DCT

3:25-cv-02680

Fractus SA v. ResMed Inc

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 3:25-cv-02680, S.D. Cal., 10/09/2025
  • Venue Allegations: Plaintiff alleges venue is proper because Defendants reside in the Southern District of California and maintain a regular and established place of business in San Diego.
  • Core Dispute: Plaintiff alleges that Defendant’s wirelessly connected medical devices, used for remote patient monitoring, infringe five patents related to multi-band and miniature antenna technologies.
  • Technical Context: The technology at issue involves internal antenna designs that enable wireless devices to operate on multiple frequency bands while maintaining a small form factor, a critical feature for modern connected electronics.
  • Key Procedural History: The complaint alleges that Plaintiff provided Defendant with notice of the patents-in-suit via a letter in June 2021. Subsequent communications are cited to support allegations of willful infringement.

Case Timeline

Date Event
2002-02-19 Priority Date for U.S. Patent No. 8,593,349
2004-01-28 Priority Date for U.S. Patent No. 8,456,365
2004-01-28 Priority Date for U.S. Patent No. 8,674,887
2005-07-25 Priority Date for U.S. Patent No. 8,362,960
2006-07-18 Priority Date for U.S. Patent No. 11,031,677
2013-01-29 U.S. Patent No. 8,362,960 Issued
2013-06-04 U.S. Patent No. 8,456,365 Issued
2013-11-26 U.S. Patent No. 8,593,349 Issued
2014-03-18 U.S. Patent No. 8,674,887 Issued
2021-06-01 Plaintiff allegedly provides pre-suit notice to Defendant
2021-06-08 U.S. Patent No. 11,031,677 Issued
2022-11-01 Plaintiff allegedly provides notice of infringement by '960 and '677 patents
2025-10-09 Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,456,365 - "Multi-Band Monopole Antennas for Mobile Communications Devices"

The Invention Explained

  • Problem Addressed: The patent addresses the challenge of designing small, internal antennas for wireless devices that can operate efficiently across multiple frequency bands without performance being degraded by nearby electronic components (’365 Patent, col. 1:19-35).
  • The Patented Solution: The invention proposes a multi-band antenna structure comprising two radiating arms connected to a common conductor. A key aspect is that at least a portion of these arms are arranged on different planes, creating a three-dimensional structure. Furthermore, one of the radiating arms is shaped according to a "grid-dimension curve," a specific geometric construction intended to achieve miniaturization and multi-band performance (’365 Patent, col. 4:1-15; Abstract).
  • Technical Importance: This approach sought to provide a method for creating compact, internal antennas capable of supporting multiple cellular communication standards (e.g., GSM, UMTS) within a single small device, a key enabler for the development of modern smartphones and other connected devices (’365 Patent, col. 1:44-53).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶30).
  • Claim 1 of the '365 Patent includes these essential elements:
    • A mobile communication device comprising a housing, a printed circuit board (PCB) with a ground plane layer and feeding point, and communication circuitry.
    • A multi-band antenna including an antenna element that operates with the ground plane.
    • The antenna element comprises a common conductor, a first radiating arm, and a second radiating arm.
    • The common conductor includes a feeding port coupled to the PCB's feeding point.
    • At least a portion of the first and second radiating arms are arranged on different planes.
    • The first radiating arm is at least partially shaped according to a grid-dimension curve.
    • The PCB, circuitry, and antenna are all arranged inside the device housing.

U.S. Patent No. 8,674,887 - "Multi-Band Monopole Antenna for a Mobile Communications Device"

The Invention Explained

  • Problem Addressed: The patent identifies the need for miniature, high-efficiency internal antennas for mobile devices that must operate in multiple frequency bands, a task complicated by the limited available volume and proximity to other components (’887 Patent, col. 1:19-35).
  • The Patented Solution: The invention describes a multi-band antenna secured to a mounting structure and offset from the ground plane. The antenna features radiating arms, at least one of which is shaped as a "space-filling curve." This curve is specifically defined as having at least ten short segments connected at angles, with constraints on periodicity and segment length relative to the operating wavelength, to achieve a compact, multi-band design (’887 Patent, col. 2:56-67; Abstract).
  • Technical Importance: The use of precisely defined space-filling geometries provided a systematic way to design antennas that could fit into small devices while resonating at multiple, distinct frequency bands required by evolving cellular standards (’887 Patent, col. 1:36-44).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶41).
  • Claim 1 of the '887 Patent includes these essential elements:
    • A mobile communication device with communications circuitry and a circuit board (comprising a ground plane and feeding point).
    • A mounting structure positioned within the device.
    • A multi-band antenna secured to the mounting structure and laterally offset from an edge of the ground plane.
    • The antenna comprises a common conductor, first and second radiating arms, and a space-filling curve constituting at least part of the first radiating arm.
    • The space-filling curve is defined as comprising at least ten segments shorter than a tenth of the free-space operating wavelength, with each segment connected to its neighbor at an angle such that "no pair of adjacent segments defines a longer straight segment."

U.S. Patent No. 8,593,349 - "Miniature Antenna Having a Volumetric Structure"

  • Technology Synopsis: This patent describes a miniature antenna system with a non-planar, volumetric structure. The shape of the radiating arm is defined by a "grid dimension curve," which is a non-periodic curve with a specific mathematical property (grid dimension Dg > 1.3) designed to achieve miniaturization relative to the operating wavelength (’349 Patent, Abstract; Compl. ¶51).
  • Asserted Claims: At least independent claim 15 (Compl. ¶52).
  • Accused Features: The complaint alleges that the internal antenna in the Resmed AirCurve 10 products infringes the ’349 Patent (Compl. ¶53).

U.S. Patent No. 8,362,960 - "Handheld Device with Two Antennas, and Method of Enhancing the Isolation Between the Antennas"

  • Technology Synopsis: This patent relates to a handheld device with two separate antennas arranged on a "substantially rectangular ground plane." It claims a specific orthogonal arrangement where a first multi-band antenna is placed near a short side of the ground plane and extends parallel to a first side, while a second antenna extends parallel to a second, orthogonal side, a configuration intended to enhance electrical isolation between them (’960 Patent, Abstract; Compl. ¶62).
  • Asserted Claims: At least independent claim 1 (Compl. ¶63).
  • Accused Features: The complaint alleges that the dual-antenna configuration in the Resmed AirCurve 11 and AirSense 11 products infringes the ’960 Patent (Compl. ¶¶63-64).

U.S. Patent No. 11,031,677 - "Multiple-Body-Configuration Multimedia and Smartphone Multifunction Wireless Devices"

  • Technology Synopsis: This patent describes a wireless device with an antenna system having first and second antennas on a ground plane. The shape of the first antenna's perimeter, or "contour," is characterized by a "level of complexity" defined by specific mathematical "complexity factors" (F21 and F32) that fall within claimed numerical ranges, with at least one supported frequency band being a 4G standard (’677 Patent, Abstract; Compl. ¶73).
  • Asserted Claims: At least independent claim 1 (Compl. ¶74).
  • Accused Features: The antenna system in the Resmed AirCurve 11 and AirSense 11 products is alleged to infringe the ’677 Patent (Compl. ¶¶74-75).

III. The Accused Instrumentality

Product Identification

  • The accused products include the Resmed AirSense 10, AirCurve 10, AirSense 11, AirCurve 11, and Connectivity Module product lines (Compl. ¶16). These are medical devices used for treating sleep apnea.

Functionality and Market Context

  • The complaint focuses on the products' "built-in wireless connectivity, including for remote monitoring and management," which it describes as "central to the health benefits and commercial value of the Infringing Products" (Compl. ¶¶16, 19). Plaintiff cites Defendant’s advertising, which promotes features like "unprecedented access to therapy data and remote access to device settings" via "built-in cellular technology" (Compl. ¶32). The infringement allegations map the internal antenna components of these devices to the patent claims.

IV. Analysis of Infringement Allegations

U.S. Patent No. 8,456,365 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A mobile communication device, comprising: a device housing; a printed circuit board...comprising: a ground plane layer; a feeding point; a communication circuitry... The Resmed AirCurve 10 is a device with a housing containing a PCB with communication circuitry, a ground plane, and a feeding point. An annotated photograph identifies these components (Compl. p. 9). ¶31.a col. 4:1-15
a multi-band antenna capable of operating at multiple frequency bands...wherein the antenna element operates in cooperation with the ground plane layer The antenna allegedly operates in multiple cellular bands (GSM, WCDMA, LTE) in cooperation with the PCB's ground plane layer. A table of supported frequency bands is provided (Compl. p. 10). ¶31.b col. 4:26-30
the antenna element comprising: a common conductor; a first radiating arm...; a second radiating arm...wherein the common conductor includes a feeding port, the feeding port being coupled to the feeding point The accused antenna allegedly has a common conductor, a first radiating arm, and a second radiating arm, with the conductor's feeding port coupled to the PCB's feeding point. An annotated photograph identifies these structures (Compl. p. 11). ¶31.c col. 4:31-40
wherein at least a portion of the first radiating arm and at least a portion of the second radiating arm are arranged on different planes The accused antenna is allegedly a non-planar component folded into different planes. An annotated photograph with dashed lines illustrates where the antenna is allegedly folded (Compl. p. 11). ¶31.d col. 4:41-44
wherein the first radiating arm is at least partially shaped according to a grid-dimension curve The complaint alleges the shape of the first radiating arm satisfies the definition of a grid-dimension curve and provides a specific calculation (Dg = 1.37 > 1) based on an analysis of the component's geometry (Compl. p. 12). ¶31.e col. 4:45-48
wherein the printed circuit board, the communication circuitry, and the multi-band antenna are arranged inside the device housing The internal components, including the PCB, circuitry, and antenna, are located inside the device's plastic housing. A composite image shows the components both separately and assembled within the housing (Compl. p. 12). ¶31.f col. 4:52-55
  • Identified Points of Contention:
    • Scope Questions: A potential dispute may arise over whether the term "mobile communication device," which the patent specification primarily illustrates with handheld telephones (’365 Patent, col. 3:56-61), can be construed to cover a stationary CPAP machine that incorporates cellular connectivity.
    • Technical Questions: The central technical question will be whether the accused antenna's first radiating arm is, in fact, "shaped according to a grid-dimension curve" as required by the claim. This will likely involve competing expert analyses of the component's geometry and the proper application of the grid dimension formula presented by the plaintiff.

U.S. Patent No. 8,674,887 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A mobile communication device comprising: communications circuitry; a circuit board comprising a ground plane and a feeding point...; a mounting structure positioned within the...device, a section of the mounting structure extending over the circuit board The Resmed AirCurve 10 allegedly contains circuitry, a PCB with a ground plane, and a plastic mounting structure that extends over the PCB. An annotated photograph identifies these components (Compl. p. 16). ¶42.a col. 3:1-10
a multi-band antenna secured to the mounting structure and laterally offset from an edge of the ground plane An antenna is allegedly secured to the mounting structure and is positioned offset from the PCB's ground plane. The complaint provides a list of supported frequency bands (Compl. p. 16). ¶42.b col. 3:11-14
the multi-band antenna comprising: a common conductor coupled to the feeding point; first and second radiating arms coupled to and extending from the common conductor The accused antenna allegedly comprises a common conductor coupled to the feeding point, with first and second radiating arms extending from it. An annotated photograph identifies these components (Compl. p. 17). ¶42.c col. 3:15-18
a space-filling curve constituting at least a part of the first radiating arm, wherein the space-filling curve comprises at least ten segments that are shorter than a tenth of a free-space operating wavelength... The first radiating arm is alleged to be shaped as a space-filling curve with more than ten segments, each shorter than λ/10 for LTE 12. An annotated image highlights the segments and provides a calculation (Compl. p. 18). ¶42.d col. 3:19-27
...each of the segments being connected to its neighboring segments at an angle such that no pair of adjacent segments defines a longer straight segment... The complaint alleges the geometry of the radiating arm meets the specific angular and non-collinear requirements of the claimed space-filling curve, as shown in the annotated photograph (Compl. p. 18). ¶42.d col. 3:25-34
  • Identified Points of Contention:
    • Scope Questions: As with the ’365 patent, a question may be raised as to whether a stationary medical device constitutes a "mobile communication device" within the meaning of the claims.
    • Technical Questions: The infringement analysis will likely focus on the highly detailed, multi-part definition of "space-filling curve." The defendant may argue that the accused antenna's geometry does not meet one or more of the specific limitations, such as the minimum number of segments, the segment length relative to wavelength, or the prohibition on adjacent segments forming a longer straight line.

V. Key Claim Terms for Construction

"grid-dimension curve" (’365 Patent, Claim 1)

  • Context and Importance: This term is a central technical limitation defining the shape of a key component (the first radiating arm). The infringement allegation for the ’365 patent hinges on whether the accused antenna's shape meets this definition, for which the complaint provides a specific mathematical formula (Compl. p. 12).
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification states that the curve is based on "a grid of squares, rectangles, triangles, or any other suitable polygon," which may suggest the specific geometry is not limited to a single form (’365 Patent, col. 2:37-39). The patent also describes the curve as a way to "tune or partially tune the resonant frequency," suggesting a functional rather than purely structural definition (’365 Patent, col. 3:3-5).
    • Evidence for a Narrower Interpretation: The specification provides a specific formula for calculating the grid dimension, Dg = [log(N2) - log(N1)] / [log(L1/L2)], and states that for a grid-dimension curve, "the value of Dg is larger than 1" (’365 Patent, col. 2:48-55). A party could argue that any shape not satisfying this precise mathematical test falls outside the claim scope.

"space-filling curve" (’887 Patent, Claim 1)

  • Context and Importance: This term is not just recited but is defined within the body of claim 1 by a series of specific geometric constraints. Infringement depends entirely on whether the physical structure of the accused antenna satisfies every element of this detailed definition.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes space-filling curves as a means "to reduce the overall size of the antenna" and notes that the curve "is not limited to the particular geometry shown" in the figures, suggesting the focus is on the function of miniaturization rather than a single, rigid shape (’887 Patent, col. 2:63-65, col. 4:21-22).
    • Evidence for a Narrower Interpretation: Claim 1 itself provides a highly limiting definition, requiring "at least ten segments," each "shorter than a tenth of a free-space operating wavelength," and connected at an angle such that "no pair of adjacent segments defines a longer straight segment." A party would argue this language serves as its own lexicography, and any deviation from these explicit geometric rules, regardless of function, is non-infringing. The abstract also refers to the curve as having segments that are "spatially arranged," reinforcing the importance of the specific geometry (’887 Patent, Abstract).

VI. Other Allegations

Indirect Infringement

  • The complaint alleges induced infringement for all five patents. The basis for inducement is Defendant's advertising, marketing, and instructional materials that allegedly direct customers and end-users to use the accused products' built-in cellular connectivity for remote data access, thereby performing the infringing use (Compl. ¶¶32, 43, 54, 65, 76).

Willful Infringement

  • The complaint alleges willful infringement based on Defendant's alleged pre-suit actual knowledge of the patents-in-suit. This knowledge is alleged to have been established by a notice letter sent in June 2021, which was acknowledged by Defendant, and subsequent communications regarding additional patents and products (Compl. ¶¶18, 21, 34, 45, 56, 67, 78).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of claim construction and geometric analysis: can Plaintiff prove that the physical shapes of the accused antennas meet the precise, multi-part mathematical definitions of "grid-dimension curve" and "space-filling curve" as required by the asserted claims? The dispute will likely feature competing expert testimony on the measurement and interpretation of these complex geometries.
  • A second key question will be one of definitional scope: does the term "mobile communication device," which the patent specifications consistently exemplify with handheld phones, extend to cover stationary, mains-powered medical equipment that incorporates a cellular modem for remote data transmission?
  • A third central question will be one of evidence and proof: does the factual evidence, derived from teardowns and analysis of the accused ResMed products, support the specific numerical calculations and structural assertions made in the complaint's annotated photographs, or will discovery reveal a technical mismatch between the patent claims and the actual operation and construction of the accused antennas?