US3582766A — Passively controlled duplexer-coupler applied to …

Claim 1

Independent Claim 351 words

In a subsurface earth formation exploration tool for logging an earth formation penetrated by a borehole to approximate the distance to an electromagnetic discontinuity in said formation from said borehole, a helical antenna for irradiating said formation with electromagnetic radiation uniformly and transverse to the axis of said borehole in one polarizing mode and receiving, with maximum receiving sensitivity, reflections of said radiation in another polarizing mode other than that of said one polarizing mode, comprising: a. a central conductor element axially elongated along the axis of said borehole; b. first and second pairs of helically conducting elements wound axially along and radially spaced outwardly from said central element; c. each of said first and second pairs of helical conducting elements defining a coextensive pair of helical elements beginning substantially at the midplane of said cylindrical element, and each helical element of said coextensive pair winding in the same circumferential direction about said central element toward the same end of said central element as the other of said coextensive pair; and d. duplexer-coupler means positioned adjacent to the midplane of said central element interior of said central element for coupling energy between said central element and said first and second pairs of helical conducting elements, the feed points for each element being selected, in the transmitting mode, to produce first and second pairs of electromagnetic waves, one pair of said pairs of waves propagating in phase in an opposite axial direction from and radiating in phase with said other pair of waves in planes substantially transverse to the axis of said borehole to produce a uniform resultant transverse radiation pattern in the formation penetrated by said borehole, said radiation being in a first polarizing mode, said duplexer-coupler means including power-dependent switch means passively operative, in the receiving mode, to deactivate one helical element of each coextensive pair of helical elements so as to support the propagation of first and second reflected electromagnetic waves therealong whereby antenna sensitivity, in the receiving mode, for receiving reflected radiation is maximum for reflected radiation of another polarizing mode as that produced in said transmitting mode.

Claim 2

Dependent Claim 351 words

In a subsurface earth formation exploration tool for logging an earth formation penetrated by a borehole to approximate the distance to an electromagnetic discontinuity in said formation from said borehole, a helical antenna for irradiating said formation with electromagnetic radiation uniformly and transverse to the axis of said borehole in one polarizing mode and receiving, with maximum receiving sensitivity, reflections of said radiation in another polarizing mode other than that of said one polarizing mode, comprising: a. a central conductor element axially elongated along the axis of said borehole; b. first and second pairs of helically conducting elements wound axially along and radially spaced outwardly from said central element; c. each of said first and second pairs of helical conducting elements defining a coextensive pair of helical elements beginning substantially at the midplane of said cylindrical element, and each helical element of said coextensive pair winding in the same circumferential direction about said central element toward the same end of said central element as the other of said coextensive pair; and d. duplexer-coupler means positioned adjacent to the midplane of said central element interior of said central element for coupling energy between said central element and said first and second pairs of helical conducting elements, the feed points for each element being selected, in the transmitting mode, to produce first and second pairs of electromagnetic waves, one pair of said pairs of waves propagating in phase in an opposite axial direction from and radiating in phase with said other pair of waves in planes substantially transverse to the axis of said borehole to produce a uniform resultant transverse radiation pattern in the formation penetrated by said borehole, said radiation being in a first polarizing mode, said duplexer-coupler means including power-dependent switch means passively operative, in the receiving mode, to deactivate one helical element of each coextensive pair of helical elements so as to support the propagation of first and second reflected electromagnetic waves therealong whereby antenna sensitivity, in the receiving mode, for receiving reflected radiation is maximum for reflected radiation of another polarizing mode as that produced in said transmitting mode.

Claim 3

Dependent Claim 87 words

The helical antenna of claim 1 which (i) said first and second pairs of electromagnetic waves, in the transmitting mode, interact as a function of axial position along said antenna measured with respect to said midplane of said central element so as to generate vertically polarized radiation, and (ii) further, said power-dependent switch means passively operate, in the receiving mode, to deactivate said one helical element of said coextensive pair of helical elements so as to generate an antenna receiving sensitivity maximum for horizontally polarized, reflected radiation.

Claim 4

Dependent Claim 186 words

The antenna of claim 2 in which said duplexer-coupler means includes a series of segmented conductor means positioned interior of said central element, said series of segmented conductor means joined together in parallel at at least four separate junctions terminating in at least four terminal segments connected to the four feed points of said first and second pairs of helical elements, one of said series of segmented conductor means capable of being connected in series with a source of electromagnetic energy, uphole from the antenna; another of said series of segmented conductor means capable of being connected in series with a receiving means uphole from the antenna, remaining segments of said segmented conductor means having selected electrical lengths formed between said junctions such as to couple, in the transmitting mode, electromagnetic energy from said one segment of said series of segmented conductor means to at least said four terminal segments so as to generate said first and second pairs of electromagnetic waves along said antenna, while simultaneously isolating said other segment of said series of segmented conductor means from the damaging effects of said transmitted energy.

Claim 5

Dependent Claim 99 words

The helical antenna of claim 3 in which said four feed points for said first and second pairs of helical elements lie in a common plane and define corners of an imaginary, axially extending rectangle, the diagonally located feed points thereof forming first and second sets of feed points for said first and second pairs of helical elements, said series of segmented conductor means having selected electrical lengths, at least as measured between said four junctions, so as to couple, in opposite phase, energy at said first set of feed points relative to said second set of feed points.

Claim 6

Dependent Claim 84 words

The helical antenna of claim 4 in which said power-dependent switch means passively operated, in the receiving mode, to deactivate one helical element of each first and second pair of helical elements, are positioned in series with two of said terminal segments of said series of segmented conductor means, said two terminal segments being those segments which terminate in feed points which lie along the short side of said imaginary rectangle defining said feed points for said first and second pairs of helical elements.

Claim 7

Independent Claim 399 words

The method of irradiating an earth formation penetrated by a borehole with electromagnetic energy in one polarizing mode and receiving, with maximum sensitivity, reflections of said energy in another polarizing mode to that generated, whereby the distance to an electromagnetic discontinuity in said formation from said borehole can be approximated and the texture of said discontinuity identified, comprising the steps of: in a transmitting mode, coupling electromagnetic energy from a source of energy to first and second pairs of helical conductors and a central cylindrical element coextensive with said helical conductors at a series of feed points near a midportion of said cylindrical element to propagate first and second pairs of electromagnetic waves 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; directing said first pair of electromagnetic waves in helical paths of common angular direction about said cylindrical element from said midportion of said cylindrical element toward a remote end of said cylindrical element; directing said second pair of electromagnetic waves in helical paths in an angular direction common to said first pair of waves about said cylindrical element from said midportion of said cylindrical element in an axial direction opposed to that of said first pair of waves, each of said first and second pairs of electromagnetic waves having equal phases as a linear function of the position of said each pair of waves along said conductors in a direction away from said coupling points so as to increase radiation per unit length along said antenna; and controlling the phase of current of said first and second pairs of electromagnetic waves as a function of the symmetrical position of said waves as measured along said central element in opposite but equal axial directions from said coupling points to radiate electromagnetic radiation polarized in a first polarizing mode into said formation, in a receiving mode, passively decoupling one helical conductor of each of said first and second pairs of helical conductors based on the power level of the received energy so as to maximize receiving sensitivity of the antenna to energy having another polarizing mode as that of said radiated energy, whereby cross-polarized signals from discontinuities within said formation can be indicated and displayed.

Claim 8

Independent Claim 399 words

The method of irradiating an earth formation penetrated by a borehole with electromagnetic energy in one polarizing mode and receiving, with maximum sensitivity, reflections of said energy in another polarizing mode to that generated, whereby the distance to an electromagnetic discontinuity in said formation from said borehole can be approximated and the texture of said discontinuity identified, comprising the steps of: in a transmitting mode, coupling electromagnetic energy from a source of energy to first and second pairs of helical conductors and a central cylindrical element coextensive with said helical conductors at a series of feed points near a midportion of said cylindrical element to propagate first and second pairs of electromagnetic waves 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; directing said first pair of electromagnetic waves in helical paths of common angular direction about said cylindrical element from said midportion of said cylindrical element toward a remote end of said cylindrical element; directing said second pair of electromagnetic waves in helical paths in an angular direction common to said first pair of waves about said cylindrical element from said midportion of said cylindrical element in an axial direction opposed to that of said first pair of waves, each of said first and second pairs of electromagnetic waves having equal phases as a linear function of the position of said each pair of waves along said conductors in a direction away from said coupling points so as to increase radiation per unit length along said antenna; and controlling the phase of current of said first and second pairs of electromagnetic waves as a function of the symmetrical position of said waves as measured along said central element in opposite but equal axial directions from said coupling points to radiate electromagnetic radiation polarized in a first polarizing mode into said formation, in a receiving mode, passively decoupling one helical conductor of each of said first and second pairs of helical conductors based on the power level of the received energy so as to maximize receiving sensitivity of the antenna to energy having another polarizing mode as that of said radiated energy, whereby cross-polarized signals from discontinuities within said formation can be indicated and displayed.

Claim 9

Dependent Claim 138 words

A method as in claim 6 in which (i) the step of controlling the phase of the current of said first and second pairs of electromagnetic waves includes cancelling horizontal components of said current as a function of the symmetrical position of said first pair of waves relative to said second pair of waves as measured along said antenna in opposite but equal axial directions from said midportion of said central element so as to cause radiation of vertically polarized energy into said formation, said cancelled components of said current being located in planes perpendicular to the longitudinal axis of said central element and, further, (ii) the step of decoupling said one helical conductor of said first and second pairs of helical conductors, in said receiving mode, provides a receiving sensitivity that is maximum for horizontally polarized reflections.

Claim 10

Dependent Claim 122 words

The method as in claim 6 in which (i) the step of controlling the phase of the current of said first and second pairs of electromagnetic waves includes cancelling vertical components of the current as a function of symmetrical position of said waves in opposite but equal distances from said midportion of said central element so as to cause radiation of horizontally polarized energy into said formation, said cancelled components of the current being located in planes parallel to the longitudinal axis of said central element, and, further, (ii) the step of decoupling one helical conductor of each of said first and second pairs of helical conductors, in the receiving mode, provides a receiving sensitivity that is maximum for vertically polarized reflections.

Claim 11

Dependent Claim 34 words

A method in accordance with claim 6 with the additional step of comparing said cross-polarized signals with like-polarized generated and received signals from common discontinuities so as to indicate the texture of said discontinuity.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-05-31	1974-11-30	1975-06-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-05-31	1978-11-30	1979-06-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-05-31	1982-11-30	1983-06-01	$7700.00	Window Closed / Lapsed

Passively controlled duplexer-coupler applied to a helical antenna for use in a borehole penetrating an earth formation

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag