Lattice network using distributed impedance transmission lines

Claim 2

A four terminal coupling network comprising: a first radio frequency distributed transmission line formed from a conductor connected to a first terminal of said network and a separate conductor connected to the second terminal of said network, a second radio frequency distributed transmission line formed from a conductor connected to said second terminal of said network and a separate conductor connected to the third terminal of said network, a third radio frequency distributed transmission line formed from a conductor connected to said third terminal and a separate conductor connected to the fourth terminal of said network, and a fourth radio frequency distributed transmission line formed from a conductor connected to said fourth terminal and a separate conductor connected to said first terminal, means for coupling an input signal of a certain phase across said first and third terminals of said network and means connected to said second and fourth terminals for coupling an output signal of a certain phase from said network, and means by which said distributed transmission lines are formed with selected lengths and with a selected one of open and short circuit termination to determine the impedance across said terminals and the transmission characteristics of said network.

Claim 3

The combination as claimed in Claim 1 wherein said first and third distributed transmission lines are staggered transmission lines with said conductors thereof being broad conductive metal plates with said plates being in staggered parallel relationship with respect to each other with an edge of one metal plate being closely spaced with a non-corresponding edge of the other and with the maximum overlap of said metal plates being less than one half the width of either metal plate.

Claim 4

The combination as claimed in claim 2, wherein said second and fourth distributed transMission lines are microstrip transmission lines.

Claim 5

A lattice network capable of operating over a given range of microwave frequencies comprising: a dielectric substrate, a first relatively broad metal strip attached to one surface of said substrate, a second relatively broad metal strip attached to the opposite surface of said dielectric substrate, said second metal strip being oriented in staggered parallel relationship to the first metal strip with an edge of one metal strip being closely spaced with a non-corresponding edge of the other and with the maximum overlap of said metal strips being less than one half the width of either metal strip, a first narrow slot extending from a first point along the closely spaced edge of said first metal strip in a direction so as to substantially divide said first metal strip into a first and a second section to provide a first slot transmission line on said one surface of said dielectric substrate, a second narrow slot extending from a point along the closely spaced edge of said second metal strip in a direction away from said first metal strip to divide said second metal strip into first and second sections to provide a second slot transmission line, said point along said edge of said second metal strip being on said opposite surface and adjacent to said point along the closely spaced edge of said first metal strip, said first section of said first metal strip and said first section of said second metal strip providing a first staggered transmission line extending in a first direction away from the adjacent points and said second section of said first metal strip and said second section of said second metal strip forming a second staggered transmission line extending in a direction opposite said first direction away from said adjacent points, the spacing between the metal strips and the dielectric constant of the medium therebetween being determined so that the electromagnetic fields associated with an electromagnetic wave coupled to the staggered transmission lines are essentially confined to the region between the metal strips, a first narrow strip-like conductor extending from said first section of said first metal strip to a point above said second section of said second metal strip to form a first microstrip transmission line, a second narrow strip-like conductor extending from the first section of said second metal strip to a point below the second section of said first metal strip to form a second microstrip transmission line, said staggered transmission lines and said microstrip transmission lines having their lengths and their type of terminations chosen to control the transmission characteristics of said network.

Claim 6

A lattice network capable of operating over a given range of microwave frequencies comprising: a dielectric substrate, a first relatively broad metal strip attached to one surface of said substrate, a second relatively broad metal strip attached to the opposite surface of said dielectric substrate, said second metal strip being oriented in staggered parallel relationship to the first metal strip with an edge of one metal strip being closely spaced with a non-corresponding edge of the other and with the maximum overlap of said metal strips being less than one half the width of either metal strip, a first narrow slot extending from a first point along the closely spaced edge of said first metal strip in a direction so as to substantially divide said first metal strip into a first and a second section to provide a first slot transmission line on said one surface of said dielectric substrate, a second narrow slot extending from a point along the closely spaced edge of said second metal strip in a direction away from said first metal strip to divide said second metal strip into first and second sections to provide a second slot transmission line, said point along said edge of said second metal strip being on said opposite surface and adjacent to said point along the closely spaced edge of said first metal strip, said first section of said first metal strip and said first section of said second metal strip providing a first staggered transmission line extending in a first direction away from the adjacent points and said second section of said first metal strip and said second section of said second metal strip forming a second staggered transmission line extending in a direction opposite said first direction away from said adjacent points, the spacing between the metal strips and the dielectric constant of the medium therebetween being determined so that the electromagnetic fields associated with an electromagnetic wave coupled to the staggered transmission lines are essentially confined to the region between the metal strips, a first narrow strip-like conductor extending from said first section of said first metal strip to a point above said second section of said second metal strip to form a first microstrip transmission line, a second narrow strip-like conductor extending from the first section of said second metal strip to a point below the second section of said first metal strip to form a second microstrip transmission line, said staggered transmission lines and said microstrip transmission lines having their lengths and their type of terminations chosen to control the transmission characteristics of said network.

Claim 7

The combination as claimed in claim 4, including a third and a fourth narrow strip-like conductor, said third narrow strip-like conductor located on said one surface and extending parallel to and directly above said second metal strip, said third narrow strip-like conductor oriented substantially perpendicular to said second slot in said second metal strip for coupling signals along said second slot between said third narrow strip-like conductor and said second metal strip, said fourth narrow strip-like conductor located on said opposite surface and spaced from said first relatively broad metal strip, said fourth narrow strip-like conductor oriented orthogonal to said first slot transmission line in said first metal strip for coupling to signals propagating along said first slot transmission line.

Claim 8

The combination as claimed in claim 4, wherein said first section of said first metal strip is connected to the first section of the second metal strip and the second section of said first metal strip is connected to the second section of the second metal strip with said connecting points being located an equal distance from the adjacent points.

Claim 9

The combination as claimed in claim 6, wherein said distance is a quarter wavelength long at the center operating freQuency of the lattice network.

Claim 10

The combination as claimed in claim 7, wherein said narrow strip-like conductors are each a quarter wavelength long at the center frequency of the network.

Claim 11

The combination as claimed in claim 8, wherein said narrow strip-like conductors are short circuited at the ends so as to provide a band reject filter.