Space-Filling Curve RFID Tags

A completely passive Radio Frequency Tag is proposed, utilizing the scattering from electrically small but resonant inclusions. When placing these space-filling curve inclusions in an array and scaling each element within the array such that each element has its own separate resonant frequency, a radio frequency barcode can be developed from the Radar Cross Section of the array. The narrow bandwidth inherent to such inclusions can be helpful in packing the overall signature into a relatively small frequency spectrum. Such Radio Frequency Tags may have potential use in some applications of Radio Frequency Identification Systems

High Impedance Metamaterial Surfaces Using Hilbert-Curve Inclusions

A metamaterial surface, composed of a periodic arrangement of Hilbert Curve inclusions above a conducting ground plane, is analyzed numerically and is shown to possess the properties of a high impedance surface by investigating the phase and magnitude of the reflection coefficient, Γ, for a plane wave of normal incidence. A parametric study is presented with respect to the iteration order of the Hilbert curve, the surface height above the ground plane, and the separation distance between the neighboring Hilbert elements within the surface array

Peano Antennas

In this letter, we investigate the radiation characteristics of Peano antenna, i.e., a single antenna made of a thin wire, patterned after a special type of space-filling curve known as the Peano curve. We use a moment-method-based simulation code to study various properties of this antenna, namely, the radiation pattern, impedance bandwidth, current distribution, cross-polarization level, radiation efficiency, and the feed location for achieving an electrically small matched antenna. As in the case of the Hilbert antenna, the radiation patterns of a Peano antenna resemble those of a linear dipole; however, this antenna has a lower cross-polarization level than the Hilbert antenna and, for a matched Peano antenna, the resonant frequency is lower than the same order matched Hilbert antenna at the expense of a smaller input-impedance bandwidth

Radiation Characteristics of Microstrip Dipole Antennas over a High-Impedance Metamaterial Surface made of Hilbert Inclusions

We analyze numerically the radiation characteristics of center-fed microstrip short dipoles and half-wave dipoles near a high-impedance surface made of Hilbert shape flat inclusions. We study the input impedance, pattern and gain of such radiating structures. We show that the radiation resistance of a microstrip dipole increases noticeably at certain frequencies near the resonant frequency of the Hilbert surface. Moreover, antenna gain enhancement at certain frequencies is observed for all dipole sizes we have analyzed

Bandwidth, Cross-Polarization, and Feed-Point Characteristics of Matched Hilbert Antennas

In this work, we have applied a moment-method-based simulation code to perform a detailed parametric study of the bandwidth, cross-polarization level, and the feed location characteristics of the matched Hilbert antenna. It is shown that a properly chosen off-center near-the-end feed point may provide an approximate 50-Ω real input impedance at the fundamental resonant frequency. The role of different iteration order for Hilbert antennas, approximately matched to 50-Ω line, on the bandwidth and cross-polarization level of such antennas are investigated numerically. As was shown by Vinoy et al. the radiation patterns resemble those of a linear dipole and for a fixed-area-matched Hilbert antenna, the resonant frequency can be lowered by increasing the iteration order n. However, for such matched antennas, the bandwidth for VSWR \u3c 2 will be decreased and the cross-polarization level may be different for the higher iteration-order antennas

Peano High Impedance Surfaces

Following our previous work on metamaterial high-impedance surfaces made of Hilbert curve inclusions, here we theoretically explore the performance of the high-impedance surfaces made of another form of space-filling curve known as the Peano curve. This metamaterial surface, formed by a 2-D periodic arrangement of Peano curve inclusions, is located above a conducting ground plane and is shown to exhibit a high surface impedance surface at certain specific frequencies. Our numerical study reveals the effect of the iteration order of the Peano curve, the surface height above the conducting ground plane and the separation distance between adjacent inclusions.Comment: 16 pages, 9 figures, submitted to Radio Scienc

Adaptive Polarization-Difference Imaging Algorithms for Through-the-Wall Microwave Imaging Scenarios

The preliminary results of application of Adaptive Polarization-Imaging Algorithm for Through-the-Wall Microwave Imaging problems are presented. Use of complete polarization information in the scattered field from the object together with the adaptation technique provides enhancement in detection of target movement