P. Waldow

MIM CRLH Series Mode Zeroth Order Resonant Antenna (ZORA) implemented in LTCC Technology

A metal-insulator-metal (MIM) composite right/left- handed (CRLH) series mode zeroth order resonant antenna (ZORA) implemented in LTCC technology is presented and demonstrated to exhibit excellent efficiency (71%) and co-to-cross polarization performances, in addition to a high gain (10 dB) provided by its large electrical size of 2 lambda0. Due to its versatile characteristics, high performances and capability to attain at low cost high directivities, conventionally available only with standard arrays, this antenna may find various applications in future.

Composite right/left-handed /spl lambda/-resonator ring antenna for dual-frequency operation

A novel ring structure operating as a dual-frequency resonating antenna is presented. The ring analysis and design is based on the concept of the composite right/left-handed transmission line (CRLH TL), with the particularity that the ends of the line are connected together so as to form a closed loop. As in the case of conventional ring resonators, multiples of full wavelength (n/spl lambda/) field distributions are supported. The key feature of the proposed resonator is that an identical field distribution along the ring is achieved at two different operating frequencies. This phenomenon is due to the dual nature of the CRLH dispersion characteristic. The lower operating frequency corresponds to the /spl lambda/ mode in the left-handed (LH, backward wave, /spl beta/<0) range, while the higher resonance frequency corresponds to the /spl lambda/ mode in the right-handed (RH, forward wave, /spl beta/>0) range. The main benefit of having the same field distribution is that identical performances (radiation, polarization and matching) are achieved at each of the two frequencies. The proposed antenna structure has been simulated with commercial MoM/FEM tools and validated with measurements on fabricated prototypes.

Enlarged half-wavelength resonator antenna with enhanced gain

A concept of gain enhancement by radiation aperture enlargement has been presented. The nonlinear dispersion relation of a CRLH TL has been used to enlarge the antenna length keeping the resonance frequency nearly constant. It has been shown that the gain is strongly dependent on the size of the radiation aperture. This fact supports the idea that the x-component of the electric field in the interdigital capacitors of the unit cells is the main contribution to the radiation aperture and is also in agreement with the far-field polarization. A maximum gain of 10.7 has been reached for the largest antenna with 18 unit cells.

Dual mode zeroth order ring resonator with tuning capability and selective mode excitation

A novel ring configuration supporting two orthogonal unique zeroth order modes is presented. The analysis and the design of this ring are based on the artificially engineered composite right left handed (CRLH) transmission lines. A CRLH transmission line exhibits unusual and more diverse propagation characteristics. In the dispersion diagram a lower left hand (LH) and a higher right hand (RH) frequency range is separated by a propagation band gap. This band gap is confined by two zero phase origins (/spl beta/=0), associated with an infinite guided wavelength at non-zero frequencies. Using the CRLH-TL in a ring configuration with connected ends, both zero phase origins along with their corresponding frequencies form a valid resonance mode. One zeroth order mode comes with a constant transmission line voltage, a so-called voltage mode, while the transmission line current is zero. The other zeroth order mode is referred to as current mode and operates at resonance with a constant transmission line current and zero voltage along the resonator line. A simple tuning technique for the voltage modes resonance frequency is addressed. Different feeding strategies to excite both zeroth order modes simultaneously in a one port device as well as decoupled two port selective mode feeding (either voltage or current mode) are discussed.

Tri-band and dual-polarized antenna based on composite right/left-handed transmission line

Relaxing the composite right/left-handed (CRLH) balance condition enables arbitrary tri-band CRLH resonant devices. This paper presents a tri-band and dual-polarized antenna based on this principle. The proposed CRLH antenna operates in the transversally-polarized zeroth order (ZO) shunt mode (n = 0) and in the two longitudinally-polarized half-wavelength (HW) modes (n = plusmn1). Explicit synthesis formulas are given for the CRLH tri-band operation. A specific microstrip design using MIM (metal-insulator-metal) series capacitors and shunt stub inductors is demonstrated. In this design, the three resonant modes n = -1, n = 0 and n = +1 exhibited similar input impedances (allowing a simple feeding structure), radiation patterns and efficiencies/gains.

Ultra-Compact Power Splitter Based on Coupled Surface Plasmons

A novel power splitter based on coupled surface plasmons (SPs) is proposed for optical frequency applications. This power divider is an ultra-compact forward or co-directional coupling device. A specific SiO2-Ag-SiO2 685-THz design is demonstrated by full-wave analysis, where a coupling length of only 36 nm and an overall dimension of around 500 nm is achieved. The underlying principle of coupled SPs may lead to various novel nanoscale optical devices.

The Representation of Derivative Operators in Yee's Staggered Grid in Bases of Compactly Supported Daubechies Wavelets

During our work on adaptive algorithms for FDTD we derived an effective technique to calculate coefficients for a wavelet-based higher-order derivative approximation in Yees staggered grid. Other researchers have evaluated the coefficients numerically, either directly [1] or after a Fourier Transform [2]. We describe a technique based on the Two Scale Relation (TSR) of scaling functions that yields the exact values for the stencils. In the end of the paper, we present an application (anisotropic uniaxial PML formulated by Gedney) of the coefficients.