Antenna system using time delays with mercury wetted switches

• US 6,191,754 B1
• Filed: 03/18/1999
• Issued: 02/20/2001
• Est. Priority Date: 08/18/1998
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: Northrop Grumman Corporation
• Inventors: Freidhoff, Carl B., Hopwood, F. William, Adam, J. Douglas, Smith, Thomas J. Jr., Degenford, James E., Nathanson, Harvey C.
• Primary Examiner(s): Ho, Tan
• Application Number:
  US09/271,833
• Time in Patent Office: 705 Days
• Field of Search: 343/853, 343/876, 333/138, 333/141, 333/156, 333/258, 335/47, 342/368, 342/374, 342/375
• US Class Current: 343/876
• CPC Class Codes: H01H 1/08 wetted with mercury
• CPC Class Codes: H01H 2029/008 using micromechanics, e.g. micromechanical liquid contact switches or [LIMMS]
• CPC Class Codes: H01H 29/00 Switches having at least one liquid contact solid contacts wetted or soaked with mercury H01H1/08
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

An electronically steerable antenna array which includes time delay units connected to individual antenna elements for time delaying a microwave signal to and/or from the antenna elements. Each time delay unit includes small mercury wetted switches for controlling signal flow via a time delay path or a bypass path, through the time delay unit from a signal input to a signal output.

Claims

1. An electronically steerable antenna array system, comprising:

(A) a plurality of antenna elements;

(B) a plurality of time delay units connected in signal transfer relationship with a selected one of said antenna elements;

(C) each said time delay unit including a signal input and signal output and a plurality of microstrip delay line stages each stage having a delay line segment and bypass segment selectively insertable in circuit between said input and said output;

(D) said delay line stages being electrically connected in series by respective interstage connectors;

(E) a plurality of mercury wetted switches connected to said delay line stages and operable upon application of predetermined control signals to selectively insert predetermined ones of said delay line segments into said circuit;

(F) each said mercury wetted switch including three microstrip conductors, one of said conductors being electrically connectable with a said delay line segment, another of said conductors being electrically connectable with a said bypass segment and another of said conductors being electrically connectable with a said interstage connector;

(G) each said conductor including a mercury droplet which forms electrical contact with a mercury droplet of one of said other conductors upon the application of said predetermined control signals.

2. A system according to claim 1 wherein:

(A) respective ones of said microstrip conductors of said mercury wetted switch are respectively integral with said delay line segment, said bypass segment and said interstage connector.

3. A system according to claim 1 wherein:

(A) said delay line stages are of progressively smaller delay times.

4. A system according to claim 3 wherein:

(A) said time delay unit including at least nine said delay line stages providing a delay from a minimum delay to a maximum delay of 2.044 ns, in 4 ps increments.

5. A system according to claim 1 wherein:

(A) each said mercury wetted switch includes four mercury droplets for connecting an interstage connector with a selected one of said delay line segment and bypass segment.

6. A system according to claim 1 wherein:

(A) each said mercury wetted switch includes three mercury droplets for connecting an interstage connector with a selected one of said delay line segment or bypass segment.

7. A system according to claim 1 wherein:

(A) each said mercury wetted switch has an on resistance Ron which is on the order of 20 milliohms.

8. A system according to claim 1 wherein:

(A) each said mercury wetted switch has an off capacitance C_off which is on the order of 2.5×

10<sup>−

14</sup> farads.

9. A system according to claim 1 wherein:

(A) each said time delay unit is encased in a package having electrically conducting and electrically joined top and bottom cover members.

10. A system according to claim 9 wherein:

(A) said top and bottom cover members are electrically joined by a plurality of electrically conducting posts positioned adjacent said delay line segments, bypass segments and interstage connectors.

11. A system according to claim 10 wherein:

(A) said posts are spaced at a distance of at less than {fraction (1/10)}λ

from one another, where λ

is the wavelength of the highest frequency of interest.

12. A system according to claim 9 wherein:

(A) said package has a measurement of less than λ

, where λ

is the wavelength of the highest frequency of interest.

13. A system according to claim 12 wherein:

(A) said package is rectangular and has a measurement of around 0.6λ

×

0.6λ

.