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A TUNABLE STRIPLINE MEDIUM

IP.com Disclosure Number: IPCOM000008347D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-Jun-07
Document File: 1 page(s) / 60K

Publishing Venue

Motorola

Related People

Richard Carlson: AUTHOR

Abstract

A method to tune stripline transmission circuits is proposed. Stripline is a transmission medium composed of two ground planes that sandwich a strip conductor. Traditionally, these ground planes are solid conducting planes and are an integral part of the transmission medium. It is desirable in many circumstances to make the transmission medium electrically "tu,nable" to account for design and process variations. Stripline is difficult to tune with its solid ground planes. It's proposed that stripline could be made tunable through replacing one (or both) of the ground planes with a grid-like ground plane. Changes to the strip electrical characteristics could be made by judiciously cutting (laser or mill) open slots within the grid. Slots effectively would lower the capacitance between the strip and ground;

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MOTOROLA Technical Developments

A TUNABLE STRIPLINE MEDIUM

by Richard Carlson

  A method to tune stripline transmission circuits is proposed. Stripline is a transmission medium composed of two ground planes that sandwich a strip conductor. Traditionally, these ground planes are solid conducting planes and are an integral part of the transmission medium. It is desirable in many circumstances to make the transmission medium electrically "tu,nable" to account for design and process variations. Stripline is difficult to tune with its solid ground planes. It's proposed that stripline could be made tunable through replacing one (or both) of the ground planes with a grid-like ground plane. Changes to the strip electrical characteristics could be made by judiciously cutting (laser or mill) open slots within the grid. Slots effectively would lower the capacitance between the strip and ground;

effecting the electrical response of the transmission line. Several degrees of freedom are afforded with this method in that the slots can be cut both longitu- dinally and laterally from the strip. The resultant shape of the cut and its orientation may also have an advantageous effect on the resultant circuit frequency response. The gridded method can be selectively added to known sensitive tuning areas on a design. The grid need not be uniform and it can be inter- mingled with portions of solid ground plane. The concept could also be extended to broadside coupled line structures....