Mai O. Sallam

Miniaturized RFID Tag Antenna Operating at 915 MHz

A novel miniaturized radio frequency identification (RFID) tag antenna is introduced in this letter. The antenna is designed to operate at 915 MHz. Its electrical size is (λ0/30)×(λ0/30), which makes it among the smallest antennas presented in literature. The new antenna has a “Vivaldi-like” aperture fed with a slot line coupled electromagnetically to a microstrip line. The aperture is loaded with a meander line. The new antenna is thoroughly investigated both theoretically and experimentally. It enjoys a number of appealing characteristics, such as compact size, low profile, flexible impedance tuning, good impedance bandwidth, omnidirectional radiation patterns, low cross-polarization level, and reasonable gain.

Micromachined On-Chip Dielectric Resonator Antenna Operating at 60 GHz

This paper presents a novel cylindrical dielectric resonator antenna (DRA) suitable for millimeter-wave (mm-wave) on-chip systems. The antenna was fabricated from a single high-resistivity silicon wafer via micromachining technology. The new antenna was characterized using HFSS and experimentally with good agreement been found between the simulations and experiment. The proposed DRA has good radiation characteristics, where its gain and radiation efficiency are 7 dBi and 79.35%, respectively. These properties are reasonably constant over the working frequency bandwidth of the antenna. The return loss bandwidth was 2.23 GHz, which corresponds to 3.78% around 60 GHz. The antenna was primarily a broadside radiator with -15dB cross-polarization level.

77-GHz MEMS brick-wall antenna fed by coupled microstrip lines

Micromachining technology is very attractive for integrated antennas as it offers efficient packaging, high radiation efficiency, wide impedance bandwidth, and less mutual coupling between antenna elements. These advantages are more difficult to be achieved using the conventional planar technology especially at high frequencies such as 77 GHz. Research carried out on MEMS antennas can be classified into two main categories. The first category features a flat antenna, such as patch, realized on a thin membrane [1]. The membrane is fabricated by etching silicon under the patch. This results in reducing the effective dielectric constant of the medium surrounding the antenna and consequently increases the bandwidth and radiation efficiency. The second category features a 3D antenna, such as horn or waveguide, realized by etching grooves in a number of silicon wafers [2]. The walls of these grooves are covered with metal. Each groove represents part of the desired 3D structure. The wafers are bonded together to form the complete antenna.

Integral equations formulation of plasmonic transmission lines

In this paper, a comprehensive integral equation formulation of plasmonic transmission lines is presented for the first time. Such lines are made up of a number of metallic strips with arbitrary shapes and dimensions immersed within a stack of planar dielectric or metallic layers. These lines support a number of propagating modes. Each mode has its own phase constant, attenuation constant, and field distribution. The presented integral equation formulation is solved using the Method of Moments (MoM). It provides all the propagation characteristics of the modes. The new formulation is applied to a number of plasmonic transmission lines, such as: single rectangular strip, horizontally coupled strips, vertically coupled strips, triangular strip, and circular strip. The numerical study is performed in the frequency (wavelength) range of 150-450 THz (0.66-2.0 μm). The results of the proposed technique are compared with those obtained using Lumerical mode solution, and CST. Very good agreement has been observed. The main advantage of the MoM is its intrinsic speed for this type of problem compared to general purpose solvers.

Plasmonic Grid Array of Gold Nanorods for Point-to-Point Optical Communications

A novel wire-grid array of nanorods is introduced. The array consists of five gold radiating rods and four gold perpendicular connecting rods. Each rod represents a plasmonic transmission line supporting single Surface Plasmon Polariton mode guided to the interface between the metal and surrounding dielectric. The propagation characteristics of this single strip plasmonic transmission line are studied using an integral equations formulation solved using the Method of Moments. The new array is designed for operation at a wavelength of 1.55 μm, which is commonly used by optical communication systems. The overall physical and electrical sizes of the array are (0.68-by-1.05 μm) and (λg-by-3λg/2), respectively. The maximum directivity of the proposed wire-grid nantenna array on top of a substrate with refractive index of 2 reaches 15.24 dBi. The proposed wire-grid nantenna array has a symmetric radiation pattern with reasonable side-lobe-level and extremely low cross-polarization level.

Dendritic optical antennas: scattering properties and fluorescence enhancement

With the development of nanotechnologies, researchers have brought the concept of antenna to the optical regime for manipulation of nano-scaled light matter interactions. Most optical nanoantennas optimize optical function, but are not electrically connected. In order to realize functions that require electrical addressing, optical nanoantennas that are electrically continuous are desirable. In this article, we study the optical response of a type of electrically connected nanoantennas, which we propose to call “dendritic” antennas. While they are connected, they follow similar antenna hybridization trends to unconnected plasmon phased array antennas. The optical resonances supported by this type of nanoantennas are mapped both experimentally and theoretically to unravel their optical response. Photoluminescence measurements indicate a potential Purcell enhancement of more than a factor of 58.

Wideband CPW-Fed Flexible Bow-Tie Slot Antenna for WLAN/WiMax Systems

A bow-tie antenna based on a slot configuration in a single metal sheet on top of a very thin flexible substrate is introduced. The antenna is constructed from two slotted right-angle triangles fed by a coplanar waveguide transmission line. The topology is very simple and extremely easy to tune in order to reach the proper characteristics after mounting on a supporting structure. A prototype is designed, fabricated, and characterized experimentally. The tunability is proven by considering both the version in free space and the version for use on a brick wall. Measurements demonstrate good agreement with simulations. Both versions cover the wireless local area network (2.4 and 3.65 GHz) and WiMax (2.3, 2.5, and 3.5 GHz) spectra, with an overall impedance bandwidth of 1.79 GHz (57.7%) and 1.46 GHz (49.7%), respectively. The radiation of the antenna is bidirectional with maximum gains of 6.30 and 5.09 dBi for the free space and brick wall versions, respectively.

Corporate array of micromachined dipoles on silicon wafer for 60 GHz communication systems

In this paper, an antenna array operating at 60 GHz and realized on 0.675 mm thick silicon substrate is presented. The array is constructed using four micromachined half-wavelength dipoles fed by a corporate feeding network. Isolation between the antenna array and its feeding network is achieved via a ground plane. This arrangement leads to maximizing the broadside radiation with relatively high front-to-back ratio. Simulations have been carried out using both HFSS and CST, which showed very good agreement. Results reveal that the proposed antenna array has good radiation characteristics, where the directivity, gain, and radiation efficiency are around 10.5 dBi, 9.5 dBi, and 79%, respectively.

77 GHz MEMS antennas on high-resistivity silicon for linear and circular polarization

Two new MEMS antennas operating at 77 GHz are presented in this paper. The first antenna is linearly polarized. It possesses a vertical silicon wall that carries a dipole on top of it. The wall is located on top of silicon substrate covered with a ground plane. The other side of the substrate carries a microstrip feeding network in the form of “U-turn” that causes 180° phase shift. This phase-shifter feeds the arms of the dipole antenna via two vertical Through-Silicon Vias (TSVs) that go through the entire wafer. The second antenna is circularly polarized and formed using two linearly polarized antennas spatially rotated with respect to each other by 90° and excited with 90° phase shift. Both antennas are fabricated using novel process flow on a single high-resistivity silicon wafer via bulk micromachining. Only three processing steps are required to fabricate these antennas. The proposed antennas have appealing characteristics, such as high polarization purity, high gain, and high radiation efficiency.

Generalized mode solver for plasmonic transmission lines embedded in layered media based on the Method of Moments

Abstract This paper presents an integral equation formulation for the calculation of the propagation characteristics of plasmonic transmission lines embedded within a multi-layered structure. The Method of Moments (MoM) technique is adopted in this paper due to its superior advantages over other techniques including the finite difference and finite element methods. Plasmonic transmission lines consist of a number metallic strips of arbitrary shapes immersed within a stack of planar dielectric or metallic layers. These transmission lines can support one or more mode, each of which has its characteristic mode profile and it propagates with a certain propagation and attenuation constants. The developed solver is tested for different plasmonic transmission line topologies surrounded by various layered media. The obtained results are compared to CST commercial software for verification. Very good agreement between the proposed solver and CST has been observed. The developed MoM solver requires much smaller number of unknowns if compared with those based on Finite Difference Time Domain (FD-TD) or Finite Element Method (FEM) such as Lumerical and CST.