Hermetically-sealed electrically-absorptive low-pass radio frequency filters and electromagnetically lossy ceramic materials for said filters

• US 5,942,842 A
• Filed: 08/25/1998
• Issued: 08/24/1999
• Est. Priority Date: 02/07/1992
• Status: Expired due to Fees

• Current Assignee: Homer William Jr. Fogle
• Original Assignee: Homer William Jr. Fogle
• Inventors: Fogle, Homer William Jr.
• Primary Examiner(s): JOHNSON, STEPHEN
• Application Number:
  US09/139,517
• Time in Patent Office: 364 Days
• Field of Search: 313/313, 313/134, 313/136, 315/59, 315/71, 102/202.2
• US Class Current: 313/313
• CPC Class Codes: F42B 3/18 Safety initiators resistant to premature firing by static electricity or stray currents
• CPC Class Codes: F42B 3/188 having radio-frequency filters , e.g. containing ferrite cores or inductances F42B3/185 takes precedence

Abstract

An electromagnetically lossy liquid- or gas-tight fusion seal for use as a low pass radio frequency signal filter constructed as a matrix of glass binder and ferrimagnetic and/or ferroelectric filler. Metal cased electrical filters are made by reflowing the material to form fused glass-to-metal seals and incorporating electrical thru-conductors therein which may be formed as inductive windings.

Claims

1. A composition for a solid electromagnetically lossy substantially gas-impermeable plug comprising

a dense vitreous ceramic matrix of (a) a multi-component glass binder, 5-50% by weight, and (b) at least one electromagnetically lossy ferrimagnetic and/or ferroelectric filler interspersed throughout, 50-95% by weight, said ceramic matrix having mechanical and electrical properties of

linear expansion coefficient adaptable by formulation to values in the range of 3 to 20 ppm/°

C.,

helium permeability not greater than 2×

10^-11 darcys,

working point adaptable by formulation to values in the range of 400 to 1000°

C.,

strain point adaptable by formulation to values in the range of 250 to 700°

C.,

Curie temperature adaptable by formulation to values in the range of 130 to 600°

C.,

DC electrical volume resistivity adaptable by formulation to values in excess of 100 ohm-cm,

dielectric strength in excess of 150 volts/mil, and

unguided wave attenuation constant greater than 1 neper/meter at 1 MHz, and greater than 5 nepers/meter at 10 MHz and above.

2. The composition of claim 1, the glass binder including a Lead Borosilicate glass composed of Lead Oxide, Lead Silicate, Boron Oxide and Aluminum Oxide.

3. The composition of claim 1, the binder including a Lead Boroaluminosilicate glass composed of Silica, Aluminum Oxide, Boron Oxide, and Lead Oxide.

4. The composition of claim 1, the lossy ferrimagnetic filler comprising spinel ferrite having the general formula (AaO)_1-x (BbO)_x Fe₂ O₃, where Aa and Bb are divalent metal cations comprising Ba, Cd, Co, Cu, Fe, Mg, Mn, Ni, Sr or Zn, and x is a fractional number on the interval (0,1).

5. The composition of claim 1, the lossy ferroelectric filler comprising perovskite titanate of the type (CcO)TiO₂, or a zirconate of the type (CcO)ZrO₂, where Cc is a divalent metal cation of Ba, La, Sr or Pb.

6. The ceramic material of claim 1, the lossy ferroelectric filler comprising a perovskite La-modified Lead Zirconium Titanate.

7. A composition for a solid electromagnetically lossy substantially gas-impermeable plug comprising

a dense vitreous ceramic matrix of (a) a multi-component glass binder, 5-50% by weight, and (b) at least one electromagnetically lossy ferrimagnetic and/or ferroelectric filler interspersed throughout, 50-95% by weight, said ceramic matrix having mechanical and electrical properties of

linear expansion coefficient adaptable by formulation to values in the range of 3 to 20 ppm/°

C.,

helium permeability not greater than 2×

10^-11 darcys,

working point adaptable by formulation to values in the range of 400 to 1000°

C.,

strain point adaptable by formulation to values in the range of 250 to 700°

C.,

Curie temperature adaptable by formulation to values in the range of 130 to 600°

C.,

DC electrical volume resistivity adaptable by formulation to values in excess of 100 ohm-cm,

dielectric strength in excess of 150 volts/mil, and

unguided wave attenuation constant greater than 1 neper/meter at 1 MHz, and greater than 5 nepers/meter at 10 MHz and above,

the binder including a Lead Borosilicate glass composed of Lead Oxide, Lead Silicate, Boron Oxide and Aluminum Oxide, or a Lead Boroaluminosilicate glass composed of Silica, Aluminum Oxide, Boron Oxide, and Lead Oxide,

the lossy ferrimagnetic filler comprising spinel ferrite having the general formula (AaO)_1-x (BbO)_x Fe₂ O₃, where Aa and Bb are divalent metal cations comprising Ba, Cd, Co, Cu, Fe, Mg, Mn, Ni, Sr or Zn, and x is a fractional number on the interval (0.,

     1),

the lossy ferroelectric filler comprising perovskite titanate of the type (CcO) TiO₂, or a zirconate of the type (CcO)ZrO₂, where Cc is a divalent metal cation of Ba, La, Sr or Pb, or a perovskite La-modified Lead Zirconium Titanate.