LIQUID DIELECTRIC COOLED TERMINATIONS

• US 3,783,414 A
• Filed: 02/06/1973
• Issued: 01/01/1974
• Est. Priority Date: 02/06/1973
• Status: Expired due to Term

• Current Assignee: Edward R. Mittelman, Gerald I. Klein
• Original Assignee: Edward R. Mittelman, Gerald I. Klein
• Inventors: Klein, Gerald I., Mittelman, Edward R.
• Primary Examiner(s): Rolinec, Rudolph V.
• Assistant Examiner(s): Nussbaum, Marvin
• Application Number:
  US05/330,156
• Time in Patent Office: 329 Days
• Field of Search: 333/22R,22F,81B
• US Class Current: 333/22.00F
• CPC Class Codes: H01P 1/262 the dissipative medium being a liquid or being cooled by a liquid

Abstract

A termination for terminating or absorbing a signal transmitted along a transmission line is disclosed as comprising a short circuit disposed across the transmission line and a thin film of a resistive material disposed a critical length from the short circuit to absorb substantially the signal transmitted along the transmission line. A cooling chamber is formed about the thin film and a cooling liquid of given dielectric constant and relatively low microwave loss is directed through said cooling chamber to remove the heat absorbed by the thin film. A window is disposed across the transmission line to form the cooling chamber. The cooling liquid of given dielectric constant acts as a matching transformer to reduce the impedance seen by a wave propagated along the transmission line. The resistivity or impedance of the thin film is selected to be substantially equal to that of the transformed impedance effected by the cooling liquid. To establish the desired matching transformer, the spacing between the window and the resistive film is selected to be an odd integral multiple of one-fourth the wavelength of a signal as transmitted through the cooling liquid. Further, to ensure that the resistive film absorbs substantially the energy of the signal transmitted along the transmission line, the aforementioned critical distance is selected to be an odd integral multiple of one-fourth the wavelength of the signal as transmitted through the cooling medium. The given dielectric constant of the cooling medium in turn determines the wavelength of a signal transmitted therethrough, and therefore the spacings between the window and the resistive film, and the resistive film and the short circuit.

Claims

1. Apparatus for absorbing energy from a signal transmitted along a transmission line having a characteristic impedance, said apparatus comprising:

a. short circuit means disposed across said transmission line;

b. a film disposed across substantially the entire cross-section of said transmission line;

c. means for forming a cooling chamber including a first section disposed between said film and said short circuit means and a second section in front of said film with respect to said short circuit means; and

d. a cooling liquid disposed within said cooling chamber and having a given dielectric constant and low microwave loss;

e. the distances along the length of said transmission line from said film to said short circuit means and from said film to the periphery of said cooling chamber being determined to be N lambda g/4, where N is any odd integral number and lambda g is the wavelength of a signal transmitted in said cooling liquid;

f. said cooling liquid in said second section of said cooling chamber transforming the impedance seen by the transmitted signal along said transmission line, said film having an impedance substantially equal to the reduced impedance of said transmission line as transformed by said cooling liquid.

2. Apparatus as claimed in claim 1, wherein there is included means for directing said cooling liquid through said cooling chamber.

3. Apparatus as claimed in claim 2, wherein said directing means includes pump means for circulating said cooling liquid through a first conduit to said cooling chamber and a second conduit from said cooling chamber to said pump means.

4. Apparatus as claimed in claim 3, wherein said directing means includes heat exchanger means for dissipating the absorbed heat from said cooling liquid.

5. Apparatus as claimed in claim 1, wherein said cooling chamber defining means includes a window disposed substantially across the cross-section of said transmission line.

6. Apparatus as claimed in claim 5, wherein there is included a first O-ring disposed to form a liquid-tight seal between a first surface of said window and said second section of said cooling chamber and a second 0-ring dispoSed to form an air and liquid-tight seal between a second surface of said window and the remaining portion of said transmission line.

7. Apparatus as claimed in claim 6, wherein there is included means for supporting said window with respect to said transmission line, said supporting means includes a plurality of openings disposed therethrough to permit cooling liquid inadvertently leaked through said first O-ring to be discharged from said supporting means.

8. Apparatus as claimed in claim 1, wherein said film is supported upon a substrate within said cooling chamber.

9. Apparatus as claimed in claim 1, wherein said cooling liquid has a loss tangent not greater than 0.05.