Lassaad Latrach

Development of a novel wideband conical Dielectric Resonator Antenna

In this paper, we propose a dual layer conical Dielectric Resonator Antenna (DRA) excited by a slot. The inclination of the two environments with different dielectric constants relative to the slot can create a Circular Polarization (CP). Simulations performed under Ansoft HFSS software show that the proposed conical shaped DRA is circularly polarized and can reach a large bandwidth of 1.14 GHz with a gain of about 6.4 dB at the frequency of 5.8 GHz.

Improvement RFID antenna by using nested split ring resonators

This paper focuses in the first part to demonstrate the correlation between the physical quantities of nested split ring resonators and its frequency characteristics. The investigation is conducted in a parametric study based on the simulation results and the theoretical proofs. The second part is reserved for our proposed approach to develop the method of improvement and miniaturization of RFID antennas by the inclusion of metamaterials. All simulation results were made by the CST Microwave Studio.

RFID antenna by using metamaterials with negative effective permeability

In this article, we propose a new approach to study a suitable structure of metamaterial antennas for RFID technology that operates in the UHF band. This antenna is constituted by a dipole associated to a network specific and homogeneous structure composite of circular split ring resonators that can produce a negative permeability. Thanks to the effect of effective negative permeability, we can improve the performance and reduce the size of the studied antenna, which is very important for the RFID applications. The parameters considered in this paper are the resonant frequency, return loss, frequency band, radiation pattern, gain and directivity of antenna. All results of the simulations were done by CST Microwave Studio simulation software.

Analysis of planar microwave structures using transmission line-periodic lumped circuit by an iterative method WCIP

The theory of a novel approach of the WCIP method to analyze periodic lumped circuits has been presented. Transmission lines in their planar form (microstrip technology) can be modelled by an equivalent periodic lumped circuit that permits a fast analysis instead of the use of many electromagnetic full wave simulators which require a great running time and great memory size. The validation of the proposed approach was made by comparing the results of simulation with ADS simulator of a bandpass filter designed in its planar form and equivalent periodic lumped circuit.

Analyzing of one dimensional quasi periodic circuit by using auxiliary sources in a WCIP method

A new approach of the iterative method WCIP (Wave Concept Iterative Process) using the technique of the auxiliary sources considers a pixel or a unit cell in a periodic structure as an electrical circuit instead of a sub-domain representing metal or dielectric in the classical iterative method. The intersection of this new approach with the old is on the application of the iterative process in waves between the space and spectral domains in order to calculate the electric field and the density of current. The novel approach is introduced by the study of two types of defects on an uniform transmission line. The first one is a defect of a resistance, the other is a defect of a reactance. The results of simulation of the variation of current along the transmission line are agree with the theory which validates our proposed approach.

Enhancement of bandwidth and gain of a multilayer circularly polarized DRA

In this paper, a multilayer conical dielectric resonator antenna (DRA) excited by two coaxial cables has been investigated. The phase shift of the two coaxial cables with 90° creates a circular polarization of the radiated electromagnetic wave. The proposed structure provides a bandwidth of about 41% with a gain ranging from 4.8 dB to 8.7 dB in the bandwidth. The simulation study of the proposed antenna is carried out using Ansofts HFSS software and the parametric study has been made by adding a layer with different permittivity. The number of layers and the arrangement of permittivities are also studied.

Effect of Complementary Split Ring Resonator Structure on PIFA Antenna

This paper proposes a new design of Planar Inverted-F Antenna with complementary split ring resonators (CSRRs). The operating frequency of this antenna is 2.425 GHz for Wireless Local Area Network (WLAN) application. The method is to incorporate a single CSRR cell and a periodic array CSRRs on the radiating patch. We studied the effect of this method on the characteristics of antenna in free space and in the presence of the user. We used a homogeneous model of a human head near our antenna. The parameters that considered in these works are gain, electric field, magnetic field, return loss, radiation pattern, power loss density and Specific Absorption Rate. The addition of CSRRs on to PIFA antenna will improve the gain from 4.76 dB to 4.81 dB and will reduce the Specific Absorption Rate from 3.57 W/kg to 2.95 W/kg.

A Novel Cylindrical DRA for C-Band Applications

In this paper, we study a Dielectric Resonator Antenna of cylindrical shape with circular polarization for applications in the C band. The proposed antenna is composed of two different layers. The first is Polyflon Polyguide with relative permittivity er1 = 2.32 and a loss tangent tand = 0.002 as a lower layer. The second is Rogers RO3010 with relative permittivity er2 = 10.2 and a loss tangent tand = 0.0035 as an upper layer which is excited by dual probe feed. The 90° phase shift of two probes feed can create a circular polarization. In this study, we focused on the effect of the variations in the height of the Polyflon Polyguide as well as the probe feed. Simulations under HFSS software have led to bandwidth values of about 2.2 GHz and 2.6 GHz for the proposed antenna with one probe and dual probe, respectively. The obtained gains are higher than 5.4 dB and can range up 8.1 dB.

RFID patch antenna by using complementary split ring resonator oriented at 45 degrees

This paper is specialized to highlight the method of miniaturization and improvement the patch antenna by using the complementary metamaterial. This method is shown by two structures composed of a patch antenna integrated on its upper surface a cell of a complementary split ring resonator for the first technique. In the second structure, we replace the unit cell with a homogeneous and periodic array contain the elements of complementary split ring resonators. The magnetic resonator is placed at the middle of the radiating patch in parallel with the transmission line and with an orientation angle is fixed to 45 degrees. These two techniques widespread at the traceability applications by wireless communication for RFID technology at the operation frequency 2.45GHz. The objective is to first verify the effect of inclusion the complementary metamaterials with a patch antenna and then show the efficiency and advantage to orient the complementary split ring resonator at an angle 45 degrees. Finally, a comparison made on the two structures in order to propose the perfect technique. All simulation results were made by the CST Microwave Studio.

Electrical modeling of split ring resonators operating in the UHF band

The article in hand deals present a new approach focuses on the electric modelling of split ring resonators based on an equivalent circuit. The elements of circuit are determined from geometric parameters forming the three dimensional model of this type of resonators. Firstly an analytic study is proposed about the determination of the components of the circuit in function the physical parameters with a review about comparison between obtained results when the simulation of two different models is presented. Secondly, a demonstrative study on the effect of varying the value of the relative permittivity and determination the error rate at level the resonant frequency in the two models. The objective is to put the conditions and constraints necessary to make our equivalent circuit most responded and most efficient with zero error. The results of simulations are confirmed with using the two commercials software HFSS and ADS.