Kathrein USA Inc v. Fractus SA

1. Case Identification

• Case #: IPR2019-00951
• Patent #: 7,932,870
• Filed: April 9, 2019
• Petitioner(s): Kathrein USA, Inc., T-Mobile US, Inc.
• Patent Owner(s): Fractus, S.A.
• Challenged Claims: 1, 4, 5, 7, and 9

2. Patent Overview

• Title: Interlaced Multiband Antenna Arrays
• Brief Description: The ’870 patent discloses an interlaced multiband antenna array for wireless communications. The technology is described as a conceptual juxtaposition of multiple mono-band antenna arrays, where a single multiband antenna element is used at positions where elements from the different mono-band arrays would coincide.

3. Grounds for Unpatentability

Ground 1: Claims 1, 4, 5, 7, and 9 are obvious over Raguenet in view of Shapiro.

• Prior Art Relied Upon: Raguenet (Patent 5,434,580) and Shapiro (Patent 5,043,738).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Raguenet disclosed the core structure of the claimed invention: an interlaced multiband antenna array using "composite" elements, which could be a "two-resonator patch." Raguenet’s arrays showed both interlaced arrangements of mono-band and multiband elements as well as arrays composed entirely of multiband elements. However, Raguenet did not explicitly describe the radio-electric behavior (i.e., similar radiation and impedance patterns) of its composite elements. Petitioner contended that Shapiro remedied this by disclosing a well-known type of "two-resonator patch"—a multiband, stacked-patch element with electromagnetically coupled portions—that was explicitly designed to have the similar radiation and impedance characteristics required by the claims. The combination of Raguenet's array architecture with Shapiro's specific, well-characterized multiband element rendered the claims obvious.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine the teachings because stacked patch elements, like those in Shapiro, were common, simple, and inexpensive implementations of the "two-resonator patch" element generically disclosed in Raguenet. A POSITA seeking to build a functional version of Raguenet's array would have been motivated to use a known, high-performance multiband element like Shapiro's to achieve predictable results in a multiband application.
  • Expectation of Success: A POSITA would have a high expectation of success, as substituting one known type of antenna element (Shapiro's stacked patch) for another (Raguenet's generic two-resonator patch) in a known array configuration was a simple design choice. Shapiro taught how to design its elements to operate at desired cellular frequencies, ensuring they would be functional in Raguenet's array.

Ground 2: Claims 1, 4, 5, 7, and 9 are obvious over Derneryd.

• Prior Art Relied Upon: Derneryd (International Publication No. WO 98/37592).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Derneryd, standing alone, disclosed all limitations of the challenged claims. Derneryd taught a base station antenna array operating simultaneously in two mobile communication frequency bands (e.g., 800-900 MHz and 1800-1900 MHz). This was achieved using a "single dual frequency patch antenna element"—a stacked-patch multiband element. Derneryd's figures depicted these dual-band elements arranged in an array where every position was occupied by a multiband element. Petitioner argued this satisfied the "juxtaposition" limitation, as the array resulted from conceptually overlaying a high-frequency array and a low-frequency array.
  • Motivation to Combine (N/A): As a single-reference ground, no motivation to combine was required. Petitioner argued that Derneryd’s disclosure of a functional base station antenna inherently implied that its multiband elements possessed similar radiation and impedance patterns across their operating bands, as this is a fundamental design criterion for such systems. Derneryd also disclosed operating on frequency combinations whose center frequencies were not integer dividers of one another, meeting another key limitation.

4. Key Claim Construction Positions

• "juxtaposition of a plurality of mono-band arrays": Petitioner argued this term described a conceptual framework for determining the final positions of antenna elements, not a physical manufacturing process or a requirement that the final product contain any mono-band elements. Based on this interpretation, an array comprised entirely of identical multiband elements (as shown in Raguenet and Derneryd) satisfied the limitation because its element locations correspond to where elements of two or more conceptual mono-band arrays would coincide.
• "multiband antenna": Petitioner applied the definition from the ’870 patent's specification, construing the term to mean an antenna with electromagnetically coupled portions that interact to produce "substantially similar" radiation and impedance patterns across multiple working frequency bands. This construction was central to the argument that Shapiro's well-defined element supplied a property not explicitly detailed in Raguenet.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §314(a) based on the General Plastic factors would be inappropriate. The core arguments were that: (1) the ’870 patent had not been the subject of any prior or pending post-grant proceedings; (2) Petitioner Kathrein USA, Inc. was not a party to the parallel district court litigations, making it a first-time filer on the patent; and (3) the petition challenged claims that were not at issue in the district court litigation. These facts were presented to distinguish the case from those where follow-on petitions are a concern and to support the fundamental fairness of instituting review.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1, 4, 5, 7, and 9 of the ’870 patent as unpatentable under 35 U.S.C. §103.