Abdelwahed Tribak

Octave Bandwidth Compact Turnstile-Based Orthomode Transducer

A 64% instantaneous bandwidth scalable turnstile-based orthomode transducer to be used in the so-called extended C-band satellite link is presented. The proposed structure overcomes the current practical bandwidth limitations by adding a single-step widening at the junction of the four output rectangular waveguides. This judicious modification, together with the use of reduced-height waveguides and E-plane bends and power combiners, enables to approach the theoretical structure bandwidth limit with a simple, scalable and compact design. The presented orthomode transducer architecture exhibits a return loss better than 25 dB, an isolation between rectangular ports better than 50 dB and a transmission loss less than 0.04 dB in the 3.6-7 GHz range, which represents state-of-the-art achievement in terms of bandwidth.

Broadband 4×4 Butler matrix using wideband 90° hybrid couplers and crossovers for beamforming networks

The design and simulation of a wideband four-port steerable beamforming networks using a 4×4 Butler matrix for the 2.4 GHz applications is presented. The aim of this work is to develop an antenna array feeding network based on Butler matrix with a large bandwidth in order to cover the IEEE 802.11b/g/n band. In order to achieve wideband features, the matrix uses two-section branch-line couplers and four-section branch-line crossovers instead of the standard ones. The proposed circuit exhibits a high isolation and wideband 4×4 Butler matrix designed and simulated by using a single-layer FR-4 substrate, which covers the frequency band ranging from 2.1 GHz to 2.75 GHz. The return losses and the isolation are better than 28 dB and 30 dB, respectively, with its good performance is more suitable for IEEE 802.11b/g/n and ISM applications.

A Compact CPW-Fed Planar Pentagon Antenna for UWB Applications

In this paper, the design and analysis of a compact coplanar waveguide-fed ultra wideband pentagon antenna are presented. To achieve ultra wideband performance, two modiflcations are introduced. The flrst one is to remove a small fan angle on each side of the ground plan, and the second one is to modify the sharp of the patch in the width. The optimal dimensions can be achieved by a parametric analysis. The antenna design exhibits a very wide operating bandwidth of 16.7GHz with a return loss better than 10dB in the frequency range from 4.46GHz to 21.14GHz. The gain of the proposed antenna is 6.3dBi. This antenna conflguration will be useful for UWB indoor application as it is easy to fabricate and integrate with RF circuitry. All simulations in this work were carried out by using the electromagnetic software CST.

Circular polarized square patch antenna array for wireless power transmission

Wireless power transmission is a process that takes place in any system where electrical energy is transmitted from a power source to an electrical load without a wired connection. Wireless transmission is ideal in cases where instantaneous or continuous energy transfer is needed, but interconnecting wires are inconvenient, hazardous, or impossible. Antenna has become the most vital element in any RF system due to its capability as a radio wave transceiver. A properly designed antenna is desirable to ensure efficient transfer of energy. This paper proposes a square patch antenna array 3×3 designed with a circular polarization using slots for wireless power transmission, through radio wave frequency of 2.45GHz. The array is being designed and simulated by using CST microwave software.

CPW and microstrip line-fed compact fractal antenna for UWB-RFID applications

In this study, we present an implementation of Ultra Wide Band (UWB) Koch Snowflake antenna for Radio Frequency Identification (RFID) applications. The compact antenna, based on the Koch Snowflake shape, is fed by coplanar waveguide (CPW) and by microstrip line with an overall size of 31 × 27 × 1. 6m m 3 . The simulation analysis is performed by CST Microwave Studio and compared with HFSS software. The antenna design exhibits a very wide operating bandwidth of 13 GHz (3.4- 16.4 GHz) and 11 GHz (3.5-14.577 GHz) with return loss better than 10 dB for microstrip line antenna and CPW antenna respectively. A prototype of CPW and microstrip antenna was fabricated on an FR4 substrate and measured. Simulated and measured results are in close agreement. The small size of the antenna and the obtained results show that the proposed antenna is an excellent candidate for UWB-RFID localization system applications.

Ku-band waveguide band-pass filter with iris radius

This paper presents the design, simulation, and implementation of band pass filters in rectangular waveguides with radius, having 0.1 dB pass band ripple and 6.3% ripple at the center frequency of 14.2 GHz. A Mician microwave wizard software based on the Mode Matching Method (MMM) was used to simulate the structure of the filter. Simulation results are in good agreement with the measured one which improve the validity of the waveguide band pass filter design method.

A New Microstrip Diplexer Using Open-Loop Resonators

In this paper, a new microstrip diplexer using open loop resonators with compact size and high isolation is designed and fabricated for the WLANs (IEEE 802.11b/g at 2.4 GHz and IEEE 802.11a at 5.2 GHz) applications. The diplexer is formed by two dual-mode band pass filters (BPFs) using an asymmetric fork-form feed line and two open loop resonators. The diplexer has less than 3 dB insertion loss and the isolation between the two channels is more than 25 dB. Furthermore, the proposed diplexer shows several transmission zeros beside the pass bands which improves the selectivity of the BPFs and thus improves the isolation between lower and upper channel filters and achieves a significant attenuation of the undesired harmonics. The electrical performances of the diplexer are investigated numerically by using Momentum integrated in ADS Agilent and CST microwave software. Good agreement between the simulation and measurement results is achieved.

ULTRA-BROADBAND HIGH EFFICIENCY MODE CON- VERTER

In this paper, we develop a small-sized mode converter with high performance, high conversion e-ciency and instantaneous bandwidth as high as 55%. This mode converter transforms energy from the TM01 flrst high-order mode towards the fundamental TE11 circular waveguide mode The proposed structure increases the free spurious operating bandwidth in comparison with the existing results in literature. An X/Ku-bands experiment prototype unit was designed, ensuring practical return losses better than 28dB and insertion losses less than 0.1dB (conversion e-ciency > 98:8%) within the entire frequency bandwidth ranging from 9.25GHz to 16.25GHz The presented architecture ofiers useful features such as very wide bandwidth, small size, easy achievement as well as excellent performance, which makes it very suitable for High-power microwave (HPM) sources that generate the TM01 circular waveguide mode. In these cases, the TE11 mode is needed since it has a convergent radiation pattern able to drive conventional antennas. Moreover, this compact concept is fully scalable to any millimeter frequency band.

Reconfigurable and Tunable Filtenna for Cognitive LTE Femtocell Base Stations

A single-port uniplanar antenna with a built-in tunable filter is presented for operation in multiple LTE bands for cognitive femtocell applications. The antenna is based on a monopole microstrip patch fed by coplanar waveguide. The frequency reconfigurability is achieved by using two PIN diodes to couple or decouple a ring slot resonator filter from the antenna feed line. By switching the PIN diodes, the proposed design can operate in either wideband or narrowband modes. When the antenna operates in the narrowband state, two varactor diodes are used to continuously tune the narrowband frequency from 2.55 to 3.2 GHz, while the wideband state is obtained over the 1.35–6.2 GHz band. The diodes and their biasing networks have nearly no severe effect on the antenna characteristics. Prototypes of the proposed structure using ideal and real switches, with and without varactors, are fabricated and tested. Measured and simulated results are in good agreement, thus verifying the good performance of the proposed design. The obtained results show that the proposed antenna is very suitable for cognitive radio applications, in which the wideband mode is used for spectrum sensing and the narrowband mode for transmission at different frequency bands.

A novel design of elliptic fractal multiband planar antenna for wireless applications

The mobile phone applications had known an increase through the last years. Starting with GSM-900 on 1992, a mobile phone can today support the quad bands (850, 900, 1800 and 1900 MHz), Bluetooth, IMT-2000 (International Mobile Telecommunications), Wi-Fi (2.4 and 5 GHz), GPS, LTE (Long Term Evolution), ISM (Industrial, Scientific & Medical) bands (2.4 and 5.8 GHz) and NFC (Near Field Communication). These developments need antennas with a multiband behavior, small size and low cost of fabrication.