Broadband microstrip filter apparatus having inteleaved resonator sections
First Claim
1. A broadband microstrip filter apparatus, comprising:
- a microstrip structure including a ground plane, said ground plane having a dielectric disposed thereon, said dielectric having a top surface;
at least one first conductive line having a first plurality of conductive areas and a second plurality of conductive areas, said first conductive areas being located on said top surface of said dielectric and said second conductive areas being located a given distance beneath said top surface, each separate first and second conductive area having a leading edge and a trailing edge and wherein each of said first conductive areas has a respective trailing edge connected to the leading edge of an adjacent second conductive area, and each of said adjacent second conductive areas has a respective trailing edge connected to the leading edge of a next adjacent first conductive area, all of said first plurality of conductive areas being thereby connected with all of said second plurality of conductive areas to constitute said first conductive line having a square wave pattern;
at least one second conductive line having a third plurality of conductive areas and a fourth plurality of conductive areas, said third conductive areas being located on said top surface of said dielectric and said fourth conductive areas being located said given distance beneath said top surface, each separate third and fourth conductive area having a leading edge and a trailing edge and wherein each of said third conductive areas has a respective trailing edge connected to the leading edge of an adjacent fourth conductive area, and each of said adjacent fourth conductive areas has a respective trailing edge connected to the leading edge of a next adjacent third conductive area, all of said third plurality of conductive areas being thereby connected with all of said fourth plurality of conductive areas to constitute said second conductive line having a square wave pattern, said conductive areas of said first conductive line being disposed relative to said conductive areas of said second conductive line to constitute an interlace pattern, therebetween said third plurality and said second plurality of conductive areas being thereby constituted as a first plurality of capacitors wherein each one of said third conductive areas of said second line constitutes a respective top capacitive plate and a respective one of said second conductive areas of said first line constitutes an associated bottom capacitive plate, said first plurality and said fourth plurality of conductive areas being thereby constituted as a second plurality of capacitors wherein each one of said first conductive areas of said first line constitutes a respective top capacitive plate and a respective one of said fourth conductive areas of said second line constitutes an associated bottom capacitive plate, whereby said first and said second lines are constituted as resonator sections each including a given number of said capacitors with each number of said capacitors of a line length of a fractional wavelength at a frequency of an input microwave signal applied to said filter thereby constituting said microstrip filter apparatus; and
wherein said input microwave signal is applied to said microstrip filter apparatus and propagates along said first and said second lines, said microwave signal having an odd mode wave propagating between said first and said second lines and an even mode wave propagating between said first line and said ground plane and between said second line and said ground plane, respectively, and whereupon said even and said odd mode waves travel in synchronism along said first and said second lines of said microstrip filter apparatus.
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Accused Products
Abstract
A broadband microstrip filter structure employs a first transmission line which basically consists of a series of capacitor plates which extend between a dielectric layer from a first location to a second location and each of the series of plates are connected together with a top plate on the top surface of the dielectric and a bottom plate located a given distance beneath the dielectric layer. A second transmission line alternates between the top and bottom layers of the dielectric and consists of a second series of capacitive plates whereby each capacitor is connected to an adjacent capacitor with the top plate of the first connecting to the bottom plate of the second and the bottom plate of the first connecting to the top plate of the second and so on. This pattern is repeated so that the conductor path alternates from the top to the bottom plate. Various capacitors are selected to provide predetermined length resonators while various other capacitors are provided to provide coupling sections. In this configuration each of the above-noted lines provide switching from the top to the bottom so that each conductor averages the same distance from the ground plane insuring identical impedances in each line. The structure allows tight coupling and enables the even and odd mode phase velocity differences to be compensated for due to the fact that the odd mode travels between the two conductors and the even mode travels between the conductor and the ground plane. In this manner the odd mode travels faster but further, thus the even mode and the odd mode move down the structure in synchronism.
25 Citations
18 Claims
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1. A broadband microstrip filter apparatus, comprising:
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a microstrip structure including a ground plane, said ground plane having a dielectric disposed thereon, said dielectric having a top surface; at least one first conductive line having a first plurality of conductive areas and a second plurality of conductive areas, said first conductive areas being located on said top surface of said dielectric and said second conductive areas being located a given distance beneath said top surface, each separate first and second conductive area having a leading edge and a trailing edge and wherein each of said first conductive areas has a respective trailing edge connected to the leading edge of an adjacent second conductive area, and each of said adjacent second conductive areas has a respective trailing edge connected to the leading edge of a next adjacent first conductive area, all of said first plurality of conductive areas being thereby connected with all of said second plurality of conductive areas to constitute said first conductive line having a square wave pattern; at least one second conductive line having a third plurality of conductive areas and a fourth plurality of conductive areas, said third conductive areas being located on said top surface of said dielectric and said fourth conductive areas being located said given distance beneath said top surface, each separate third and fourth conductive area having a leading edge and a trailing edge and wherein each of said third conductive areas has a respective trailing edge connected to the leading edge of an adjacent fourth conductive area, and each of said adjacent fourth conductive areas has a respective trailing edge connected to the leading edge of a next adjacent third conductive area, all of said third plurality of conductive areas being thereby connected with all of said fourth plurality of conductive areas to constitute said second conductive line having a square wave pattern, said conductive areas of said first conductive line being disposed relative to said conductive areas of said second conductive line to constitute an interlace pattern, therebetween said third plurality and said second plurality of conductive areas being thereby constituted as a first plurality of capacitors wherein each one of said third conductive areas of said second line constitutes a respective top capacitive plate and a respective one of said second conductive areas of said first line constitutes an associated bottom capacitive plate, said first plurality and said fourth plurality of conductive areas being thereby constituted as a second plurality of capacitors wherein each one of said first conductive areas of said first line constitutes a respective top capacitive plate and a respective one of said fourth conductive areas of said second line constitutes an associated bottom capacitive plate, whereby said first and said second lines are constituted as resonator sections each including a given number of said capacitors with each number of said capacitors of a line length of a fractional wavelength at a frequency of an input microwave signal applied to said filter thereby constituting said microstrip filter apparatus; and wherein said input microwave signal is applied to said microstrip filter apparatus and propagates along said first and said second lines, said microwave signal having an odd mode wave propagating between said first and said second lines and an even mode wave propagating between said first line and said ground plane and between said second line and said ground plane, respectively, and whereupon said even and said odd mode waves travel in synchronism along said first and said second lines of said microstrip filter apparatus. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification