RAFs associés à une ligne microruban de 50 Ω. from publication: Design of metamaterials for applications to microwave circuits and antennas | Structures based. Download scientific diagram | 1: Section de la ligne microruban blindée from publication: Caractérisation électromagnétique de composants et conception de . Download scientific diagram | le Circuit équivalent de l’alimentation par ligne microruban. from publication: ETUDE ET CONCEPTION D’ANTENNES ULTRA.
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Microstrip is a type of electrical transmission line which can be fabricated using printed circuit board technology, and is used to convey microwave mjcroruban signals.
It consists of a conducting strip separated from a mixroruban plane by a dielectric layer known as the substrate. Microwave components such as antennascouplersfilterspower dividers etc. Microstrip is thus much less expensive than traditional waveguide technology, as well as being far lighter and more compact.
Microrubam disadvantages of microstrip compared with waveguide are the generally lower power handling capacity, and higher losses. Also, unlike waveguide, microstrip is not enclosed, and is therefore susceptible to cross-talk and unintentional radiation.
However it is often found that the dielectric losses in FR4 are too high at microwave frequencies, and that the dielectric constant is not sufficiently tightly controlled.
For these reasons, an alumina substrate is commonly used. On a smaller scale, microstrip transmission lines are also built into monolithic microwave integrated circuits. Microstrip lines are also used in high-speed digital PCB designs, where signals need to be routed from one part of the assembly to another with minimal distortion, and avoiding high cross-talk and radiation.
Microstrip is one of many forms of planar transmission lineothers include stripline and coplanar oigneand it is possible to integrate all of these on the same substrate.
The electromagnetic wave carried by a microstrip line exists partly in the dielectric substrate, and partly in the air above it. In general, the dielectric constant of the substrate will be different and greater than that of the air, so that the wave is travelling in an inhomogeneous medium. In consequence, the propagation velocity is somewhere between the speed of radio waves in the substrate, and the speed ljgne radio waves in air.
This behaviour is commonly described by stating the effective dielectric constant or effective relative permittivity of the microstrip; this being the dielectric constant of an equivalent homogeneous medium i. A closed-form approximate expression for the quasi-static characteristic impedance of a microstrip line was developed by Wheeler: Curiously, Harold Wheeler disliked both the terms ‘microstrip’ and ‘characteristic impedance’, and avoided using them in his papers.
A number of other approximate formulae for the characteristic impedance have been advanced by other authors. However, most of these are applicable to only micrroruban limited range of aspect-ratios, or else cover the entire range piecewise.
In particular, the set of equations proposed by Hammerstad,  who modifies on Wheeler,   mivroruban perhaps the most often cited:. In order to build a complete circuit in microstrip, it is often necessary for the path of a strip to turn through a large angle.
One means of effecting a low-reflection bend, is to curve the path of the strip in an arc of radius at least 3 times the strip-width. To a first approximation, an abrupt un-mitred bend behaves as a shunt capacitance placed between the ground plane and the bend in the strip. Mitring the bend reduces the area of metallization, and so removes the excess capacitance. The percentage mitre is the cut-away fraction of the diagonal between the inner and outer corners of the un-mitred bend.
The optimum mitre for a wide range of microstrip geometries pigne been determined experimentally by Douville and James. The actual range of parameters for which Douville and James present evidence is 0.
Ligne microruban — Wikipédia
They report a VSWR of better than 1. For both the microfuban and mitred bends, the electrical length is somewhat shorter than the physical path-length of the strip. From Wikipedia, the free encyclopedia. Proceedings of the IRE. When possible, route high-speed differential pair signals on the top or bottom layer of the PCB with an adjacent GND layer.
TI does not recommend stripline routing of the high-speed differential signals.
In Sarkar, Tappan K. Wiley Series in Microwave and Optical Engineering. John Wiley and Sons. Retrieved from ” https: Microwave technology Planar transmission lines Printed circuit board manufacturing.