CN109922752B

CN109922752B - Electromagnetic navigation antenna assembly and electromagnetic navigation system including the same

Info

Publication number: CN109922752B
Application number: CN201780067029.3A
Authority: CN
Inventors: S·M·摩根; L·A·科伊拉克
Original assignee: Covidien LP
Current assignee: Covidien LP
Priority date: 2016-10-28
Filing date: 2017-10-26
Publication date: 2022-09-16
Anticipated expiration: 2037-10-26
Also published as: JP2020195159A; EP3531952A4; JP7018488B2; WO2018081344A2; AU2017348101B2; CN109922752A; JP2020502860A; JP2020195160A; WO2018081344A3; EP3531952A2; AU2017348101A1; JP7074813B2

Abstract

The present invention provides an antenna assembly for radiating at least one electromagnetic field for electromagnetic navigation, and an electromagnetic navigation system including such an antenna assembly. The antenna assembly includes a substrate and a planar antenna including traces deposited on the substrate and arranged in a plurality of loops. The respective distances between adjacent pairs of rings increase in a direction from the innermost ring to the outermost ring.

Description

Electromagnetic navigation antenna assembly and electromagnetic navigation system including the same

Background

Technical Field

The present disclosure relates to antenna assemblies for electromagnetic navigation and methods for designing such antenna assemblies. More particularly, the present disclosure relates to antenna assemblies for radiating electromagnetic fields for electromagnetic navigation, electromagnetic navigation systems including such antenna assemblies, and computer-implemented methods of designing such antenna assemblies.

RELATED ART

Electromagnetic (EM) navigation (EMN) helps expand medical imaging, diagnosis, prognosis, and treatment capabilities by enabling accurate determination of the position and/or orientation of a medical device while the device is located within a patient. One example of a medical procedure in which EMN is employed is the ELECTROMAGNETIC NAVIGATION

(ENB ^TM )(

(ENB ^TM ) Which includes a planning phase and a navigation phase. During the planning phase, a Computed Tomography (CT) scan of the patient's chest is used to generate a virtual three-dimensional bronchial map of the patient and a path for navigation phase planning. During the navigation phase, the antenna assembly radiates an electromagnetic field across the chest of the patient, the physician inserts an electromagnetic sensor that senses the radiated electromagnetic field into the airway of the patient, and the computing device determines a position and/or orientation (e.g., relative to the planned path) of the electromagnetic sensor based on characteristics of the sensed electromagnetic field.

To enable accurate determination of the position and/or orientation of the sensors, a detailed map of electromagnetic field measurements is generated at the location of the respective sensors. However, generating such a map requires accurate electromagnetic field measurements at many (e.g., thousands or more) locations within the expected electromagnetic volume, which is a laborious and time-consuming process that, in some cases, requires expensive machinery.

The burden of generating an electromagnetic field map is increased with the use of multiple antenna assemblies. For example, it may be desirable to employ small electromagnetic sensors, such as single coil electromagnetic sensors, in order to enable the electromagnetic sensors to reach deeper parts of the patient's body and/or remain in the body during subsequent medical procedures without interfering with additional medical equipment. However, to employ a small electromagnetic sensor for the EMN while maintaining the ability to determine multiple (e.g., six) degrees of freedom of the sensor, multiple antenna assemblies may be required to increase the number of electromagnetic fields of radiation to be sensed. In such cases, the extensive mapping procedure described above may need to be performed for each antenna assembly design. Furthermore, given the potential variations from manufacturing, it may even be necessary to complete the mapping procedure for each instance of a particular antenna assembly design (i.e., each individual antenna assembly manufactured).

In view of the foregoing, there is a need for improved electromagnetic navigation antenna assemblies and methods for designing such antenna assemblies.

Disclosure of Invention

According to one aspect of the present disclosure, an antenna assembly for radiating at least one electromagnetic field for electromagnetic navigation is provided. An antenna assembly includes a substrate and a planar antenna including a trace deposited on the substrate and arranged in a plurality of loops. The respective distances between adjacent pairs of rings increase in a direction from the innermost ring to the outermost ring.

In another aspect of the present disclosure, each of the rings includes a plurality of straight portions and a plurality of vertices. For example, in some aspects, each of the rings includes four straight portions and four vertices.

In further aspects of the disclosure, each of the vertices is disposed along one of four diagonals that bisect four respective vertices of the seed rectangle corresponding to the planar antenna.

In yet another aspect of the present disclosure, the antenna assembly further includes a connector having at least two terminals, and the trace has two ends coupled to the two terminals, respectively.

In another aspect of the present disclosure, an antenna assembly includes a plurality of planar antennas, and each of the plurality of planar antennas includes a respective trace deposited on a substrate and arranged in a respective set of loops. For each of the planar antennas, a respective distance between adjacent pairs of loops of the respective planar antenna increases in a direction from an innermost loop to an outermost loop.

In another aspect of the present disclosure, the substrate includes a plurality of layers and a planar antenna, and each of the plurality of planar antennas is deposited on a respective one of the layers.

In another aspect of the present disclosure, each of the planar antennas includes the same number of loops.

In another aspect of the present disclosure, each of the rings includes a plurality of straight portions and a plurality of vertices.

In another aspect of the present disclosure, the planar antennas have respective centroids relative to a plane of the substrate, the centroids being disposed in respective positions that are different from each other.

According to another aspect of the present disclosure, an electromagnetic navigation system is provided. The system includes an antenna assembly, an Alternating Current (AC) current driver to drive the antenna assembly, a catheter, an electromagnetic sensor, a processor, and a memory. An antenna assembly includes a substrate and a planar antenna and is configured to radiate an electromagnetic field. The planar antenna includes traces deposited on a substrate and arranged in a plurality of loops. The respective distances between adjacent pairs of rings increase in a direction from an innermost one of the rings to an outermost one of the rings. An electromagnetic sensor is fixed to the catheter and configured to receive a signal based on the radiated electromagnetic field. The memory includes instructions that, when executed by the processor, cause the processor to calculate a position and/or orientation of the electromagnetic sensor based on the received signals.

In another aspect of the present disclosure, an antenna assembly includes a plurality of planar antennas, each of the planar antennas including a respective trace deposited on a substrate and arranged in a respective set of loops. For each of the planar antennas, the respective distance between adjacent pairs of loops increases in a direction from an innermost one of the loops to an outermost one of the loops of the respective planar antenna.

In another aspect of the present disclosure, the substrate includes a plurality of layers, and each of the planar antennas is deposited on a respective layer of the plurality of layers.

In another aspect of the present disclosure, each of the loops of each of the planar antennas includes a plurality of straight portions and a plurality of vertices.

In another aspect of the present disclosure, the plurality of planar antennas each have a plurality of centroids with respect to the plane of the substrate, the centroids being disposed in respective positions different from each other.

According to another aspect of the present disclosure, an antenna assembly for radiating a plurality of electromagnetic fields for electromagnetic navigation is provided. The antenna assembly includes a substrate and a plurality of sets of planar antennas. The substrate includes a plurality of layers, and each of the planar antennas includes a respective trace deposited on a respective one of the plurality of layers and arranged in a respective number of loops. Each of the sets of planar antennas includes a first planar antenna, a second planar antenna, and a third planar antenna. For each of the groups of planar antennas: (1) the innermost loop of the first planar antenna has a first linear portion and a second linear portion, the second linear portion being substantially perpendicular to the first linear portion; (2) the innermost loop of the second planar antenna has a first linear portion and a second linear portion, the second linear portion being substantially perpendicular to the first linear portion and longer than the first linear portion; (3) the innermost loop of the third planar antenna has a first linear portion and a second linear portion, the second linear portion being substantially perpendicular to the first linear portion and longer than the first linear portion; (4) the first linear portion of the innermost loop of the second planar antenna is substantially parallel to the first linear portion of the innermost loop of the first planar antenna; and (5) the first linear portion of the innermost loop of the third planar antenna is substantially parallel to the second linear portion of the innermost loop of the first planar antenna.

In another aspect of the disclosure, for each of the planar antennas, a respective distance between adjacent ones of the plurality of loops increases in a direction from an innermost one of the plurality of loops to an outermost one of the plurality of loops.

In a further aspect of the disclosure, the respective innermost loops of each set of the first planar antennas are positioned on a respective layer of the plurality of layers at different respective angles from each other.

In yet another aspect of the disclosure, each of the plurality of rings includes a plurality of straight portions and a plurality of vertices.

In another aspect of the disclosure, for each planar antenna of the plurality of planar antennas, each of the plurality of vertices is disposed along one of four diagonals bisecting four respective vertices of the seed rectangle corresponding to the respective planar antenna of the plurality of planar antennas.

In a further aspect of the disclosure, respective outermost vertices of the plurality of planar antennas are no more than a predetermined threshold from the edge of the substrate.

In yet another aspect of the present disclosure, the planar antennas have respective centroids relative to a plane of the substrate, the centroids being different from one another.

In a further aspect of the disclosure, the number of groups of planar antennas is at least three.

In yet another aspect of the present disclosure, the antenna assembly further includes a connector having a plurality of terminals, and each of the respective traces of the plurality of planar antennas is coupled to a respective terminal of the plurality of terminals.

According to another aspect of the present disclosure, an electromagnetic navigation system is provided that includes an antenna assembly, a catheter, an electromagnetic sensor, a processor, and a memory. The antenna assembly is configured to radiate an electromagnetic field and includes a substrate and a plurality of sets of planar antennas. The substrate includes a plurality of layers, and each of the planar antennas includes a respective trace deposited on a respective one of the plurality of layers and arranged in a respective number of loops. Each of the sets of planar antennas includes a first planar antenna, a second planar antenna, and a third planar antenna. For each of the plurality of sets of planar antennas: (1) the innermost loop of the first planar antenna has a first linear portion and a second linear portion, the second linear portion being substantially perpendicular to the first linear portion; (2) the innermost loop of the second planar antenna has a first linear portion and a second linear portion, the second linear portion being substantially perpendicular to the first linear portion and longer than the first linear portion; (3) the innermost loop of the third planar antenna has a first linear portion and a second linear portion, the second linear portion being substantially perpendicular to the first linear portion and longer than the first linear portion; (4) the first linear portion of the innermost loop of the second planar antenna is substantially parallel to the first linear portion of the innermost loop of the first planar antenna; and (5) the first linear portion of the innermost loop of the third planar antenna is substantially parallel to the second linear portion of the innermost loop of the first planar antenna. An electromagnetic sensor is fixed to the catheter and configured to receive one or more signals based on the radiated electromagnetic field. The memory includes instructions that, when executed by the processor, cause the processor to calculate a position and/or orientation of the electromagnetic sensor based on the received signals.

In a further aspect of the disclosure, the respective innermost loops of each group of the first planar antennas are positioned at different respective angles from each other on a respective layer of the plurality of layers.

In yet another aspect of the present disclosure, the plurality of planar antennas have a plurality of respective centroids relative to the plane of the substrate, the centroids being different from one another.

In yet another aspect of the present disclosure, the electromagnetic navigation system further includes a connector having a plurality of terminals, and each of the respective traces of the plurality of planar antennas is coupled to a respective terminal of the plurality of terminals.

According to another aspect of the present disclosure, a computer-implemented method of designing an antenna assembly for radiating an electromagnetic field for electromagnetic navigation is provided. The method includes calculating a plurality of diagonal lines, respectively, with respect to a coordinate system of a substrate having a boundary based on a seed rectangle having a plurality of vertices. The plurality of diagonals respectively bisect the plurality of vertices of the seed rectangle and extend from the plurality of vertices of the seed rectangle to the boundary. For each of the plurality of diagonals, the method further comprises: (1) determining a plurality of distances between pairs of vertices of the plurality of adjacent planar antennas to be positioned along respective diagonals, respectively, wherein the plurality of distances increase in a direction from the respective vertices to the boundary of the seed rectangle; and (2) positioning the planar antenna vertices along the respective diagonals based on the determined plurality of distances. The planar antenna layout is generated by interconnecting planar antenna vertices via respective straight portions to form a plurality of loops that sequentially traverse each of a plurality of diagonal lines.

In another aspect of the disclosure, a plurality of distances is determined based at least in part on a predetermined number of loops of the planar antenna.

In further aspects of the disclosure, the plurality of distances is determined based at least in part on a predetermined minimum spacing between adjacent vertices and/or a predetermined minimum spacing between adjacent traces.

In yet another aspect of the disclosure, the substrate has a plurality of layers and the method further includes generating a plurality of planar antenna layouts corresponding to the plurality of layers, respectively.

In another aspect of the disclosure, the computer-implemented method further includes adding a plurality of straight portions to the planar antenna layout, the straight portions routed from at least two of the planar antenna vertices to the connector locations with reference to a coordinate system of the substrate.

In further aspects of the disclosure, the computer-implemented method further includes calculating, for each of the plurality of diagonals, a layout distance between a respective vertex of the seed rectangle and a boundary along the respective diagonal, and determining a plurality of distances between pairs of neighboring planar antenna vertices, respectively, based at least in part on the calculated layout distances.

In yet another aspect of the disclosure, each of the plurality of loops includes a plurality of the straight portions and a plurality of the planar antenna vertices.

In another aspect of the present disclosure, an outermost planar antenna vertex of the plurality of planar antenna vertices is no more than a predetermined threshold distance from a boundary of the substrate.

In further aspects of the disclosure, the computer-implemented method further includes exporting data corresponding to the generated planar antenna layout to a circuit board routing tool and/or a circuit board manufacturing tool.

In yet another aspect of the disclosure, the computer-implemented method further includes exporting data corresponding to the generated planar antenna layout to an electromagnetic simulation tool, and simulating an electromagnetic field based on a superposition of the plurality of electromagnetic field components from the plurality of straight portions of the planar antenna layout, respectively, based on the exported data.

According to another aspect of the present disclosure, a non-transitory computer-readable medium is provided that stores instructions that, when executed by a processor, cause the processor to perform a method of designing an antenna assembly for radiating an electromagnetic field for electromagnetic navigation. The method includes calculating a plurality of diagonal lines, respectively, with respect to a coordinate system of a substrate having a boundary based on a seed rectangle having a plurality of vertices. The plurality of diagonals respectively bisect the plurality of vertices of the seed rectangle and extend from the plurality of vertices of the seed rectangle to the boundary. For each of the plurality of diagonals, the method further comprises: (1) determining a plurality of respective distances between a plurality of adjacent pairs of planar antenna vertices to be located along respective diagonals; and (2) positioning the planar antenna vertices along the respective diagonals based on the determined plurality of distances. The plurality of distances increases in a direction from the respective vertex to the boundary of the respective seed rectangle. The planar antenna layout is generated by interconnecting planar antenna vertices via respective straight portions to form a plurality of loops that sequentially traverse each of a plurality of diagonal lines.

In another aspect of the disclosure, the method further includes adding a plurality of straight portions to the planar antenna layout, the straight portions routed from at least two of the planar antenna vertices to the connector locations with reference to a coordinate system of the substrate.

In a further aspect of the disclosure, the method further includes calculating, for each of the plurality of diagonals, a layout distance between a respective vertex of the seed rectangle and a boundary along the respective diagonal, and determining a plurality of distances between pairs of vertices of the plurality of adjacent planar antennas, respectively, based at least in part on the calculated layout distances.

In yet another aspect of the present disclosure, each of the plurality of loops includes a plurality of straight portions and a plurality of planar antenna vertices.

In a further aspect of the disclosure, the method further comprises exporting data corresponding to the generated planar antenna layout to a circuit board routing tool and/or a circuit board manufacturing tool.

In yet another aspect of the disclosure, the method further includes exporting data corresponding to the generated planar antenna layout to an electromagnetic simulation tool, and simulating an electromagnetic field based on a superposition of a plurality of electromagnetic field components from a plurality of linear portions, respectively, of the planar antenna layout based on the exported data.

Any of the above aspects and embodiments of the present disclosure may be combined without departing from the scope of the present disclosure.

Drawings

This patent or application document contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the office upon request and payment of the necessary fee.

Objects and features of the disclosed systems and methods will become apparent to those of ordinary skill in the art upon reading the description of the various embodiments with reference to the drawings, in which:

FIG. 1 is a perspective view of an exemplary electromagnetic navigation (EMN) system according to one embodiment of the present disclosure;

fig. 2 shows an exemplary design of an antenna assembly of an EMN system according to one embodiment of the present disclosure;

fig. 3 is a flow diagram illustrating an exemplary procedure for designing an antenna assembly according to one embodiment of the present disclosure;

fig. 4-11 are exemplary graphical representations of certain aspects of the procedure of fig. 3, according to one embodiment of the present disclosure;

FIG. 12 is an illustration of a plurality of exemplary antennas according to one embodiment of the present disclosure, which may be designed according to the procedure of FIG. 3;

FIG. 13 shows an exemplary design of a loop antenna layout trace arrangement according to one embodiment of the present disclosure; and is

Fig. 14 is a block diagram of an exemplary computing device for use in various embodiments of the present disclosure.

Detailed Description

The present disclosure relates to antenna assemblies for radiating electromagnetic fields for electromagnetic navigation, electromagnetic navigation systems including such antenna assemblies, and computer-implemented methods of designing such antenna assemblies. In one example, due to geometric and other aspects of the antenna assemblies herein, the need to generate and employ detailed electromagnetic field maps may be avoided by instead enabling electromagnetic field maps that are theoretically calculated based on characteristics of the antenna assemblies to be employed either alone or in combination with more readily generated, low-density electromagnetic field maps derived from measurements. In other words, the antenna assemblies herein may be used as a basis for EMN generation of accurate high-density theoretical electromagnetic field maps without having to use expensive measurement equipment and without having to perform time-consuming and labor-intensive measurements.

In another example, the antenna assemblies herein include multiple planar antennas on a single substrate with characteristics (such as different geometries and/or relative positions from one another) that enable multiple (e.g., six) degrees of freedom of a small electromagnetic sensor (such as a single coil sensor) to be determined.

In yet another example, an antenna assembly herein includes traces deposited on a layer of a substrate and forming a plurality of loops, wherein spacing between the loops and spacing from a boundary or edge of the substrate enables efficient use of the usable area of the substrate.

In further examples, provided herein are automated or semi-automated highly reproducible computer-implemented methods for designing antenna assemblies. The antenna assembly design generated in this manner can be exported into a Printed Circuit Board (PCB) layout software tool to minimize the need for extensive manual layout. The antenna assembly design may also be exported into an electromagnetic field simulator software tool to enable generation of a theoretical electromagnetic field map of the antenna assembly.

Specific embodiments of antenna assemblies, systems including such antenna assemblies, and methods of designing the antenna assemblies are described herein. However, these specific embodiments are merely exemplary of the disclosure, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for enabling one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Although the exemplary embodiments described below relate to bronchoscopy of a patient's airway, those skilled in the art will recognize that the same or similar components, systems, and methods may also be used with other luminal networks, such as vascular networks, lymphatic networks, and/or gastrointestinal networks.

Fig. 1 illustrates an exemplary electromagnetic navigation (EMN) system 100 provided in accordance with the present disclosure. Generally, EMN system 100 is configured to identify, among other things, a position and/or orientation of a medical device being navigated toward a target location within a patient's body by using an antenna assembly that generates one or more electromagnetic fields sensed by a sensor secured to the medical device. In some cases, EMN system 100 is further configured to enhance Computed Tomography (CT) images, Magnetic Resonance Imaging (MRI) images, and/or fluoroscopic images employed during navigation of the medical device through the patient's body toward an object of interest, such as a dead portion in a network of lumens in the patient's lungs.

EMN system 100 includes catheter guidance assembly 110, bronchoscope 115, computing device 120, monitoring device 130, patient platform 140 (which may be referred to as an EM pad), tracking device 160, and reference sensor 170. Bronchoscope 115 is operatively coupled to computing device 120 (via tracking device 160) and monitoring device 130 via respective wired (as shown in fig. 1) or wireless connections (not shown in fig. 1).

During the navigation phase of the EMN bronchoscopy procedure, bronchoscope 115 is inserted into the mouth of patient 150 and images of the luminal network of the lungs are captured. Catheter guidance assembly 110 is inserted into bronchoscope 115 to access the periphery of the luminal network of the lungs of patient 150. The catheter guide assembly 110 may include a catheter or an Elongated Working Channel (EWC)111, with an EM sensor 112 secured to a portion (e.g., a distal portion) of the EWC 111. A positionable guide catheter (LG) may be inserted into the EWC111 with another EM sensor (not shown in fig. 1) secured to a portion (e.g., a distal portion) of the LG. The EM sensor 112 fixed to the EWC111 or the EM sensor fixed to the LG is configured to receive signals based on the electromagnetic field radiated by the antenna assembly 145 and, based on the received signals, for determining the position and/or orientation of the EWC111 or LG during navigation through the network of cellular lumens of the lungs. Due to size limitations of the EM sensor 112 relative to the EWC111 or LG, in some cases the EM sensor 112 may include only a single coil for receiving one or more EM signals generated by the antenna assembly 145, as described in more detail below. However, the number of coils in the EM sensor 112 is not limited to one, but may be two, three, or more.

Computing device 120 (such as a laptop, desktop, tablet, or other suitable computing device) includes a display 122, one or more processors 124, one or more memories 126, an AC current driver 127 for providing an AC current signal to an antenna assembly 145, a network interface controller 128, and one or more input devices 129. The particular configuration of computing device 120 shown in fig. 1 is provided as an example, but other configurations of the components shown in fig. 1 included in computing device 120 are also contemplated. In particular, in some embodiments, one or more of the components (122, 124, 126, 127, 128, and/or 129) included in computing device 120 shown in fig. 1 may alternatively be separate from computing device 120 and may be coupled to computing device 120 and/or to any other component of system 100 by one or more respective wired or wireless paths to facilitate transmission of power and/or data signals throughout system 100. For example, although not shown in fig. 1, AC current driver 127 may be separate from computing device 120 in some exemplary aspects and may be coupled to antenna assembly 145 by one or more respective paths and/or to one or more components of computing device 120, such as processor 124 and memory 126.

In some aspects, EMN system 100 may also include a plurality of computing devices 120, wherein the plurality of computing devices 120 are employed to plan, process, visualize, or otherwise assist a clinician in a manner suitable for a medical procedure. The display 122 may be touch-sensitive and/or voice-activated, enabling the display 122 to function as both an input device and an output device. The display 122 may display a two-dimensional (2D) image or a three-dimensional (3D) image, such as a 3D model of the lungs, to enable a physician to locate and identify a portion of the lungs showing symptoms of a pulmonary disease.

The one or more memories 126 store one or more programs and/or computer-executable instructions that, when executed by the one or more processors 124, may cause the one or more processors 124 to perform various functions and/or procedures. For example, the processor 124 may calculate the position and/or orientation of the EM sensor 112 based on the electromagnetic signals radiated by the antenna assembly 145 and received by the EM sensor 112. The processor 124 may also perform image processing functions to cause a 3D model of the lungs to be displayed on the display 122. The processor 124 may also generate one or more electromagnetic signals to be radiated by the antenna assembly 145. In some embodiments, computing device 120 may also include a separate graphics accelerator (not shown in fig. 1) that performs only image processing functions, so that one or more processors 124 are available to other programs. The one or more memories 126 also store data, such as mapping data for EMNs, image data, medical record data for patients, prescription data, and/or data related to patient disease history, and/or other types of data.

The mapping data may link a plurality of grid points in a coordinate system of an EM volume in which a medical device (e.g., EWC111, LG, a therapy probe, or another surgical device) is navigated to EM signal characteristics (e.g., signal strengths) corresponding to the grid points, respectively. As such, when the EM sensor 112 senses EM signals having certain characteristics at particular grid points, the one or more processors 124 may compare the sensed EM signal characteristics to EM signal characteristics in the mapping data and determine the location and/or orientation of the EM sensor 112 in the EM volume based on the results of the comparison.

As shown in fig. 1, the platform 140 is configured to provide a flat surface on which the patient 150 lies during the EMN navigation procedure. An antenna assembly 145 (which may also be referred to as an EM field generating device) is disposed on the platform 140 or included as a component of the platform 140. The antenna assembly 145 includes one or more antennas, such as a planar loop antenna (not shown in fig. 1). Exemplary aspects of the antenna assembly 145 are described in further detail below.

With patient 150 lying on platform 140, one or more processors 124 (or another signal generator not shown in fig. 1) generate and provide one or more AC current signals to the antenna of antenna assembly 145 through AC current driver 127, which are converted by the antenna into one or more corresponding EM signals and radiated in a manner sufficient to surround a portion of patient 150. In some aspects, the antenna assembly 145 includes a connector having at least two terminals, and the traces of the antenna (not shown in fig. 1) have two ends coupled to the two connector terminals, respectively, to form a signal communication path from the one or more processors 145 to the antenna.

Having described an exemplary EMN system 100, reference will now be made to fig. 2, which is an illustration of an exemplary antenna assembly layout 200 of the antenna assembly 145 of the EMN system 100, according to one embodiment of the present disclosure. The antenna assembly layout 200 includes a substrate 210, such as a Printed Circuit Board (PCB), which is formed of an electrically insulating material and may include one or more layers. The antenna assembly layout 200 also includes a plurality of planar antennas 220, formed of conductive material (such as PCB traces), deposited on the substrate 210 and arranged in a plurality of loops or as coils. In one example, each of the planar antennas 220 is deposited on a respective one of the layers of the substrate 210. In the exemplary antenna assembly layout 200 of fig. 2, multiple layers of the substrate 210 are shown simultaneously.

Each of the plurality of antennas may be configured to radiate a separate EM field, for example using frequency and/or time division multiplexing controlled by processor 124 or by another generator. For example, the antenna may be configured in some aspects to radiate a number of EM fields of sufficient number and/or sufficient diversity in characteristics (such as frequency, time, modulation scheme, etc.) to enable a single coil electromagnetic sensor to be mounted on the EWC111 or any other medical device for determining the position and/or orientation of the sensor, EWC111, and/or medical device. The antenna assembly 145 may, for example, include six to nine or more loop antennas. In some embodiments, for each of the loop antennas, the distance between its adjacent loops increases as the loop becomes larger. For example, for each of the planar antennas, the respective distance between adjacent pairs of loops may increase in a direction from an innermost one of the loops to an outermost one of the loops of the respective planar antenna. In various embodiments, two or more of the loop antennas of the antenna assembly 145 may have the same number of loops, or may each have a different number of loops.

Having described an exemplary antenna assembly layout 200 for an antenna assembly 145 of an EMN system 100, reference will now be made to fig. 3, which is a flow diagram illustrating an exemplary procedure 300 for designing an antenna assembly (such as the antenna assembly 145) according to one embodiment of the present disclosure. In various embodiments, procedure 300 may be fully computer-implemented or partially computer-implemented. Reference will also be made to fig. 4-13, which are illustrations of certain steps of a procedure 300 according to one embodiment of the present disclosure. The exemplary method 300 of fig. 3 may be implemented to design an antenna assembly including one antenna or an antenna assembly including multiple antennas. For purposes of illustration, the present description of method 300 will be in the context of designing an antenna assembly that includes multiple antennas. However, while certain aspects of the method 300 will be described with respect to only a single one of the plurality of antennas, these aspects of the method 300 will be similarly applicable to the other ones of the plurality of antennas.

Before describing the details of the procedure 300, an overview of the procedure 300 will be provided. Generally speaking, according to procedure 300, the design of an antenna assembly is based on a set of design parameters and/or constraints, including the number of antennas M of the antenna assembly to be designed, and for each antenna of the antenna assembly, including the seed shape of the antenna, the location of the centroid of the seed shape on the substrate on which the antenna is to be fabricated, the number of loops (N) of the antenna, the minimum center-to-center spacing (TCCM) of the antenna trace, and the size of the edges or boundaries of the substrate. The location of the antenna vertex of the antenna is determined based on the seed shape. The antenna design then proceeds to interconnect the antenna vertices by straight portions, starting with the innermost antenna vertex and progressing to the outermost antenna vertex, such that the entire antenna forms a coil comprising a single trace arranged in a plurality of loops. In one aspect, each loop of the antenna assembly is generated from the seed shape toward a boundary of the substrate and effectively covers a majority of the available surface area of the seed shape exterior substrate layer. Both ends of the trace are routed to connector locations to enable the antenna to be coupled to a signal generator.

For antenna assemblies having multiple planar antennas on respective layers of a multilayer substrate, the general procedure is repeated for each of the antennas. In addition, data corresponding to the designed antenna layout may be derived to an electromagnetic field simulation tool for simulating the electromagnetic field that the respective antenna should generate based on its particular characteristics (e.g., the theoretical electromagnetic field mapping of EMN described above). Data corresponding to the designed antenna layout may also be exported to a PCB manufacturing tool to enable the antenna assembly to be manufactured in an automated manner according to the designed antenna layout.

Before describing the details of the procedure 300, an example seed shape and its characteristics will be described with reference to fig. 4. Specifically, fig. 4 shows an example of nine seed rectangles 401 to 409 of an antenna assembly to be designed according to procedure 300. Each of the seed rectangles 401 to 409 includes four vertices within the edge 400 of the substrate. The number of seed rectangles shown in the example of fig. 4 is nine, and thus the number of antennas M, but this is for illustrative purposes only and should not be considered limiting. In other embodiments, the number of seed shapes may be, for example, six, nine, or more, and thus the number of antennas M may also be so. As one example, the square 400 may represent an edge of the substrate, while a boundary (not shown in fig. 4) representing an area of the substrate available for placement of antennas may be formed by a square in the x-z plane that is contained within the edge 400 of the substrate and that is smaller than the edge 400 of the substrate by some predetermined threshold or amount of buffering.

In another example, the antenna assemblies herein include multiple planar antennas having characteristics (such as different geometries and/or relative positions from one another) on a single substrate (e.g., on respective layers of a multilayer substrate) that enable multiple (e.g., six) degrees of freedom of a small electromagnetic sensor (such as a single coil sensor) to be determined. For example, as shown in FIG. 4, the nine seed rectangles 401-409 may be divided into three groups, with the seed rectangles 401-403 in the first group; seed rectangles 404 through 406 are in the second group; and the seed rectangles 407-409 are in a third group. As shown in fig. 4, the three seed rectangles in each set have a particular geometric relationship with respect to each other. For example, one seed rectangle is square (or substantially square-like) and the other two seed rectangles are non-square rectangles and are positioned near both sides of the square. For example, the seed rectangle 401 is square, the seed rectangle 402 is located along the length of the seed rectangle 401, and the seed rectangle 403 is located along the width of the seed rectangle 401. In addition, the length of the seed rectangle 402 is longer than the width of the square 401 and is similar to the length of the seed rectangle 401, while the width of the seed rectangle 402 is smaller than the width of the square 401; and the width of the seeding rectangle 403 is longer than the length of the square 401 and is similar to the width of the square 401, while the length of the seeding rectangle 402 is less than the length of the square 401. The seed rectangles 404 to 406 of the second set and the seed rectangles 407 to 409 of the third set also have similar geometrical features as the seed rectangles 401 to 403 of the first set.

In other words, for each of the sets of planar antennas that may be generated based on the seed rectangles 401 through 409: the innermost loop (e.g., corresponding to the seed rectangle 401) of the first planar antenna has a first linear portion (e.g., first linear portion 410) and a second linear portion (e.g., second linear portion 411) that is substantially perpendicular to the first linear portion (e.g., first linear portion 410); the innermost loop of the second planar antenna (e.g., corresponding to the seed rectangle 402) has a first linear portion (e.g., first linear portion 412) and a second linear portion (e.g., second linear portion 413) that is substantially perpendicular to and longer than the first linear portion (e.g., first linear portion 412); the innermost loop (e.g., corresponding to the seed rectangle 403) of the third planar antenna has a first linear portion (e.g., first linear portion 414) and a second linear portion (e.g., second linear portion 415) that is substantially perpendicular to and longer than the first linear portion (e.g., first linear portion 414); a first linear portion (e.g., first linear portion 412) of the seed rectangle of the innermost loop of the second planar antenna is substantially parallel to a first linear portion (e.g., first linear portion 410) of the innermost loop of the first planar antenna; and a first linear portion (e.g., first linear portion 414) of an innermost loop of the third planar antenna is substantially parallel to a second linear portion (e.g., second linear portion 411) of an innermost loop of the first planar antenna. Although further reference numerals for the first and second linear portions of the seed rectangles 404 to 409 (and thus for the planar antenna) have been omitted in fig. 4 for clarity, the seed rectangles 404 to 406 of the second set and the seed rectangles 407 to 409 of the third set each have a similar geometrical relationship with respect to each other, as described above in the context of the seed rectangles 401 to 403 of the first set.

In one aspect, the three groups may be geometrically dispersed with each group in the substrate 210. The dispersion may be accomplished by geometric and/or angular relationships. For example, the respective innermost loops of the planar antennas of each group may be positioned at different respective angles from each other on the respective layers of the multilayer substrate. Additionally, the planar antenna and/or the seed rectangle upon which the planar antenna is based may have respective centroids (e.g., represented by dots in fig. 4) relative to the plane of the substrate that are different from one another. In addition, the outer boundary of the first set includes all of the seed rectangles 404 to 409 of the second and third sets. In addition, the seed rectangles 404 to 409 of the second and third sets are geometrically dispersed in the outer boundary of the first set.

In addition, each group has an angular relationship with respect to two axes (i.e., the x-axis and the z-axis). For example, the first set of seed rectangles 401 are coincident with the two axes, while the second set of seed rectangles 404 and the third set of seed rectangles 407 are angled at different angles with respect to the two axes, respectively. In other words, the minimum angle between the seed rectangle 401 or square of the first set and the x-axis is zero; the minimum angle between the seed rectangle 404 and the x-axis is greater than zero but less than the minimum angle between the seed rectangle 407 of the third set and the x-axis. However, the relationship between the three groups is not limited to geometric and angular relationships, but may be extended within the scope of the present disclosure in any manner readily apparent to one of ordinary skill in the art.

The four vertices of each of the seed rectangles 401 to 409 may be provided in coordinate form (x, z) in the x-z plane. In one aspect, the centroid of each of the seed rectangles 401 through 409 may also be provided in coordinate form or may be calculated from the four vertices. The dispersion may also be achieved by dispersing a centroid within the substrate 210. In one aspect, the centroids of all seed rectangles 401 to 409 are disposed at different positions from each other on the substrate.

Referring now to fig. 3, prior to block 301, a set of design parameters and/or constraints (e.g., the seed shape of the antenna, the location of the centroid of the seed shape on the substrate on which the antenna is to be fabricated, the number of loops (N) of the antenna, the minimum center-to-center spacing (TCCM) of the antenna traces, and the size of the edges or boundaries of the substrate) for a first antenna of an antenna assembly to be designed are set (not shown in fig. 3). For illustration purposes, the seed shape used in each antenna in procedure 300 is a seed rectangle; however, this should not be considered limiting. Other seed shapes (e.g., seed triangle, seed pentagon, seed hexagon, any convex polygon, convex curved shape (e.g., oval, egg, circle, etc.), or any other suitable seed shape) are contemplated and may be employed in procedure 300. In some embodiments, any combination of different seed shapes may be used for the antennas of the antenna assemblies, respectively. Each seed shape has a plurality of vertices. More specifically, each seed rectangle has four vertices.

At block 301, antenna index i is indexed _{Antenna with a shield} And (5) initializing. For example, i _{Antenna with a shield} A plurality of (M, where M is equal to 1) to correspond to the antenna component to be designed>1) A first one of the antennas. Antenna index i, as described below _{Antenna with a shield} The purpose of (a) is to enable procedure 300 to be repeated for each of the M antennas of an antenna assembly in the case of an antenna assembly that includes multiple antennas. For example, in some examples, the substrate has multiple layers (e.g., as in a multi-layer PCB) and the method 300 is employed to generate multiple planar antenna layouts corresponding to antennas to be deposited on corresponding layers in the multiple layers of the substrate.

At block 302, a plurality of diagonals are calculated relative to a coordinate system of the substrate based on the seed rectangle. Generally, the number of diagonals calculated at block 302 is equal to the number of vertices of the seed shape. Specifically, in the case of a seed rectangle having four vertices, four diagonals are calculated which bisect the four vertices of the seed rectangle, respectively, and extend from the four vertices of the seed rectangle to the boundaries of the substrate, respectively. The boundary of the substrate may be a physical boundary of the substrate, such as an edge of a PCB, or may be a theoretically applied boundary, such as a boundary offset from an edge of a PCB by a predetermined buffer distance.

In one example, as part of the computation of the plurality of diagonals performed at block 302, the origin of the diagonals for each of the vertices of the seed rectangle is first computed, and then the vertices of the innermost loop of the antenna (also referred to as seed vertices) are determined based on the seed rectangle. For example, FIG. 5 shows the

calculated origins

511 and 512 for the seed rectangle 405 of FIG. 4. The

origins

511 and 512 are defined by the four vertices 501-504 of the seed rectangle 405. In one aspect, one origin may correspond to a single vertex of the seed rectangle, or one origin may correspond to two adjacent vertices. In another aspect,

origins

511 and 512 may be positioned on the diagonals of the seed rectangle or on the diagonals that bisect the respective angles to form two 45 degree angles. In this case, the diagonal defines the position of the apex of the loop antenna. As one example, origin 511 is positioned on a diagonal that bisects the 90 degree angle at vertex 501 to form two 45 degree angles. Also as shown in FIG. 5, origin 511 is positioned at the intersection of the diagonals, which bisect the angles at

vertices

501 and 502. In the same manner, origin 512 is located at the intersection of the diagonals, which bisect the angles at

vertices

503 and 504. In one example, the origin of the diagonal of each vertex of the seed rectangle may be calculated by performing a Principal Component Analysis (PCA) on the coordinates of the four vertices 501 to 504 using singular value decomposition. The following notations are used herein:

P _jk represents the kth vertex of the jth ring, where j is 1 to N and k is 1 to 4;

P _jkx and P _jkz Respectively represent the vertexes P _jk X and z coordinates of (a);

{P _j1 、P _j2 、P _j3 、P _j4 or { P alone } _jk Is a 4 x 2 matrix with four vertices P of the jth ring _j1 、P _j2 、P _j3 、P _j4 As its row;

u represents a group having { P _jk }{P _jk } ^T As a 4 × 4 matrix of its columns;

v represents a group having { P } _jk } ^T {P _jk The orthogonal eigenvectors of the } as a 2 × 2 matrix of its columns; and is

S represents a 4 x 2 matrix whose non-zero elements are located only at its diagonal and are P _jk }{P _jk } ^T Or { P _jk } ^T {P _jk The square root of the eigenvalues of; and is

Representing a 4 x 2 matrix whose non-zero elements are located only at its diagonal and equal to the smallest non-zero element of S.

Given the ith seed momentFour vertices R of the shape _k (R _kx 、R _kz ) The centroid C (C) of the ith seed rectangle is calculated as follows _x 、C _z )：

By pair-subtracting four vertices R of the centroid _j The singular value decomposition is performed, and S, V and the D matrix are obtained as follows:

USV ^T ＝{R _k -C} (2)

wherein { R _k -C is a 4 × 2 matrix, { R } _k -C minus the vertex of the centroid (R) per action _kx -C _x 、R _kz -C _z ) And k is 1 to 4.

S is a diagonal line with only non-zero elements (i.e., S) ₁₁ And S ₂₂ ) 4 x 2 matrix. Based on singular value decomposition, S ₁₁ Is greater than or equal to S ₂₂ . By mixing S ₁₁ Is replaced by S ₂₂ By the value of (c), we can obtain a new 4 x 2 diagonal matrix

Wherein

And

is equal to S ₂₂ . The origin O of each vertex can then be obtained by _k ：

Because of the fact that

Is the minimum of the diagonal elements of S, so { O _k Includes only two negations corresponding to

origins

511 and 512 in the ith seed rectangleThe same row, as shown in fig. 5.

After obtaining the

origins

511 and 512, a first set of four seed vertices P in the ith seed rectangle is determined _1k . These first set of four seed vertices P _1k Is the seed vertex of the innermost loop of the respective antenna and can be used to determine other vertices of that antenna.

Given a minimum center-to-center spacing of Traces (TCCM) (which represents a predetermined minimum distance between traces or loops for a particular antenna or for all antennas of a particular antenna assembly), a first seed vertex P ₁₁ By adding R ₁ Move into its corresponding diagonal line, which bisects R towards the inside of the ith seed rectangle ₁ At a 90 degree angle. This can be done by first starting from R ₁ Two vectors are defined to accomplish:

wherein

Is a vector, from a corresponding origin O _k Point of direction R _k ，

Is from R ₁ Point of direction R ₄ A vector of (a) and

is from R ₁ Point of direction R ₂ The vector of (2). By mixing

Is added to the unit vector of

Obtaining a vector whose direction coincides with a corresponding diagonal, which diagonal will be at R ₁ The 90 degree angle of the point bisects to form two 45 degree angles, where the symbol "| | |" represents the magnitude of the vector inside the symbol "| | | |". Then, the first seed vertex P is obtained by the following formula ₁₁ ：

Wherein

Is derived from the corresponding origin O ₁ And thus represents P ₁₁ The coordinates of (a). FIG. 6 shows three other seed vertices P of the antenna ₁₂ 、P ₁₃ And P ₁₄ These seed vertices match R ₂ 、R ₃ And R ₄ 。P _1k And the minimum distance between the four sides of the ith seed rectangle is equal to TCCM. FIG. 7 shows a vector Diag ₁ 、Diag ₂ 、Diag ₃ And Diag ₄ These vectors may form respective portions of a diagonal line that bisects the seed vertex P ₁₁ 、P ₁₂ 、P ₁₃ And P ₁₄ And from the corresponding seed vertex P ₁₁ 、P ₁₂ 、P ₁₃ And P ₁₄ Extending to the boundary of the substrate.

Referring back to FIG. 3, at block 303 the diagonal index i is initialized _{Diagonal line} . For example, i _{Diagonal line} Is set equal to 1 to correspond to the first of the four diagonals of the seed rectangle. Diagonal index i, as described below _{Diagonal line} The purpose of (a) is to enable aspects of the procedure to be repeated for each of the diagonals of the seed rectangle.

At block 304, for the respective diagonal, a vertex-layout-distance (also referred to herein as a layout) between the respective vertex of the seed rectangle and a boundary of the substrate along the respective diagonal is calculatedDistance) V _{Layout _ k} . The layout distance may represent or may relate to a maximum available distance between respective vertices of the seed rectangle and a boundary of the substrate.

In some exemplary embodiments, as part of the layout distance calculation at block 304, when the corresponding diagonal is taken

From the origin O _k While extending, calculating and identifying the origin O _k And the corresponding intersection point T between the substrate boundaries _k As shown, for example, in fig. 9. The intersection point T may be found using a number of conventional approaches _k . When the cross point T is found _k Then, the following relationship is satisfied:

wherein

To be from the origin O _k To the point of intersection T _k The vector of (2). In other words, vector

Having a vector with diagonal

In the same direction.

At four vertices P of the first ring ₁₁ 、P ₁₂ 、P ₁₃ And P ₁₄ And cross point T ₁ 、T ₂ 、T ₃ And T ₄ Thereafter, the vertex-layout-distance V can be calculated by the following formula _{Layout _ k} ：

Subtracted term

Ensuring the last vertex P of the Nth ring _Nk Away from the intersection point T _k . In other words, only from P _1k V of onset _{Layout _ k} Long linear part for use at P _1k And T _k With (N-1) vertices being allocated between.

At the identified intersection point T _k Thereafter, each vertex of the loop antenna may be determined. One of the initial conditions is that the loop number of the loop antenna is N, and four vertices P of the first loop are determined in step 330 ₁₁ 、P ₁₂ 、P ₁₃ And P ₁₄ Four vertices of each of the second, third, …, and nth rings are recursively determined. Specifically, at block 305, for respective diagonals, respective distances between pairs of neighboring planar antenna vertices to be located along the respective diagonals are determined based at least in part on the layout distances calculated at block 304. For example, the respective distances between pairs of vertices of adjacent planar antennas to be positioned along respective diagonals may be determined so as to fit a predetermined number of loops N of the antenna while maximizing the utility of the available linear distance from the vertices of the seed rectangle to the boundary of the substrate. In this way, the available area of the substrate can be effectively utilized. In addition, in some exemplary aspects, an outermost planar antenna vertex of the planar antenna vertices of the respective planar antennas is spaced from the substrate boundary by no more than a predetermined threshold to efficiently utilize the available substrate area.

In some examples, the respective distances are determined at block 305 based at least in part on: a predetermined number of loops N of the planar antenna, a predetermined minimum spacing between adjacent vertices, a predetermined minimum spacing between adjacent traces, and/or any combination of one or more of these or other factors. Specifically, in one example, the vertices are divided into four groups, where each group forms a rectangular shape and the vertices in the same group are described as corresponding vertices. For example, the first group includes P ₁₁ 、P ₂₁ A _N1 The second group includes P ₁₂ 、P ₂₂ A _N2 The third group includes P ₁₃ 、P ₂₃ A _N3 And the fourth group includes P ₁₄ 、P ₂₄ A _N4 . Thus, P _3k And P _Nk In the same k-th group and is a corresponding vertex, and P ₃₃ And P ₄₂ Not in the same group and cannot be the corresponding vertex. For each group, P _jk And P _(j+1)k Is set to be greater than P _(j-1)k And P _jk Wherein j is 2 to N-1 and k is 1 to 4. In other words, the distance between two adjacent corresponding vertices increases towards the boundary of the substrate. In other words, in one example, as shown in fig. 10, the distance between the pair of adjacent antenna vertices becomes gradually larger in a direction from the innermost vertex to the outermost vertex. The distance gradually increasing in the direction from the corresponding vertex of the seed rectangle to the boundary may be implemented by various methods, such as an arithmetic series, a geometric series, an exponential series, or the like.

For example, a series of arithmetic differences may be used to assign the remaining vertices in each group. Let d _jk Is P in the k group _jk And P _(j+1)k And expressed in a recursive form as:

d _jk slope (1) _k ×(j-1)+d _1k (17)

And

d _1k ＝VVM (18)

wherein

Represents the vertex P _jk And P _(j+1)k The slope k is a constant of the kth group, which is two distances d _jk And d _(j+1)k And j is 1 to (N-2). Thus, each vertex in the kth group is positioned at the junction T _k And P _1k On the linear part of (A) and P _Nk And P _1k Is less than or equal to the vertex-layout-distance V _{Layout _ k} . In order to make the other forbidden region T _k And P _Nk Handwriting between twoHalf of the line center-to-center minimum spacing (TCCM), the following equation may be satisfied:

or

When for constant slope _k When equation (20) is solved, the following equation is obtained:

when equation (20) is combined with equations (16) and (17), the following equations are obtained:

in this way, two adjacent corresponding vertices P _jk And P _(j+1)k The distance between increases as j increases. This progression pattern between corresponding vertices is more clearly shown in fig. 10 in the first and fourth groups than in the second and third groups.

At block 306, the planar antenna vertices are positioned along respective diagonals based on respective distances between pairs of adjacent planar antenna vertices determined at block 305.

At block 307, the diagonal is indexed by i _{Diagonal line} Compared to the number of diagonals (i.e., four) of the seed rectangle to determine whether the procedures of block 305 and block 306 are to be repeated for additional diagonals of the respective antenna. If i is determined at block 307 _{Diagonal line} Less than the number of diagonals, then at block 308, i _{Diagonal line} One is incremented to correspond to the next diagonal of the four diagonals of the seed rectangle (e.g., the second diagonal). The procedure of

blocks

305 and 306 is then repeated for this next diagonal in the manner described above.

On the other hand, if i is determined at block 307 _{Diagonal line} Equal to the number of diagonals, indicating that the procedures of

blocks

305 and 306 have been performed for each of the four diagonals of the seed rectangle, then at block 309, a minimum vertex-to-vertex distance (VVM) is calculated to ensure that the minimum distance between two adjacent corresponding linear sections is greater than TCCM when the vertices are connected by linear sections or line segments, where the phrase "two adjacent corresponding linear sections" is used to refer to linear sections that are located in different rings but closer to each other than any other linear section. This is done by: defining diagonal vectors

Setting temporary vertex P' ₂₁ And P' ₂₂ Measuring connected temporary vertex P' ₂₁ And P' ₂₂ Linear part and connection P of ₁₁ And P ₁₂ And adjusting the value of VVM until the minimum distance is greater than TCCM. Details of this step are described further below.

Diagonal line vector is defined as follows

Wherein k is 1 to 4. When these diagonal vectors are

When placed at the origin (0, 0), they form a cross, indicating that they form four 90 degree angles, as shown in the middle of fig. 7.

Will temporarily distance D _p2 To is that ₅ Initialized to the value of TCCM. Vector quantity

And

defined by the following equation:

and

temporary vertex P' ₂₂ Defined in vector form as follows:

where the symbol "·" is the dot product between two vectors. Briefly, temporary vertex P' ₂₂ Diagonal line towards the outside of the ith seed rectangle

Is far away from P ₁₂ To achieve

Next, the VVM is temporarily initialized by the following equation:

temporary vertex P' ₂₁ Defined in vector form as follows:

and P' ₂₂ Again, temporary vertex P' ₂₁ In the direction of the ith seedDiagonal of outer part of sub-rectangle

Is far away from P ₁₁ To achieve

As shown in FIG. 8, compute connected temporary vertex P' ₂₁ And P' ₂₂ Linear part of and P ₁₁ And P ₁₂ The distance between the linear portions in between. Due to connection of temporary vertex P' ₂₁ And P' ₂₂ Linear part of and P ₁₁ And P ₁₂ The linear portions therebetween may not be parallel, with a plurality of distances between the two linear portions. At block 309, a determination is made whether a minimum distance D of the plurality of distances between the two linear portions is less than or equal to TCCM. If it is determined at block 309 that the minimum distance D of the plurality of distances is less than or equal to TCCM, then at block 311 the temporary distance D is _{p2 to 5} A predetermined amount is added and the above procedure of blocks 302 to 309 is repeated, including by using equations (9) - (13), until the minimum distance D is greater than TCCM. The final result of VVM is set to the value of the vertex-to-vertex minimum.

If, on the other hand, it is determined at block 309 that the minimum distance D of the plurality of distances is greater than TCCM, a planar antenna layout is generated at block 312 by interconnecting planar antenna vertices via respective straight portions to form a plurality of loops (e.g., N loops) sequentially through each of a plurality of diagonals of the respective planar antenna. In the case where the seed shape is a seed rectangle, each of the loops includes a plurality of straight portions and a plurality of planar antenna vertices, i.e., four straight portions and four planar antenna vertices. For example, the first loop of each loop antenna (such as the loop antenna shown in fig. 11) includes four vertices (i.e., P) ₁₁ 、P ₁₂ 、P ₁₃ And P ₁₄ ) And four linear sections (i.e., connected at P) ₁₁ And P ₁₂ L between ₁₁ Connection P ₁₂ And P ₁₃ L of ₁₂ Connection P ₁₃ And P ₁₄ L of ₁₃ And connection P ₁₄ And P ₂₁ L of ₁₄ ) (ii) a … (N-1) th ring includes four vertices (i.e., P) _(N-1)1 、P _(N-1)2 、P _(N-1)3 And P _(N-1)4 ) And four linear sections (i.e., connected at P) _(N-1)1 And P _(N-1)2 L between _(N-1)1 Connection P _(N-1)2 And P _(N-1)3 L of _(N-1)2 Connection P _(N-1)3 And P _(N-1)4 L of _(N-1)3 And connection P _(N-1)4 And P _N1 L of _(N-1)4 ) (not labeled in FIG. 11 for clarity); and the nth ring includes four vertices (i.e., P) _N1 、P _N2 、P _N3 And P _N4 ) And three linear sections (i.e. connections P) _N1 And P _N2 L of _N1 Connection P _N2 And P _N3 L of _N2 And connection P _N3 And P _N4 L of _N3 ). Fig. 11 shows a design of a loop antenna comprising a plurality of loops, the loop antenna designed according to the procedure 300.

At block 313, a plurality of additional straight portions are routed from at least two of the planar antenna vertices (specifically, from two terminal antenna vertices positioned at both ends, respectively, of the linear planar antenna layout) to one or more connector locations of a coordinate system of the reference substrate. A number of further straight sections are added to the planar antenna layout. In embodiments where the procedure 300 is employed to design an antenna assembly that includes multiple planar antennas to be disposed on respective layers of a multilayer substrate, the planar antenna layouts may be routed to a single connector location, or individually to separate connector locations corresponding to each antenna, or any combination of connectors.

At block 314, the antenna index i _{Antenna with a shield} And the number of antennas M of the antenna assembly to determine whether the procedure of blocks 302-313 will be repeated for additional antennas of the antenna assembly. If i is determined at block 314 _{Antenna with a shield} Less than the number of antennas M, then at block 315, i _{Antenna with a shield} Incremented by one to correspond to the next antenna (e.g., the second antenna) of the M antennas of the antenna assembly. The procedure of blocks 302 through 313 is then repeated for this next antenna in the manner described above. FIG. 12 showsThe design of six loop antennas, which may be designed according to the protocol 300.

If, on the other hand, i is determined at block 314 _{Antenna with a shield} Equal to the number of antennas M, indicating that the procedures of blocks 302 through 313 have been performed for each of the M antennas of the antenna assembly, and then, at block 316, which may be optional in some embodiments, exporting data corresponding to the generated planar antenna layout to a circuit board routing tool, a circuit board manufacturing tool, and/or an electromagnetic simulation tool.

In one example, by exporting data corresponding to the generated planar antenna layout to an electromagnetic simulation tool at block 316, one or more electromagnetic fields that may be generated by antennas of the antenna assembly may be simulated based on the exported data and based on a superposition of the plurality of electromagnetic field components from each of the plurality of straight portions of the planar antenna layout, respectively. For example, each ring based on the seed shape may be represented by a determined mathematical formula, such as a cartesian equation or a parametric equation, such that the strength of the EM field generated by each ring may be calculated by the pisa-sa-la law at any point in space based on the mathematical formula. In other words, due to the geometry and other aspects of the antenna assembly (such as using straight portions as interconnections in the antennas of the antenna assembly), the need to generate and employ detailed electromagnetic field maps may be avoided by instead enabling the electromagnetic field maps to be calculated theoretically based on the characteristics of the antenna assembly. The calculated electromagnetic field may then be mapped either alone or in combination with a more readily generated low density electromagnetic field mapping derived from the measurements. In other words, an antenna assembly designed according to the protocol 300 may be used as a basis for EMN to generate accurate high-density theoretical electromagnetic field maps without having to use expensive measurement equipment and without having to perform time-consuming and labor-intensive measurements.

As will be apparent from the description herein, an antenna assembly may be effectively designed in a repeatable manner based on a number of design parameters and/or constraints (such as seed shape, number of loops, TCCM, etc.) in accordance with the procedure 300. Each of the antennas of the designed antenna assembly may be printed, deposited, or fabricated on a respective substrate layer and may be used as the EM field generator 145 of the EMN system 100 of fig. 1. In addition, since the loop antenna is constructed using straight portions, the electromagnetic field generated by each linear portion can be theoretically accurately calculated using the pisa-sara law at any point in the EM volume.

Fig. 13 shows a diagram of a loop antenna layout designed by the method 300 of fig. 3. After all vertices are connected, additional layouts may be automatically generated based on appropriate design rules related to trace length and routing directionality. These rules may be specific to the PCB software program or design requirements. In one aspect, the antenna design created by the method 300 may be converted to a 2-dimensional DXF (drawing interchange format) CAD file, which is then imported into the Altium PCB layout software. The PCB layout software is not limited to the Altium PCB layout software but may be any software that one of ordinary skill in the art should readily understand and use.

Based on design rules or design requirements of the software, vertices P ₁₁ And P _N4 Are electrically coupled to a connector 1301, respectively, which includes at least two

conductors

1301a, 1301b of the loop antenna and completes the complete blueprint of the loop antenna.

After the design of the antenna assembly is completed, the antenna is fabricated by depositing a conductive material (e.g., silver or copper) on the substrate based on the antenna assembly design, as shown in fig. 13. The antenna printed on the substrate includes structural and/or geometric relationships between the loops, which relationships are described in detail below.

In an exemplary aspect, the vertices of the loop antenna may be divided into four groups. The first set of vertices includes P ₁₁ 、P ₂₁ … and P _N1 The second group of vertices includes P ₁₂ 、P ₂₂ … and P _N2 The third group of vertices includes P ₁₃ 、P ₂₃ … and P _N3 And the fourth set of vertices comprises P ₁₄ 、P ₂₄ … and P _N4 . Because of V _{Layout _ k} Different for each group, so one group of vertices may be more densely distributed than the other groups of vertices. As shown in FIG. 13, the vertices in the fourth group are more loosely distributed than the vertices in the other groups, and the vertices in the second or third group are more loosely distributed than the vertices in the first and fourth groupsThe vertices in (a) are more densely distributed.

In another aspect, two corresponding linear portions (e.g., L) _jk And L _(j+1)k ) The shortest distance between increases as j increases. In other words, the distance between two adjacent corresponding linear portions increases in a direction from the innermost linear portion to the corresponding outermost linear portion. Based on this structural and/or geometric relationship between the loop and the vertex, the loop antenna may cover as much of the substrate as possible while maintaining such a relationship.

In one embodiment, after connecting the vertex with the linear portion, another security measure may be employed to confirm that all requirements are met in the antenna design. For example, the shortest distance between two adjacent corresponding linear portions may be calculated again. In the case where there are any two adjacent corresponding linear portions, the shortest distance between the two is not greater than TCCM, the procedure 300 may be repeated for different vertex-to-vertex minimum distances VVM.

In one aspect, the design rule 300 may achieve maintaining substantially the same inductance for each loop antenna, as the inductance is defined based at least in part on the antenna geometry. The resistance of the loop antenna may vary with the copper thickness on each layer. Thus to ensure that the antenna assembly maintains the desired copper thickness, two additional layers are added (one on top and the other on the bottom). With these additional layers, the electroplating process of the vias should not add copper to the antenna layers on the inner layers. Thus, the copper thickness may depend only on the initial core material used and the selected copper weight. In another aspect, the PCB design may include more than one via per current carrying path to minimize series resistance and increase the robustness of each current path. By having more vias, the resistance can be predicted and automatically calculated with high accuracy based on the antenna geometry and controlled copper thickness.

Turning now to FIG. 14, there is illustrated a block diagram of a computing device 1400 that may function as the EMN system 100, the control workstation 102, the tracking device 160, and/or a computer executing the procedure 300 of FIG. 3. Computing device 1400 may include one or more of each of the following components: memory 1402, processor 1404, display 1406, network interface controller 1408, input device 1410, and/or output module 1412.

Memory 1402 includes any non-transitory computer-readable storage medium executable by processor 1404 for storing data and/or software that controls the operation of computing device 1400. In one embodiment, memory 1402 may include one or more solid state storage devices, such as flash memory chips. Alternatively, or in addition to one or more solid-state storage devices, the memory 1402 may include one or more mass storage devices connected to the processor 1404 through a mass storage controller (not shown in fig. 14) and a communication bus (not shown in fig. 14). Although the description of computer-readable media contained herein refers to solid-state memory, it should be appreciated by those skilled in the art that computer-readable storage media can be any available media that can be accessed by the processor 1404. That is, examples of computer readable storage media include non-transitory, volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. For example, the computer-readable storage medium may include: RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory technology, CD-ROM, DVD, blu-ray, or other optical storage, magnetic tape, magnetic stripe, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computing device 1400.

Memory 1402 can store applications 1416 and/or data 1414. When executed by the processor 1404, the application 1416 can cause the display 1406 to present a user interface 1418 on the display 1406.

The processor 1404 may be a general purpose processor, a special purpose Graphics Processing Unit (GPU) configured to perform certain graphics processing tasks while freeing up the general purpose processor to perform other tasks, a programmable logic device such as a Field Programmable Gate Array (FPGA), or a Complex Programmable Logic Device (CPLD), and/or any number or combination of such processors or devices configured to work independently or in concert.

The display 1406 may be touch-sensitive and/or voice-activated, enabling the display 1406 to function as both an input and an output device. Alternatively, a keyboard (not shown), mouse (not shown), or other data input device may be employed.

Network interface 1408 may be configured to connect to a network, such as a Local Area Network (LAN), a Wide Area Network (WAN), a wireless mobile network, a bluetooth network, and/or the internet, including wired and/or wireless networks. For example, the computing device 1400 may receive design requirements and predetermined variables and execute the procedure 300 of fig. 3 to design an antenna assembly. The computing device 1400 may receive updates to its software (e.g., applications 1416) via the network interface controller 1408. The computing device 1400 may also display a notification on the display 1406 that a software update is available.

In another aspect, the computing device 1400 may receive Computed Tomography (CT) image data of a patient from a server (e.g., a hospital server, an internet server, or other similar server) for use during surgical planning. Patient CT image data may also be provided to the computing device 1400 via removable memory (not shown in fig. 14).

Input device 1410 may be any device through which a user can interact with computing device 1400, such as a mouse, keyboard, foot pedal, touch screen, and/or voice interface.

The output module 1412 may include any connection port or bus, such as a parallel port, a serial port, a Universal Serial Bus (USB), or any other similar connection port known to those skilled in the art.

The application programs 1416 can be one or more software programs that are stored in the memory 1402 and executed by the processor 1404 of the computing device 1400. During the design phase of the loop antennas, one or more software programs in application 1416 may be loaded from memory 1402 and executed by processor 1404 to automatically design the loop antennas, taking into account certain parameters and/or constraints, such as seed shape information, number of loops in each loop antenna, and so forth. In some embodiments, during the planning phase, one or more of the applications 1416 guide the physician through a series of steps to identify targets, set target sizes, set treatment zone sizes, and/or determine an entry route for the targets for later use during a navigation or procedure phase. In some other embodiments, one or more software programs in the application programs 1416 are loaded on a computing device in an operating room or other facility where a surgical procedure is performed and used as a plan or map to guide a clinician in performing the surgical procedure, but without any feedback from the medical device used in the procedure to indicate the position of the medical device relative to the plan.

The application programs 1416 may be installed directly on the computing device 1400 or may be installed on another computer, such as a central server, and opened on the computing device 1400 via the network interface 1408. The application programs 1416 may natively run on the computing device 1400 as Web-based applications or in any other format known to those skilled in the art. In some embodiments, the application 1416 will be a single software program having all of the features and functions described in this disclosure. In other embodiments, the application 1416 may be two or more different software programs that provide various portions of these features and functions. For example, the application programs 1416 may include one software program for automatically designing a loop antenna, another software program for converting the design into a CAD file, and a third program for a PCB layout software program. In such cases, various software programs forming part of the application 1416 may be enabled to communicate with each other and/or import and export various data, including settings and parameters related to the design of the loop antenna. For example, a design for a loop antenna generated by one software program may be stored and exported for use by a second software program for conversion into a CAD file, and the converted file may also be stored and exported for use by a PCB layout software program for completing a blueprint for the loop antenna.

The application 1416 may be in communication with a user interface 1418 that generates a user interface for presenting visual interactive features to a user, such as on the display 1406 and for receiving input, such as via a user input device. For example, the user interface 1418 may generate a Graphical User Interface (GUI) and output the GUI to the display 1406 for viewing by a user.

In the case where computing device 1400 is usable as EMN system 100, control workstation 102 or tracking device 160, computing device 1400 may be linked to monitoring device 130, thus enabling computing device 1400 to control output on monitoring device 130 along with output on display 1406. The computing device 1400 may control the monitoring device 130 to display output that is the same as or similar to the output displayed on the display 1406. For example, the output on the display 1406 may be mirrored on the monitoring device 130. Alternatively, computing device 1400 may control monitoring device 130 to display output that is different from the output displayed on display 1406. For example, the monitoring device 130 may be controlled to display guidance images and information during a surgical procedure, while the display 1406 is controlled to display other outputs, such as configuration or status information of an electrosurgical generator (not shown in fig. 1).

The application programs 1416 may include one software program for use during a planning phase and a second software program for use during a navigation or procedure phase. In such cases, various software programs forming part of the application 1416 may be enabled to communicate with each other and/or import and export various settings and parameters related to navigation and therapy and/or the patient to share information. For example, a treatment plan generated by one software program during the planning phase and any of its component parts may be stored and exported for use by a second software program during the procedure phase.

Although various embodiments have been described in detail with reference to the accompanying drawings for purposes of illustration and description, it is to be understood that the methods and apparatus of the invention are not to be considered limiting. It will be apparent to those of ordinary skill in the art that various modifications can be made to the foregoing embodiments without departing from the scope of the present disclosure.

Claims

1. An antenna assembly for radiating at least one electromagnetic field for electromagnetic navigation, the antenna assembly comprising:

a substrate; and

a planar antenna comprising traces deposited on the substrate and arranged in a plurality of loops,

wherein respective distances between adjacent rings of the plurality of rings increase in a direction from an innermost ring of the plurality of rings to an outermost ring of the plurality of rings,

wherein the planar antenna is generated based on a seed rectangle, an

Wherein each loop of the planar antenna generated based on the seed rectangle can be represented by a determined mathematical formula to enable the electromagnetic field mapping to be calculated based on the characteristics of the antenna assembly.

2. The antenna assembly of claim 1, wherein each of the plurality of loops comprises a plurality of straight portions and a plurality of vertices.

3. The antenna assembly of claim 2, wherein each of the plurality of loops comprises four straight portions and four vertices.

4. The antenna assembly as defined in claim 3, wherein each of the plurality of vertices is disposed along one of four diagonals that bisect four respective vertices of a seed rectangle corresponding to the planar antenna.

5. The antenna assembly of claim 1, further comprising:

a connector having at least two terminals,

wherein the trace has two ends coupled to the two terminals, respectively.

6. The antenna assembly of claim 1, further comprising:

a plurality of planar antennas are arranged on the base,

wherein each of the plurality of planar antennas comprises a respective trace deposited on the substrate and arranged in a respective plurality of loops, an

Wherein, for each of the plurality of planar antennas, a respective distance between adjacent ones of the respective plurality of loops increases in a direction from an innermost one of the respective plurality of loops to an outermost one of the respective plurality of loops of the respective planar antenna.

7. The antenna assembly as recited in claim 6 wherein the substrate comprises a plurality of layers and the planar antenna, and each of the plurality of planar antennas is deposited on a respective layer of the plurality of layers.

8. The antenna assembly of claim 6, wherein the planar antenna and each of the plurality of planar antennas each comprise the same number of loops.

9. The antenna assembly of claim 6, wherein each of the loops of each of the plurality of planar antennas comprises a plurality of straight portions and a plurality of vertices.

10. The antenna assembly as recited in claim 6 wherein the planar antenna and the plurality of planar antennas each have a plurality of centroids relative to a plane of the substrate, the centroids being disposed in respective positions that are different from each other.

11. An electromagnetic navigation system, comprising:

an antenna assembly configured to radiate an electromagnetic field, the antenna assembly comprising:

a substrate, and

wherein respective distances between adjacent rings of the plurality of rings increase in a direction from an innermost ring of the plurality of rings to an outermost ring of the plurality of rings;

wherein the planar antenna is generated based on the seed rectangle; and

wherein each loop of the planar antenna generated based on the seed rectangle can be represented by a determined mathematical formula to enable an electromagnetic field mapping to be calculated based on characteristics of the antenna assembly;

a conduit;

an electromagnetic sensor fixed to the catheter and configured to receive a signal based on the radiated electromagnetic field;

a processor; and

a memory comprising instructions that, when executed by the processor, cause the processor to calculate at least one of a position or an orientation of the electromagnetic sensor based on the received signals.

12. The electromagnetic navigation system of claim 11, wherein each of the plurality of loops comprises a plurality of straight portions and a plurality of vertices.

13. The electromagnetic navigation system of claim 12, wherein each of the plurality of loops includes four straight portions and four vertices.

14. The electromagnetic navigation system of claim 13, wherein each of the plurality of vertices is disposed along one of four diagonals that bisect four respective vertices of a seed rectangle corresponding to the planar antenna.

15. The electromagnetic navigation system of claim 11, wherein the antenna assembly further comprises:

a connector having at least two terminals,

wherein the trace has two ends coupled to the two terminals, respectively.

16. The electromagnetic navigation system of claim 11, wherein the antenna assembly further comprises:

a plurality of planar antennas are arranged on the base,

17. The electromagnetic navigation system of claim 16, wherein the substrate includes a plurality of layers and the planar antenna, and each of the plurality of planar antennas is deposited on a respective layer of the plurality of layers.

18. The electromagnetic navigation system of claim 16, wherein the planar antenna and each of the plurality of planar antennas each comprise the same number of loops.

19. The electromagnetic navigation system of claim 16, wherein each of the loops of each of the plurality of planar antennas includes a plurality of straight portions and a plurality of vertices.

20. The electromagnetic navigation system of claim 16, wherein the planar antenna and the plurality of planar antennas each have a plurality of centroids relative to a plane of the substrate, the centroids disposed in respective positions that are different from one another.