US3584293A — Elements for steering the beam of helical antenna…

Claim 1

Independent Claim 401 words

In a subsurface earth formation exploration tool for logging an earth formation penetrated by a borehole to approximate the distance and direction to an electromagnetic discontinuity in said formation from said borehole by measuring the two-way travel time of electromagnetic energy generated by means of an energization circuit including a source of electromagnetic energy and a control circuit means, uphole or interior of said tool, a helical antenna supported within said tool for irradiating said formation with a two-condition, selectively variable pattern of electromagnetic radiation, in azimuth, comprising: a. a central conducting element axially elongated substantially along the axis of said well bore, b. at least N pair(s) of helical conducting elements wound axially along and radially spaced outwardly from said central element, where N is any whole number greater than zero, each helical conducting element of each N pair(s) of elements winding in the same circumferential direction about said central element toward a common end of said central element, c. switching coupler means positioned interior of said central element and including a plurality of feed points positioned along said helical antenna for coupling, from said energization circuit, electromagnetic energy between said central element and said N pair(s) of helical elements, and condition means operatively connected to and controlled by said control circuit means for coupling, among said plurality of feed points, electromagnetic energy to a first subset of feed points in a first discrete operating state so as to produce, along said antenna, at least N coextensively propagating pair(s) of electromagnetic waves propagating in phase along said antenna in a common axial direction, said N pair(s) of electromagnetic energy radiating from said antenna in phase into said adjacent earth formation in planes substantially transverse to the axis of said well bore to produce a uniform, omnidirectional transversE radiation pattern, said conditioning means, in a second discrete operating state, in response to a change in condition within said control circuit means, sequentially decoupling N adjacent feed point(s) of said subset of feed points from operative contact with said energization circuit and then coupling N end feed point(s) to said energization circuit whereby N pair(s) of coextensively propagating electromagnetic waves are produced, said N pair(s) of electromagnetic waves, in said second discrete operating state, each traveling in opposite axial directions along said antenna but interacting so as to irradiate, into such adjacent earth formation, a highly directional, figure-eight pattern of electromagnetic energy.

Claim 2

Dependent Claim 401 words

In a subsurface earth formation exploration tool for logging an earth formation penetrated by a borehole to approximate the distance and direction to an electromagnetic discontinuity in said formation from said borehole by measuring the two-way travel time of electromagnetic energy generated by means of an energization circuit including a source of electromagnetic energy and a control circuit means, uphole or interior of said tool, a helical antenna supported within said tool for irradiating said formation with a two-condition, selectively variable pattern of electromagnetic radiation, in azimuth, comprising: a. a central conducting element axially elongated substantially along the axis of said well bore, b. at least N pair(s) of helical conducting elements wound axially along and radially spaced outwardly from said central element, where N is any whole number greater than zero, each helical conducting element of each N pair(s) of elements winding in the same circumferential direction about said central element toward a common end of said central element, c. switching coupler means positioned interior of said central element and including a plurality of feed points positioned along said helical antenna for coupling, from said energization circuit, electromagnetic energy between said central element and said N pair(s) of helical elements, and condition means operatively connected to and controlled by said control circuit means for coupling, among said plurality of feed points, electromagnetic energy to a first subset of feed points in a first discrete operating state so as to produce, along said antenna, at least N coextensively propagating pair(s) of electromagnetic waves propagating in phase along said antenna in a common axial direction, said N pair(s) of electromagnetic energy radiating from said antenna in phase into said adjacent earth formation in planes substantially transverse to the axis of said well bore to produce a uniform, omnidirectional transversE radiation pattern, said conditioning means, in a second discrete operating state, in response to a change in condition within said control circuit means, sequentially decoupling N adjacent feed point(s) of said subset of feed points from operative contact with said energization circuit and then coupling N end feed point(s) to said energization circuit whereby N pair(s) of coextensively propagating electromagnetic waves are produced, said N pair(s) of electromagnetic waves, in said second discrete operating state, each traveling in opposite axial directions along said antenna but interacting so as to irradiate, into such adjacent earth formation, a highly directional, figure-eight pattern of electromagnetic energy.

Claim 3

Dependent Claim 70 words

The helical antenna of claim 1 in which N 1, whereby one pair of electromagnetic waves is generated between one pair of helical conducting elements and said central element, and, in said first discrete operating state, propagate along said central element in a common axial direction but, in said second discrete operating state, said waves of said one pair of waves propagate in opposite axial directions along said central element.

Claim 4

Dependent Claim 149 words

The helical antenna of claim 1 in which N 2, whereby first and second pairs of electromagnetic waves are generated between first and second pairs of helical conducting elements and said central element, in said first discrete operating state, each pair of electromagnetic waves begin substantially at the midplane of said central element and coextensively propagate in the same axial direction toward a common end of said central element to generate said omnidirectional transverse radiation pattern in said formation, said first pair propagating in an opposite axial direction as said second pair of waves, in said second discrete state, an individual first or second electromagnetic wave of each first and second pairs of waves propagates in coextensive relationship with another individual wave of the same pair of waves but in an opposite axial direction as said another wave so as to generate said directional, figure-eight pattern of electromagnetic radiation.

Claim 5

Dependent Claim 95 words

The helical antenna of claim 3 with the addition of phase shifting means electrically connected to said control circuit means and operated thereby, in said second discrete operating state, to selectively shift the phase of said first and second pairs of electromagnetic waves propagating between said first and second pairs of helical conducting elements and said central element so as to cause selective steerage, in azimuth, of said figure-eight pattern of radiation relative to the axis of said borehole and thereby aid in identifying the azimuthal direction of said discontinuity relative to said borehole axis.

Claim 6

Dependent Claim 64 words

The helical antenna of claim 4 with the addition of first and second phase shifting means equipped with two settings of 0* and 180* phase shifts electrically controlled by said control circuit and operative in said first and second discrete operating settings to shift the polarizing mode of said first and second pairs of electromagnetic waves from a first to a second polarizing mode.

Claim 7

Dependent Claim 164 words

The helical antenna of claim 3 in which said switching coupler is further characterized by a series of segmented conductor means interior of said central element, said series of conducting means joined together at a series of junctions interior of said central element and terminating in a plurality of terminating segments, said first subset of feed points in said first discrete operating state comprising four centrally disposed feed points connecting, through said terminal segments, said first and second pairs of helical conducting elements and said central element to said source of electromagnetic energy, said four central feed points defining corners of an imaginary parallelogram lying in a plane through said switching coupler, one set of adjacent diagonally located feed points being connected in series with said source of electromagnetic energy through selected lengths of said segmented conductor means so as to couple electromagnetic energy to said helical elements in a phase opposite to that coupled to the remaining set of diagonally located feed points.

Claim 8

Dependent Claim 101 words

The helical antenna of claim 6 in which said condition means is further characterized by first and second switch means each located adjacent to a remote end of said central element as measured from the midplane thereof, in said second discrete operating state, said first and second switch means operating to decouple said one set of adjacent diagonally located feed points from contact with said source of energy and then couple said source to said end feed points remote from said midplane to launch electromagnetic waves along said antenna in an opposite axial direction than in said first discrete operating state.

Claim 9

Dependent Claim 68 words

The helical antenna of claim 7 in which first and second switch means, in changing from said first to said second discrete operating states, simultaneously reorient matched loads located at remote ends of said central element to contact the terminal ends of said first and second pairs of helical conducting elements so as to prevent reflections of terminating electromagnetic waves back through said antenna toward said feed points.

Claim 10

Dependent Claim 191 words

The helical antenna of claim 6 in which said plurality of terminal segments of said conductor means interior of said central element connect, in series, to said source of electromagnetic energy through a variable phase shifting means and phase shifting means equipped with two settings of 0* and 180* phase shifts operative by said control circuit means to control the phase of said first and second pairs of electromagnetic waves relative to one another, said variable phase shifting means connecting, in series, between said condition means and said source of electromagnetic energy and operative to aid in selectively steering said figure-eight pattern of radiation, in said second discrete operating state, through selected azimuthal angles relative to the borehole axis, said first and second phase shifting means equipped with two settings of 0* and 180* phase shifts being connected in series between at least one helical element of each of said first and second pairs of helical elements and said source of electromagnetic energy and operative to shift the polarizing mode of said first and second pairs of electromagnetic waves propagating along said antenna from a first to a second polarizing mode.

Claim 11

Dependent Claim 21 words

The helical antenna of claim 9 in which said first polarizing mode is vertical and said second polarizing mode is horizontal.

Claim 12

Independent Claim 269 words

The method of irradiating an earth formation penetrated by a borehole with a two-condition, selectively variable, pattern of electromagnetic energy whereby the distance and direction of an electromagnetic discontinuity within said formation, from said borehole, can be indicated and identified, comprising the steps of: in a transmitting mode, coupling electromagnetic energy from a source of energy to N pair(s) of helical conductors and a central cylindrical element coextensive with said helical conductors at a subset of feed points to propagate N pair(s) of electromagnetic waves in coextensive relationship along and radiating from said conductors into said formation, each of said waves being specified in terms of voltages existing between the helical conductors and the central cylindrical element and of currents carried by the helical conducting elements and by said cylindrical element, where N is any whole number greater than zero; directing said N pair(s) of electromagnetic waves in helical paths of common angular direction about said cylindrical element toward N remote end(s) of said cylindrical element; controlling, in a first discrete operating state, the direction of current phasers of said N pair(s) of electromagnetic waves as a function of the symmetrical poSition of said waves as measured along said antenna to irradiate electromagnetic energy into said earth formation which is omnidirectional in planes transverse to the axis of the borehole; in a second discrete operating state, reversing the axial direction of travel of current phasers of N waves of said N pair(s) of coextensively propagating electromagnetic waves and thereafter controlling said reversed current phasers so as to irradiate into said formation a highly directional, in azimuth figure-eight radiation pattern.

Claim 13

Independent Claim 269 words

The method of irradiating an earth formation penetrated by a borehole with a two-condition, selectively variable, pattern of electromagnetic energy whereby the distance and direction of an electromagnetic discontinuity within said formation, from said borehole, can be indicated and identified, comprising the steps of: in a transmitting mode, coupling electromagnetic energy from a source of energy to N pair(s) of helical conductors and a central cylindrical element coextensive with said helical conductors at a subset of feed points to propagate N pair(s) of electromagnetic waves in coextensive relationship along and radiating from said conductors into said formation, each of said waves being specified in terms of voltages existing between the helical conductors and the central cylindrical element and of currents carried by the helical conducting elements and by said cylindrical element, where N is any whole number greater than zero; directing said N pair(s) of electromagnetic waves in helical paths of common angular direction about said cylindrical element toward N remote end(s) of said cylindrical element; controlling, in a first discrete operating state, the direction of current phasers of said N pair(s) of electromagnetic waves as a function of the symmetrical poSition of said waves as measured along said antenna to irradiate electromagnetic energy into said earth formation which is omnidirectional in planes transverse to the axis of the borehole; in a second discrete operating state, reversing the axial direction of travel of current phasers of N waves of said N pair(s) of coextensively propagating electromagnetic waves and thereafter controlling said reversed current phasers so as to irradiate into said formation a highly directional, in azimuth figure-eight radiation pattern.

Claim 14

Dependent Claim 70 words

The method as in claim 11 in which N 1 whereby one pair of electromagnetic waves is generated between one pair of helical conducting elements and said central element and, in said first discrete operating state, propagate along said central element in a common axial direction, but, in said second discrete operating state, said waves of said one pair of waves propagate in opposite axial directions along said central element.

Claim 15

Dependent Claim 152 words

A method as in claim 11 in which N 2 whereby first and second pairs of electromagnetic waves are generated between first and second pairs of helical conducting elements and said central element, is said first discrete operating state, each pair of electromagnetic waves begin approximately at the midplane of said central element and coextensively propagate in the same axial direction toward a common end of said central element to generate said omnidirectional transverse radiation pattern in said formation, said first pair propagating in an opposite axial direction as said second pair of waves, in said second discrete state, an individual electromagnetic wave of each of said first and second pairs of electromagnetic waves propagates in coextensive relationship with another individual wave of the same pair of waves but in an opposite axial direction as said another wave so as to irradiate said formation with said directional, figure-eight pattern of electromagnetic radiation.

Claim 16

Dependent Claim 71 words

A method as in claim 11 in which the steps of reversing the direction of current phasers and then controlling the reversed current phasers to provide a highly directional, figure-eight pattern of radiation in azimuth are further characterized by the additional step of steering said figure-eight radiation pattern through selected azimuthal angles relative to the axis of borehole to isolate the azimuthal direction of said discontinuity relative to said borehole axis.

Claim 17

Dependent Claim 55 words

A method in accordance with claim 13 with the additional step of switching polarizing mode of said first and second pairs of electromagnetic waves from a first mode to a second polarizing mode and thereafter comparing signals received from a common discontinuity in each polarizing mode so as to indicate textural nature of said discontinuity.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-06-07	1974-12-07	1975-06-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-06-07	1978-12-07	1979-06-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-06-07	1982-12-07	1983-06-08	$7700.00	Window Closed / Lapsed

Elements for steering the beam of helical antenna for use in a borehole penetrating an earth formation

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