Methods of fabricating continuous transverse stub radiating structures and antennas

• US 5,771,567 A
• Filed: 08/29/1996
• Issued: 06/30/1998
• Est. Priority Date: 08/29/1996
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Dougherty, Thomas Kirk, Lee, Florentino V., Chen, William W., Pierce, Brian M., Harris, Norman H.
• Primary Examiner(s): Arbes, Carl J.
• Application Number:
  US08/705,508
• Time in Patent Office: 670 Days
• Field of Search: 29/25.35, 29/603, 29/600
• US Class Current: 29/600
• CPC Class Codes: C04B 18/02 Agglomerated materials , e.g. artificial aggregates
• CPC Class Codes: C04B 2111/00844 for electronic applications
• CPC Class Codes: C04B 35/465 based on alkaline earth metal titanates
• CPC Class Codes: C04B 38/06 by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
• CPC Class Codes: C04B 41/4515 application under vacuum or reduced pressure
• CPC Class Codes: C04B 41/48 Macromolecular compounds
• CPC Class Codes: C04B 41/51 Metallising , e.g. infiltration of sintered ceramic preforms with molten metal covering materials with metals in general C23C; ceramic compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides, other than as macroscopic reinforcing agents C22C; infiltration of preforms containing free metal, e.g. cermets C22C
• 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 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

Methods of fabricating a porous ceramic composite having voltage-variable dielectric properties. The composite is made as follows. A polycrystalline ferroelectric powder, which is a ferroelectric perovskite such as barium strontium titanate, for example, is provided. The powder, a binder and a filler are then mixed in water to form a slurry. The powder-binder-filler slurry is then dried. The dried powder-binder-filler slurry is granulated. The granulated powder-binder-filler is pressed into a die. The binder and filler are then burned out to form a fragile porous ash-like structure. The porous structure is then sintered to form porous ceramic parts. The porous ceramic parts are then machined tiles. The machined porous tiles may then be tested for microwave properties. Fabrication methods for producing porous ferroelectric ceramic-polymer composite tiles or subaperture blanks and continuous transverse stub electronically scanned antenna plates or subapertures are also disclosed.

Claims

1. A method of fabricating a radiating structure for use in a continuous transverse stub electronically-scannable antenna, said method comprising the steps of:

providing porous tiles;

assembling a fixture containing a plurality of porous tiles;

infiltrating the assembly of porous tiles with a polymer precursor to form a ceramic polymer composite;

curing the assembly of infiltrated porous tiles;

machining the cured assembly;

metallizing a stub face of the assembly;

attaching the metallized stub face to a support plate; and

metallizing a back face of the assembly to form a radiating structure.

2. The method of claim 1 wherein the step of providing porous tiles comprises the steps of:

providing a polycrystalline ferroelectric powder;

mixing the powder, a binder and a filler in water to form a slurry;

drying the powder-binder-filler slurry;

granulating the dried powder-binder-filler slurry;

pressing the granulated powder-binder-filler into a die;

burning out the binder and filler to form a porous structure;

sintering the porous structure to form porous ceramic parts; and

machining the porous ceramic parts to provide the porous tiles.

3. The method of claim 2 wherein the polycrystalline ferroelectric powder is a ferroelectric perovskite.

4. The method of claim 2 wherein the ferroelectric perovskite is barium strontium titanate.

5. The method of claim 2 further comprising the step of testing the machined porous tiles for microwave properties.

6. The method of claim 1 further comprising the step of testing the metallized assembly.

7. The method of claim 1 wherein the step of infiltrating the assembly of porous tiles comprises the step of infiltrating the porous ceramic part under vacuum.

8. The method of claim 1 further comprising additional steps required to form a continuous transverse stub electronically-scannable antenna, said additional steps comprising:

bonding the back face of the assembly to a cold plate;

bonding loads to the assembly;

lapping tops of the stubs;

bonding a superstrate to the assembly; and

machining the superstrate to form the continuous transverse stub electronically-scannable antenna.