Nasreddine Ben Ahmed
 Write for Microwaves & RF
10 results found for Nasreddine Ben Ahmed, displaying items 1 - 10

July 2010   [Computer-Aided Engineering]
Form Microstrip Couplers With Shielded Membranes
Membrane-supported transmission lines and circuits are excellent candidates for millimeter-wave applications where conventional substrate-supported architectures begin to suffer from parasitic effects at the dielectric/ air interface.1-3 Transmission lines based on the technology, known as shielded-membrane-microstrip (SMM) transmission lines, have been used to realize an asymmetric tapered coupled-line coupler operating from 10 to 60...

May 2008   [Components]
Multilayer Microstrip Forms Tunable Bandstop Filters
Tunable bandstop filters are useful for a wide range of applications in eliminating unwanted signals and interference. Designing such filters can be greatly simplified with a new structure fabricated on multilayer microstrip substrates with a metallic diaphragm. This new structure overcomes the limitations of traditional tunable bandstop filter designs and supports simple, low-cost manufacturing processes.1 The new tunable filter...

March   [Components]
Analyze EM Parameters Of Slotted Tube Couplers
This numerical method accounts for thickness effects in determining the coupling coefficient as well as the even-and odd-mode impedances for slotted tube couplers. Abdelhafid Lallam Assistant Professor of Physics University of Mascara, BP 305 Route de Mamounia 29000 Mascara, Algeria; (045) 80-41-68/69, FAX: (045) 80-41-64, e-mail: ab_lallam@yahoo.fr Nadia Benabdallah Physics Engineer ...

November 2007   [Components]
Analyzing A Resonator For MRI Applications
Magnetic-resonance-imaging (MRI) systems can produce high-resolution images of cross sections of human bodies, proving to be invaluable for medical diagnostics. An important component in an MRI system is the RF probe used to emit a uniform RF magnetic field over the section of the human body under investigation and needed to receive the magnetic-resonance signals from the body for constructing high-quality images. What follows is an electromagnetic ...

July 2007   [Components]
Sliced Coaxial Cables Form Compact Couplers
Coupled sliced coaxial cables can provide signal coupling in a compact form factor for 50and 75-W systems. With the ready availability of accurate computer-aided-engineering (CAE) tools, it is possible to apply some basic formulas for calculating the dimensions of these structures to achieve a desired amount of coupling on different substrate materials. What follows is a straightforward approach to calculating those dimensions and analyzing coupler designs fabricated with coupled...

March 2007   [Components]
Design Coupled Microstrip Resonators For MRI
Magnetic-resonance-imaging (MRI) systems for medical and scientific applications require a high-performance, high-power inductor capable of establishing a uniformly strong magnetic field. The transverse-electromagnetic (TEM) resonator1 has received a great deal of attention recently as a superior replacement for standard birdcage coils2 in MRI applications requiring magnetic field levels of 4.7 to 9.4 T. For example, at operating frequencies of 200...

October 2006   [Components]
Design Directional Couplers For High-Power Applications
Directional couplers are invaluable components for measuring the power levels of signals in microwave systems. Especially when high power levels are involved, a properly designed directional coupler provides a lower-power coupled signal that is within the power measurement range of a power meter or spectrum analyzer. By applying the finite-element method (FEM) of analysis, it is possible to effectively analyze and design asymmetrical rectangular (coaxial-microstrip and coaxial-stripline)...

March 2006   [Components]
Analyzing EM Parameters For Shielded Bandline
Shielded symmetrical bandline transmission lines offer some noteworthy characteristics for high-frequency designs, including low signal loss. In order to better understand the nature of these transmission lines, they were examined using the finite-element method (FEM) 1,2 method-of-moments (MoM) analysis, 3 and curve-fitting techniques. Through these analysis approaches, a set of closed-form equations was developed to determine the characteristic...