A truncated conical dielectric resonator antenna for body-area network applications

Copyright © 2009 IEEEAn inverted truncated annular conical dielectric resonator antenna (DRA) for potential use in body-area network (BAN) applications is introduced. The antenna is designed to operate within the lower European ultrawideband (UWB) frequency band (3.4–5.0 GHz). The selected DRA geometry in combination with a capacitively loaded monopole as the feeding mechanism results in a low-profile antenna with wide bandwidth and stable monopole-like patterns. In addition, the antenna exhibits good UWB properties, as characterized through the dispersion effect on the transmitted impulse voltage signal. The DRA has been numerically and experimentally examined for both free-space and on-body applications, demonstrating a good performance in the frequency- and time-domain.Georgios Almpanis, Christophe Fumeaux, Jürg Fröhlich and Rüdiger Vahldieckhttp://ieeexplore.ieee.org/xpl/preabsprintf.jsp?arnumber=461095

Wavelength Tunable Antenna Coupled Infrared Detectors

A tuned antenna-coupled infrared detector is made possible by application of a bias voltage in the range of a few hundred millivolts. The use of first and second antenna arms connected to the detector makes possible polarization tuning which eliminates the need for bulk-optical polarization filters. An alternative tuned detector is one in which the antenna is frequency tuned by a capacitative device to make the detector particularly responsive to 8 um to 12 um infrared radiation. When integrated into focal plane arrays, these detectors can be used in remote-sensing systems to facilitate enhanced image recognition, feature extraction and image-clutter removal. One preferred version of the polarization tuned antenna has longitudinal metal antenna arms extending outward from an infrared(IR) sensor in a spiral pattern, with polarization tuning devices connected between the antenna arms, and a voltage for controlling the polarization tuning devices, wherein the polarization tuning devices

Metamaterial-inspired multichannel thin-film sensor

A multichannel thin-film sensor is implemented from a set of microstrip-coupled split-ring resonators (SRR's) with different dimensions. Each SRR exhibits a unique high-Q resonance that is sensitive to the presence of a sample in a particular area. Hence, this SRR-based sensor can function (i) to detect different samples simultaneously to increase the throughput or (ii) to characterise nominally identical samples at multiple frequencies to increase the sensor selectivity. The design principle is validated with simulation and measurement. Owing to the optimized design, sensing a low-permittivity film with a thickness as small as one thousandth of the operating wavelength is achievable.Comment: 7 pages, 4 figure

Directional excitation of surface plasmons by dielectric resonators

An important aim of current research on plasmonics is to develop compact components to manipulate surface plasmon polaritons (SPPs) and specifically to develop efficient SPP couplers. The commonly used metallic resonators are inefficient to couple free-space waves to SPPs and metallic gratings require oblique incidence for achieving unidirectional propagation. In this article, we propose to use nanoscale nonuniform arrays of dielectric resonator antennas (DRAs) to realize unidirectional launching of SPPs. DRAs are made of low-loss high-permittivity nanostructures operating on a metal surface. The applications of metallodielectric nanostructures can produce resonances mainly in the low-loss dielectric parts and hence the power dissipated through oscillating current in metal can be reduced. Similar to metallic resonators, DRAs operating near resonance can provide phase control when coupling incident waves into SPPs, adding degrees of freedom in controlling propagation direction. The theoretical analysis in this article, with numerical validation, shows efficient SPPs launching by nonuniform array of cylindrical DRAs into a predesigned direction. Furthermore, with proper patterning, optimal launching can be achieved by avoiding power leakage via deflection into free space. The SPP launching condition and the influence of propagation loss are also mathematically analyzed from the viewpoint of antenna array theory. The SPPs launchers based on DRAs have a potential for applications in highly efficient integrated optics and optical waveguides.C. Fumeaux acknowledges the Australian Research Council (ARC) Future Fellowship funding scheme for support under Grant No. FT100100585

Sub-diffraction thin-film sensing with planar terahertz metamaterials

Planar metamaterials have been recently proposed for thin dielectric film sensing in the terahertz frequency range. Although the thickness of the dielectric film can be very small compared with the wavelength, the required area of sensed material is still determined by the diffraction-limited spot size of the terahertz beam excitation. In this article, terahertz near-field sensing is utilized to reduce the spot size. By positioning the metamaterial sensing platform close to the sub-diffraction terahertz source, the number of excited resonators, and hence minimal film area, are significantly reduced. As an additional advantage, a reduction in the number of excited resonators decreases the inter-cell coupling strength, and consequently the resonance Q factor is remarkably increased. The experimental results show that the resonance Q factor is improved by 113%. Moreover, for a film with a thickness of \lambda/375 the minimal area can be as small as 0.2\lambda by 0.2\lambda. The success of this work provides a platform for future metamaterial-based sensors for biomolecular detection.Comment: 8 pages, 6 figure

Area Receiver with Antenna Coupled Infrared Sensors

A small array of antenna-coupled infrared bolometer detectors is connected in parallel. This small array is suitable as an individual area-receiving pixel of an infrared focal plane array. These pixels will have better coupling efficiency to extended sources than are possible with individual antenna-coupled sensors, which have a spatial response on the order of one wavelength in dimension. This pixel can be used to provide the advantages of antenna-coupled IR sensors (e.g., fast response, wavelength tuning, and polarization tuning) while increasing the collection efficiency of the sensors to non-laser sources. When integrated into focal plane arrays, these detectors can be used in remote-sensing systems to facilitate enhanced image recognition, feature extraction and image-clutter removal. A preferred version of the pixel forming the focal plane array antenna has a plurality of two parallel longitudinal metal antenna arms extending outward and opposite from an infrared (IR) bolometer

Manifestation of the coupling phase in microwave cavity magnonics

The interaction between microwave photons and magnons is well understood and originates from the Zeeman coupling between spins and a magnetic field. Interestingly, the magnon/photon interaction is accompanied by a phase factor which can usually be neglected. However, under the rotating wave approximation, if two magnon modes simultaneously couple with two cavity resonances, this phase cannot be ignored as it changes the physics of the system. We consider two such systems, each differing by the sign of one of the magnon/photon coupling strengths. This simple difference, originating from the various coupling phases in the system, is shown to preserve, or destroy, two potential applications of hybrid photon/magnon systems, namely dark mode memories and cavity-mediated coupling. The observable consequences of the coupling phase in this system is akin to the manifestation of a discrete Pancharatnam-Berry phase, which may be useful for quantum information processing

Compact electric-LC resonators for metamaterials

Alternative designs to an electric-LC (ELC) resonator, which is a type of metamaterial inclusion, are presented in this article. Fitting the resonator with an interdigital capacitor (IDC) helps to increase the total capacitance of the structure. In effect, its resonance frequency is shifted downwards. This implies a decreased overall resonator size with respect to its operating wavelength. As a result, the metamaterial, composed of an array of IDC-loaded ELC resonators with their collective electromagnetic response, possesses improved homogeneity and hence is less influenced by diffraction effects of individual cells. The impact of incorporating an IDC into ELC resonators in terms of the electrical size at resonance and other relevant properties are investigated through both simulation and experiment.Comment: 5 pages, 5 figure