Modifying conventional microwave antenna designs using fine scale structures and nanomaterials

This paper investigates the possibility of designing and fabricating microwave antennas using metallic nanomaterials. Specifically, we will consider modifying the structure of conventional designs including dipoles, loops and apertures. FDTD simulations are used to examine these modified structures. Due to the prohibitive computational requirements of modelling nanoscale objects on a millimetre scale, the structures are approximated using larger scale objects. However, cell sizes down to 2¿m have been considered. The results show that the frequency can be decreased. However, typically the bandwidth decreases

A miniaturized 3 dimensional bandpass frequency selective surface

A planar bandpass frequency selective surface (FSS) is proposed along with an alternative 3D element design with the intent of miniaturizing the unit cell. The two structures are simulated in CST and compared. Such techniques show the potential of using 3D elements in FSS design to miniaturize the structure for space constrained applications

Microwave aperture antennas using nanomaterials

In this paper, computer simulations are used to investigate the concept of designing microwave aperture antennas, potentially fabricated using metallic nanomaterials. Nanomaterials are considered as they facilitate fabrication and electromagnetic advantages. Aperture radiating structures have been excited by a plane wave in a microstrip line. The aperture was modified with the addition of fine scale structures; vertical strips shorter than the height of the aperture. These initial simulation results have shown that these fine structures inside the aperture can decrease the resonance frequency at the expense of the bandwidth

Nano-metamaterial antennas at microwave frequencies

This paper examines the possibility of creating novel microwave frequency antennas by suitably arranging metallic / dielectric nanoparticles. Simulation results show that the antenna must be composed of ≥ 99% metal (<1 % gaps)

Optically reconfigurable balanced dipole antenna

In this paper, a new design for an optically reconfigurable printed dipole antenna is presented. A wideband coplanar waveguide (CPW) to coplanar strip (CPS) transition is used to feed the printed dipole. Two optically activated silicon switches, controlled using fibre optic cables and near infra-red laser diodes, are placed on small gaps in the dipole arms. The switches enable the dipole length to be optically controlled, thus facilitating frequency switching. Measured return loss results that compare well to the simulated values are also presented, showing a frequency shift of 10.5%

Reconfigurable antenna using photoconducting switches

This paper presents a design for an optically reconfigurable printed dipole antenna. A wideband coplanar waveguide (CPW) to coplanar stripline (CPS) transition is used to feed the balanced printed dipole. Two silicon photo switches are placed on small gaps in both dipole arms equidistant from the centre feed. Light from two infra-red laser diodes channelled through fibre optic cables is applied to the switches. With the gaps in the dipole bridged, the antenna resonates at a lower frequency. Measured return loss results that compare well to the simulated values are also presented, showing a frequency shift of nearly 40%. The change in bore-sight gain along with radiation patterns are also presented

Metamaterial with polarization and direction insensitive resonant transmission response mimicking electromagnetically induced transparency

We report on a planar metamaterial, the resonant transmission frequency of which does not depend on the polarization and angle of incidence of electromagnetic waves. The resonance results from the excitation of high-Q antisymmetric trapped current mode and shows sharp phase dispersion characteristic to Fano-type resonances of the electromagnetically induced transparency phenomenon

Antenna frequency and beam reconfliguring using photoconducting switches

This paper presents the use of photoconducting switches in antennas for reconfiguring operating frequencies and radiation patterns. It has also been demonstrated that these switches can be used in optically controlled phase shifters. A frequency shift of 40% is achieved with a dipole antenna and an array of patch antennas show beam scanning covering 30deg

Additively manufactured artificial materials with metallic meta-atoms

The paper presents the analysis and fabrication of artificial materials with metallic cuboid inclusions (termed here as meta-atoms) in a dielectric host material. These synthetic materials or metamaterials have been additively manufactured with a fused deposition modelling (FDM) 3D-printer. The effective permittivity and permeability have been numerically analyzed using the Maxwell-Garnett and Lewin’s approximation. Simulations and measurements have shown good agreement with analytical calculations. The anisotropy of the heterogeneous mixture due to the orientation of the meta-atoms has been demonstrated. The effective permittivity has been increased by the presence of the meta-atoms, which has the potential of producing 3D-printing metamaterials with tailored electromagnetic properties

Designing microwave patch antennas using heterogeneous substrates

This paper introduces the concept of designing microwave patch antennas by creating synthetic heterogeneous substrates with small scale inclusions. These inclusions embedded in a host dielectric can be used to control the dielectric properties and create bespoke effective permittivity values. Heterogeneous patch antennas at 2.4GHz are simulated in this paper. By deliberately mapping the permittivity values to the electric fields, the antenna behavior can be controlled and a dual band frequency was introduced. The local regions with micro-scale inclusions showed good agreement with a homogeneous substrate section with the same predicted permittivity. These heterogeneous substrates can be potentially created using nanomaterials