Dielectric substrate with selectively controlled effective permittivity and loss tangent

• US 6,911,941 B2
• Filed: 06/19/2003
• Issued: 06/28/2005
• Est. Priority Date: 06/19/2003
• Status: Expired due to Fees

• Current Assignee: North South Holdings Incorporated (Spherix Incorporated)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Chappell, William Johnson, Tebbe, Dennis, Smyth, Thomas
• Primary Examiner(s): Dinh, Trinh Vo
• Application Number:
  US10/465,074
• Publication Number:
  US 20040257279A1
• Time in Patent Office: 740 Days
• Field of Search: H01/Q00.1/38, C03/B02.9/00, 343/700.MS, 343/756, 343/909, 333/128, 333/204, 333/108, 156/89.11, 156/89.12, 296/00
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 15/006 Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces
• CPC Class Codes: H05K 1/024 Dielectric details, e.g. changing the dielectric material around a transmission line
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 2203/063 of preperforated insulating layer
• CPC Class Codes: H05K 3/4611 by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: H05K 3/4629 laminating inorganic sheets comprising printed circuits, e.g. green ceramic sheets
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

A substrate (300) for an RF device includes a plurality of layers (102) of dielectric material cofired in a stack. The plurality of layers (102) is formed from a material having a permittivity. Selected ones of the layers (102) have a pattern of perforations (106) formed in at least one perforated area (104). The perforated areas (104) are generally aligned with one another in the stack to lower one or more of an effective value of a permittivity and a loss tangent in a least one spatially defined region (504) of the substrate (300).

Claims

1. A method for fabricating a substrate for an RF device, comprising steps of:

forming a pattern of perforations in a plurality of layers of an unfired ceramic tape in at least one perforated area of each layer;

laminating said plurality of layers in a stack with said at least one perforated area in each of said plurality of layers at least partially aligned with at least one perforated area of an adjacent one of said plurality of layers in said stack to lower at least one of an effective value of a permittivity and an effective value of a loss tangent in a least one spatially defined region of said substrate, as compared to a bulk value of permittivity and loss tangent for said dielectric material;

firing said laminated stack.

2. The method according to claim 1 further comprising a step of aligning said perforations of each said perforated area.

3. The method according to claim 1 further comprising a step of selecting said ceramic tape to be a low temperature cofired ceramic tape.

4. The method according to claim 1 further comprising a step of forming an RF circuit component on said substrate.

5. The method according to claim 1 further comprising a step of excluding said pattern of perforations from at least one outermost layer of said substrate.

7. The method according to claim 1 further comprising a step of varying said pattern among said plurality of layers.

8. The method according to claim 1 further comprising a step of off setting said pattern from layer to layer.

9. The method according to claim 1 further comprising a step of sealing said spatially defined region from an external environment.

10. The method according to claim 1 further comprising a step of forming said pattern of perforations in a plurality of said perforated areas of each said layer to produce a plurality of said spatially defined regions, each having said effective value of permittivity lower than said permittivity.

6. A method for fabricating a substrate for an RF device, comprising steps of:

forming a pattern of perforations in a plurality of layers of a dielectric material in at least one perforated area of each layer;

arranging said plurality of layers in a stack with said at least one perforated area in each of said plurality of layers at least partially aligned with one another in said stack to lower at least one of an effective value of a permittivity and an effective value of a loss tangent in a least one spatially defined region of said substrate, as compared to a bulk value of permittivity and loss tangent for said dielectric material;

selecting said pattern for each of said plurality of layers so that said effective value of permittivity is substantially the same at each measurable point of said spatially defined region of said substrate.

11. A method for fabricating a substrate for an RF device, comprising steps of:

forming a pattern of perforations in a plurality of layers of a dielectric material in at least one perforated area of each layer;

arranging said plurality of layers in a stack with said at least one perforated area in each of said plurality of layers at least partially aligned with one another in said stack to lower at least one of an effective value of a permittivity and an effective value of a loss tangent in a least one spatially defined region of said substrate, as compared to a bulk value of permittivity and loss tangent for said dielectric material;

forming said pattern of perforations in a plurality of said perforated areas of each said layer to produce a plurality of said spatially defined regions, each having said effective value of permittivity lower than said permittivity;

selecting said pattern of perforations in said plurality of perforated areas to produce a value for said effective permittivity in said plurality of said spatially defined regions that is different as compared to areas of said layers that are not perforated.

12. A method for fabricating a substrate for an RF device, comprising steps of:

forming a pattern of perforations in a plurality of layers of a dielectric material in at least one perforated area of each layer;

arranging said plurality of layers in a stack with said at least one perforated area in each of said plurality of layers at least partially aligned with one another in said stack to lower at least one of an effective value of a permittivity and an effective value of a loss tangent in a least one spatially defined region of said substrate, as compared to a bulk value of permittivity and loss tangent for said dielectric material;

selecting said pattern of perforations in each of said layers to cause said effective permittivity to selectively vary in a predetermined manner across a surface of said substrate defined by said spatially defined region.