L-shaped Resonator Research Articles

Dual-band filter design using L-shaped stepped impedance resonators

This study demonstrates the feasibility of using microstrip L-shaped stepped impedance resonators in a dual-band filter, in conjunction with one of two coupled fed structures. Traditional single-band coupled filter design theory is used and each design parameter of the filter is controlled by two suitable physical parameters. Thus, the specifications, such as the central frequencies and the bandwidth of the two bands, can be fulfilled simultaneously. The filter maintains the geometry of the resonators without the need for additional matching networks. Design curves are constructed systematically, and used to obtain an appropriate pair of physical parameters that meet the desired specifications without trial and error. The L-shaped resonator makes the required values of the physical parameters possible to be found. Two dual-band filters operated at 2.4/5.2 GHz bands are fabricated and measured to verify the design concept.

A Novel Band-Notched Planar Monopole Antenna for Ultrawideband Applications

In this letter, a novel planar monopole antenna with a variable frequency band-notch characteristic for ultrawideband (UWB) applications is presented. The UWB property is achieved by embedding two shorted rectangular quarter-wavelength resonators. Two other L-shaped quarter-wavelength resonators coupled to the radiating patch are also used in order to generate the frequency band-stop performance and control antenna characteristics such as band-notch frequency and its bandwidth. The designed antenna has a stopband of 5-5.9 GHz while maintaining wideband performance from 3.1 to 11 GHz with VSWR <; 2.

ULTRA-WIDEBAND SMALL SQUARE MONOPOLE ANTENNA WITH VARIABLE FREQUENCY BAND-NOTCH FUNCTION

In this paper, a novel printed monopole antenna for ultra wideband applications with variable frequency band-notch characteristic is presented. The proposed antenna consists of a stepped square radiating patch with modifled W-shaped slot and a ground plane with rectangular sleeve and pair of L-shaped resonator which provides a wide usable fractional bandwidth of more than 130% (3.05{14.3GHz). By cutting a modifled W-shaped slot with variable dimensions on the radiating patch frequency band-stop performance is generated and we can control its characteristics such as band-notch frequency and its bandwidth. The designed antenna has a small size of 12 £ 18mm 2 while showing the band rejection performance in the frequency band of 5.08 to 5.91GHz.

Negative refraction of a double L-shaped metamaterial

We investigate numerically and experimentally the negative refraction of left-handed metamaterials (LHMs) with L-shaped resonator inclusions. This single sided double L-shaped metamaterial simultaneously has an electric and magnetic response to an incident electromagnetic wave, and can exhibit left-handed properties in a frequency range with negative permittivity and negative permeability overlapped. The simulated and the experimental results verify the negative index of refraction of L-shaped LHMs. Then two magnetic resonant modes of the L-shaped resonator are discussed; the mechanism of the negative refraction of double L-shaped LHMs is due to both the exchange of conduction current interaction and magneto-inductive current interaction.

Double-Layered Quad-Band Bandpass Filter for Multi-Band Wireless Systems

A compact double-layered quad-band (DLQB) bandpass filter (BPF) is presented to provide four passbands at the desired frequencies with efficient out-of-band suppression. The designed filter is verified by pattern implementation on two FR4 boards. The proposed DLQB-BPF consists of two L-shaped resonators on the first layer and two symmetrically-coupled stepped-impedance resonators (SIRs) on the second layer. The bottom of the second layer is ground plane. There are seven transmission zeros generated to perform quad-band characteristics at 1.57 GHz, 2.45 GHz, 3.6 GHz, and 5.8 GHz. An equivalent circuit model is constructed by analyzing the symmetry property of the proposed filter. A good agreement between the simulated and measured results is observed.

Wideband L-Shaped Dielectric Resonator Antenna With a Conformal Inverted-Trapezoidal Patch Feed

In this paper, a new dielectric resonator antenna (DRA) is introduced for wideband applications, where a simple L-shaped dielectric resonator (DR) is excited by a conformal inverted-trapezoidal patch connected to a microstrip line. It is observed that the impedance bandwidth can be expanded by using an inserted intermediate substrate, an L-shaped DR, and an inverted-trapezoidal patch feed mechanism. The experimental and numerical results were carried out and compared, showing a good agreement. The measured results demonstrate that the proposed DRA achieves an impedance bandwidth of about 71.4% for VSWR les 2, covering the frequency range from 3.87 to 8.17 GHz. Furthermore, this antenna provides a stable broadside radiation pattern across the operating bandwidth.

High Rejection L-Resonator Notch Filter with Flexible Electromagnetic Coupling and Second Harmonic Suppression Using High Dielectric Overlays

The recent technique of electromagnetic (EM) coupling is used here for the microstrip notch filter. It employs the normal λg/2 L-shaped microstrip resonator as a transmission type rejection filter for 2.4 GHz with its λg/4 arm coupled electromagnetically to the 50 Ω transmission line exactly under it. The L-resonator and feed line are on two separate TMM4 (ϵr = 4.5) substrates. The well-known flexibility of EM coupling can be used in various ways, e.g., for coupling many resonators to a single line. In addition, to allow a wider and symmetric pass band, second-harmonic suppression has also been employed, using different dielectric overlays (TMM4 and Al2O3). The overlay thickness is adjusted to effectively equalize the even- and odd-mode phase velocities. The overlay of Al2O3 with ϵr higher than that of substrates is found to give better results. The experimental and simulation results are in good agreement.

Optical metamaterials at near and mid-IR range fabricated by nanoimprint lithography

Two types of optical metamaterials operating at near-IR and mid-IR frequencies, respectively, have been designed, fabricated by nanoimprint lithography (NIL), and characterized by laser spectroscopic ellipsometry. The structure for the near-IR range was a metal/dielectric/metal stack "fishnet" structure that demonstrated negative permittivity and permeability in the same frequency region and hence exhibited a negative refractive index at a wavelength near 1.7 um. In the mid-IR range, the metamaterial was an ordered array of four-fold symmetric L-shaped resonators (LSRs) that showed both a dipole plasmon resonance resulting in negative permittivity and a magnetic resonance with negative permeability near wavelengths of 3.7 um and 5.25 um, respectively. The optical properties of both metamaterials are in agreement with theoretical predictions. This work demonstrates the feasibility of designing various optical negative-index metamaterials and fabricating them using the nanoimprint lithography as a low-cost, high-throughput fabrication approach.

Analysis of NRD components via the order-reduced volume-integral-equation method combined with the tracking of the matrix eigenvalues

This paper presents a novel technique for the calculation of the proper modes of two- and three-dimensional nonradiating dielectric (NRD) components for millimeter-wave applications. The electromagnetic analysis is performed by the order-reduced volume-integral-equation method, which leads to a homogeneous matrix problem. The calculation of the dispersion diagram of NRD components and of the resonance frequencies of NRD resonators require the determination of the frequencies that correspond to nontrivial solutions of the matrix problem. Those frequencies are determined by the eigenvalue tracking (ET) method, which permits to follow the path of the matrix eigenvalues in the complex plane when varying the frequency. Compared to standard approaches (based on the direct search of the determinant zeros or on the singular value decomposition), the ET method requires a much smaller number of frequency points and, therefore, a much smaller number of electromagnetic analyses. The effectiveness of the proposed approach is demonstrated through the determination of the dispersion diagram of an NRD guide and the calculation of the resonance frequencies of an L-shaped resonator. The comparison with experimental data is also reported in the case of a rectangular NRD resonator

Broadband L-shaped dielectric resonator antenna

In this letter, a broadband inverted L-shaped dielectric resonator antenna (DRA) is proposed. The DRA with the two equiangular-triangle across sections is built on a ground plane and excited by a coaxial probe to provide broadside radiation patterns. The simulated and measured results verify that the proposed antenna offers a bandwidth of 38% (from 1.71 to 2.51 GHz) and stable broadside radiation patterns. The proposed antenna is suitable for multiband wireless communication applications as digital communication systems (DCS; 1710-1880 MHz), personal communication systems (PCS; 1850-1990 MHz), universal mobile telecommunication systems (UMTS; 1920-2170 MHz), and wireless local area networks (WLANs; 2.4-2.485 GHz).