in a certain space. In this paper, we provide a solution to this issue by a three-dimensional (3D) simultaneous arbitrary-way orbital angular momentum (OAM) generator (3D SAWOG) based on transformation optics. The proposed 3D SAWOG consists of a metamaterial block and a group of transformation cylinders, by which arbitrary-way planar wavefronts can be converted to helical wavefronts with various topological charges simultaneously. The 2D four-way OAM generator and the 3D SAWOG are analyzed, designed, and simulated. The simulation results validate the performance of a 3D SAWOG successfully, indicating that the proposed model possess a high mode purity and expansibility. The SAWOG can be used as a novel diversity antenna array due to the orthogonal property among different modes, which could provide more degrees of freedom than traditional dual-polarization antennas, further improving the reliability of the communication systems.

CPW-fed dual-/tri-band slot antenna based on multi-mode slot line resonator

In this paper, a dual-band CPW-fed antenna is designed with wide bandwith (BW) tunability. By using the odd-/even-mode theory, the resonant characteristics of the radiating element is vividly analyzed based on equivalent circuit models and design curves. There are four resonances, the 1st of which performs as a parasitic resonance. The 2nd resonance produces the first operating band while the 3rd and 4th resonances construct the second band. By spliting the second operating band into two narrow bands, a tri-band antenna can be produced. The fabricated dual-band antenna works at 2.39 GHz and 5.26 GHz with BW of 14.9 % and 23.5 %, respectively. The mid-band reflection coefficient in each band is better than - 18 dB.

CPW-fed dual-band MIMO antenna based on harmonic resonance with high isolation

In this paper, a dual-band CPW-fed MIMO antenna is designed and analyzed. Fundamental resonance of the coplanar stepped impedance resonator (CSIR) produces the 1st operating band, while its harmonic resonance and the resonance of the rectangular slot line resonator (RSLR) construct the 2nd band. The port-to-port isolation within the 2nd band is high since it works at the harmonic resonant frequency of the CSIR. The bandwidth of the 2nd band can be easily tuned in a very wide range by adjusting the resonant frequency of the RSLR. Finally, a hexagon 3-port dual-band MIMO antenna is designed and fabricated with isolation higher than 30 dB and 40 dB within the two operating bands, respectively.

Conformal array design on arbitrary polygon surface with transformation optics

A transformation-optics based method to design a conformal antenna array on an arbitrary polygon surface is proposed and demonstrated in this paper. This conformal antenna array can be adjusted to behave equivalently as a uniformly spaced linear array by applying an appropriate transformation medium. An typical example of general arbitrary polygon conformal arrays, not limited to circular array, is presented, verifying the proposed approach. In summary, the novel arbitrary polygon surface conformal array can be utilized in array synthesis and beam-forming, maintaining all benefits of linear array.

Discretization of an square electromagneic cloak based on transformation optics

Existing discrete electromagnetic cloaks are often limited to circular shape and always based on one dimensional discretization of radius variable in cylindrical coordinates. In this paper, we proposed a two dimensional (2D) discrete square invisible cloak which really does not require any continuous constitutive material parameters. The discrete square cloak consists of several homogeneous blocks, and they are discretized from the original transform medium whose material parameters are often continuous spatial functions of both x and y variables in Cartesian coordinates. With proper design of numbers of blocks, we demonstrated the scattering properties of the proposed cloaking structure through rigorous analysis of the scattered electromagnetic fields. The proposed cloaking structure could be possibly realized, therefore may lead to a practical path to an experimental demonstration of electromagnetic cloaking.

Alumina ceramic slot antenna for UHF RFID tag embedded in vehicles

To address the problem of metallic interferences in vehicular RFID (Radio-frequency identification) applications, this paper proposes a novel alumina ceramic slot tag antenna (ACSTA). The proposed antenna consists of a grounded thin alumina ceramic substrate and a slotted top layer rectangular patch with all four shorting edges. This structure can be equivalent to a horizontal magnetic current flow above a large ground plane, so an excellent radiation performance is achieved according to the electromagnetic image theory. Meanwhile, due to the existence of the ground plane, the influences of the interferential metallic objects behind the ground to the tag antenna impedance can be maximally reduced. This ACSTA combined with a commercial chip is fabricated and measured, and the thickness of the novel tag is only 1mm. Simulation and measurement results show that the proposed antenna has an excellent performance, and the operating frequency band of the ACSTA covers U.S. legal UHF RFID (902MHz-928MHz) band, and so it is a quite suitable candidate for vehicular RFID applications.