Antenna system

• US 20050062665A1
• Filed: 07/21/2004
• Published: 03/24/2005
• Est. Priority Date: 09/24/2003
• Status: Active Grant

• Current Assignee: Gas Technology Institute
• Original Assignee: Gas Technology Institute
• Inventors: Lehmensiek, Robert, du Toit, Leendert Johannes
• Granted Patent: US 7,034,768 B2
• Time in Patent Office: Days
• US Class Current: 343/789
• CPC Class Codes: E21B 47/13 by electromagnetic energy, e.g. radio frequency
• CPC Class Codes: E21B 7/04 Directional drilling
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 7/4008 of transmitters
• CPC Class Codes: G01V 3/30 operating with electromagnetic waves
• CPC Class Codes: H01Q 1/04 Adaptation for subterranean or subaqueous use
• CPC Class Codes: H01Q 1/40 Radiating elements coated with or embedded in protective material
• CPC Class Codes: H01Q 9/36 with top loading
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

An underground telemetry system having an antenna system having at least one metallic radiating element having a single or a dual top loaded folded monopole configuration and disposed within a metallic housing and having RF electronics to self-calibrate and tune the input impedance of the antenna elements.

Claims

1. An antenna system comprising:

one of a solid and a hollow metallic substantially cylindrical element having opposed first and second ends and forming a cavity along a longitudinal section thereof, said cavity having at least one peripheral wall;

at least one metallic radiating element adapted to radiate a radiation lobe substantially only in a direction of at least one of said first end and said second end disposed within said cavity;

a filler material disposed within said cavity; and

a radome covering said cavity, said radome being flush with an outer surface of said metallic cylindrical element.

2. An antenna system in accordance with claim 1, wherein said at least one metallic radiating element comprises a metallic material having a form selected from the group consisting of wire, rod, strip and ribbon.

3. An antenna system in accordance with claim 2, wherein said at least one metallic radiating element comprises at least one elongated segment oriented parallel to a longitudinal axis of said solid metallic cylindrical element and at least one connecting segment connecting said at least one elongated segment with said at least one peripheral wall.

4. An antenna system in accordance with claim 1 further comprising at least one tuning means for self-tuning said antenna system and at least one calibration means for self-calibrating said antenna system and a source/receiver excitation system.

5. An antenna system in accordance with claim 4, wherein said at least one tuning means comprises means for tuning said at least one metallic radiating element to an impedance of about 50 ohms at a frequency of interest.

6. An antenna system in accordance with claim 5, wherein said tuning means comprises an array of delay lines connected in a switchable combination and physically incorporated into one of a printed circuit board and a discretely packaged RF circuitry.

7. An antenna system in accordance with claim 1, said antenna system integral with one of a drill head and a drill string of an in-ground directional drilling apparatus.

8. In an underground telemetry system comprising an antenna system comprising at least one metallic radiating element, the improvement comprising:

said at least one metallic radiating element having one of a single and a dual top loaded folded monopole configuration and disposed within a metallic housing.

9. An underground telemetry system in accordance with claim 8, wherein said metallic housing is a solid metallic cylinder having opposed first and second ends and forming a cavity along a longitudinal section thereof, said cavity having at least one peripheral wall.

10. An underground telemetry system in accordance with claim 9, wherein a filler material is disposed within said cavity and said cavity is covered by a radome which is flush with an outer surface of said solid metallic cylinder.

11. An underground telemetry system in accordance with claim 8, wherein said at least one metallic radiating element comprises a metallic material having a form selected from the group consisting of wire, rod, strip and ribbon.

12. An underground telemetry system in accordance with claim 8 further comprising at least one tuning means for self-tuning said antenna system and at least one calibration means for self-calibrating said antenna system.

13. An underground telemetry system in accordance with claim 12, wherein said at least one tuning means comprises means for tuning said at least one metallic radiating element to an impedance of about 50 ohms at a frequency of interest.

14. An underground telemetry system in accordance with claim 13, wherein said at least one tuning means comprises an array of delay lines connected in a switchable combination and physically incorporated into a printed circuit board.

15. An underground telemetry system in accordance with claim 9, wherein said at least one metallic radiating element is oriented to radiate a radiation lobe substantially only in a direction of at least one of said first end and said second end of said solid metallic cylinder.