M. Drissi

An Innovative and Low Complexity PAPR Reduction Technique for Multicarrier Systems

Large peak to average power ratio (PAPR) is a common drawback of multicarrier signals. In wireless communication systems, dealing with high PAPR requires keeping an important margin from the power amplifier compression point. High power amplifier back-off leads to low power efficiency which is not suitable in many embedded systems. In this paper, a new iterative technique to reduce the PAPR of multicarrier signals is presented. The proposed technique called one-tone one-peak (OTOP) is based on the tone reservation principles. It has the advantage to be very easy to implement and to give an appreciable PAPR reduction while giving a full control over the reserved tones magnitude

Numerical simulation of a virtual matched load for the characterization of planar discontinuities

A mixed technique, based on the association of the integral equations solved by the method of moments to the theory of loaded scatterers, is shown to be useful for simulating planar discontinuities. The theory of loaded scatterers is used to include the effects of either localized or distributed loads through which the matching can be achieved. When using this technique for shielded discontinuities, the scattering parameters are obtained from the knowledge of only current or electric field maxima, and the errors associated with the accurate determination of the current or the electric field minimum evaluation encountered in other techniques are avoided.<<ETX>>

Packaging and interconnection mutual coupling effects in planar structures and discontinuities

An integral equation technique that is solved by the method of moments is used to analyze parasitic coupling in general shielded planar structures. The coupling between a planar component and its enclosure and the coupling between planar component themselves are studied. The first effect is illustrated by the calculated values of the effective permittivity of uniform planar lines and the S-parameters for a suspended stripline stub discontinuity for different enclosure geometries. The mutual coupling between two small spaced microstrip stubs is also discussed. Comparison with other numerical results as well as with published experimental ones has verified the accuracy and the numerical efficiency of the present approach.<<ETX>>

A rigorous analysis of novel microstrip circular patch antennas

Planar antennas are widely used as radiating elements in large arrays. The commonly used microstrip shapes are rectangular and circular patches. The microstrip circular patch (MCP) requires less area compared to the rectangular one. However, the edge-fed circular patch antenna presents a high return loss which restricts the use of a 50/spl Omega/ microstrip transmission line as a feed. In the present work, an inserted coplanar feed line for matching the MCP antenna to 50/spl Omega/ impedance is developed. The analysis is based on the resolution of the electric field integral equations (EFIE) by the method of moments (MoM) where triangular subdomain discretization is used to handle the arbitrary shape of the radiating elements. Two new MCP antennas which improve the matching performances at the resonance frequencies of the TM/sub 11/ and TM/sub 12/ modes are discussed.<<ETX>>

Theoretical and experimental investigation of some general suspended stripline discontinuities

An integral equations technique associated with a 2-D moment method is used to characterize some general suspended stripline discontinuities, i.e., a stub, a meander, a bend, and a bent-stub, for which two components for strip surface current are taken into consideration. A numerical simulation of a matched load at terminations of the discontinuities is achieved and is used for a precise determination of scattering matrix parameters for these discontinuities. Good agreement is achieved between numerical results and experimental ones that are obtained using the de-embedding calibration technique. The effect of parasitic waveguide modes is discussed.<<ETX>>

Compact active antenna for mobile devices supporting 4G LTE

The advent of 4G LTE has ushered in a growing demand for embedded antennas that can cover a wide range of frequency bands from 698 MHz to 2.69 GHz. A novel active antenna design is presented in this paper that is capable of covering a wide range of LTE bands while being constrained to a 1.8 cm3 volume. The antenna structure utilizes Ethertronics EtherChip 2.0 to add tunability to the antenna structure. The paper details the motivation behind developing the antenna and further discusses the fabrication of the active antenna architecture on an evaluation board and presents the measured results.

Dispersion Characteristics Analysis of Multilayer Microstrip Lines with Finite Ground Plane

A full-wave analysis of microstrip with a finite ground plane is developed using the Greens functions of a multilayer geometry not backed by a ground plane. A two-dimensional Method of Moment (MoM) is used to derive the current distribution on each metallization including the finite ground plane. The calculated dispersion characteristics for coplanar strips are compared to the available experimental data where good a agreement is obtained. Then, the effect of the finite ground plane on the microstrip propagation characteristics is rigorously analysed. Finally, some experimental measurements of microstrip resonator with a limited ground plane are achieved and compared with the theoretical results.

Broadband lens antenna for wireless communications

A broadband waveguide-fed slot antenna is firstly presented. This antenna is then associated with a focusing structure (dielectric lens) in order to improve the performance in the K band. A low cost and broadband antenna with 18 dBi measured gain is obtained and is therefore suitable to many commercial millimeter-wave systems.

A full wave analysis of active planar circuits including non-linear loads

In this paper a rigorous electromagnetic analysis of active planar circuits operating as non-linear microwave components is proposed. The approach is based on the association of the integral equation technique with the harmonic balance one. The formulation includes non-linear devices as additional time domain boundary conditions which are achieved through the modification of the excitation vector and the generalised impedance matrix in the method of moments. The obtained numerical results of active microstrip structures are compared to those achieved with a standard equivalent circuit approach and the observed differences are discussed.

A full-wave analysis of active uniplanar structures

The coplanar waveguide (CPW) is well suited to feed printed antenna thanks to its interesting properties (less radiation, easy component insertion). The ability to insert an amplifier on a CPW-fed slot antenna to increase the bandwidth has been investigated experimentally in terms of the transfer power gain. A full-wave analysis of active uniplanar structures is proposed by combining the loaded scatterers theory, and the integral equation technique. The developed theory is applied to optimize an amplifier on a CPW and an active CPW-fed slot antenna. The results obtained are compared to an equivalent circuit approach and the observed differences are discussed.