US 5693429

I'll search for authoritative information on this patent, including any CAFC/litigation activity.

Let me check specifically for litigation and CAFC docket activity.

US 5,693,429 — Verified Summary

Search scope performed: Google Patents full text, USPTO/patent-grant records (uspto.report), Federal Register grant/ licensing notice, Unified Patents, RPX/insight, and open-web searches for "5,693,429" / "5693429" paired with litigation, Federal Circuit, PTAB, and IPR terms.

Bibliographic data (from the authoritative full text and corroborating records)

Corroboration: the Army published this patent for licensing at 63 FR 9212 (Feb. 24, 1998), listing the identical title, inventor set, patent number and Dec. 2, 1997 issue date — see https://www.govinfo.gov/content/pkg/FR-1998-02-24/html/98-4672.htm.

Abstract (as printed)

"A laminated ceramic ferroelectric material has adjacent layers of Barium Strontium Titanate (BSTO)–oxide composite stacked in order of descending oxide content and sized in thickness to produce a generally equal capacitance across each layer, resulting in a material having a graded dielectric constant for use in phased array antenna, for example. The oxides are from the metallic oxide group consisting of alumina, zirconia and magnesia and the layers are produced by tape casting."

(Some third-party databases reproduce a typo, "Barium ontium Titanate," for "Barium Strontium Titanate." The patent itself also contains the typographical error "ferrolectric" in the claim text, which I preserve below.)

Plain-language overview of the independent claims

Claim 1 — the "graded dielectric constant" product claim.
A laminated (multi-layer, co-fired) ceramic ferroelectric body with a graded dielectric constant. Elements:

• a plurality of adjacent layers with no air gaps between discrete layers;
• each layer made of a composition of 0–100% Ba₁₋ₓSrₓTiO₃ where x > 0.0 but < 0.75, plus 100–0 wt% of at least one low-dielectric-constant / low-dielectric-loss oxide chosen from the closed group Al₂O₃, ZrO₂, MgO;
• the BSTO:oxide ratio differs in each layer; and
• the layers are stacked in order of decreasing dielectric constant and laminated together.

In plain terms: a stack of ceramic tapes whose compositions step from essentially pure BSTO (high ε′) down to essentially pure oxide (low ε′), bonded into a single dense body, so the stack acts as a built-in, compositionally graded impedance-matching transition from air (ε′≈1) into a high-ε′ ferroelectric phase-shifter material (ε′≈3300 for BSTO).

Claim 10 — the "selectively graded dielectric constant" product claim (broader genus).
Same "no air gap," multi-layer, decreasing-dielectric-constant-order, laminated structure, but each layer is composed from:

• Ba₁₋ₓSrₓTiO₃ (x > 0.00 and < 0.75),
• at least one low-dielectric-constant, low-dielectric-loss oxide, and
• a low-dielectric-constant, low-dielectric-loss "adjusting material";

the three constituents total 100 wt%, and each composition contains a different ratio of materials so layers have different dielectric constants.

The difference from claim 1: claim 10 expressly adds a third, independently selectable knob — the adjusting material (per dependent claim 11, a polymer or silica, with claim 16 capping it at 0–20 wt%). This is the claim the specification links to matching below ε′≈9 (pure alumina) via BSTO/polymer or BSTO/low-ε′ silica composites.

Key dependent limitations to note (they carry most of the technical specificity):

• Cl. 2: layer thickness varies inversely with BSTO content.
• Cl. 3: thicknesses chosen to give constant capacitance across every layer.
• Cl. 4: thickness computed from ε′ = Ct/Aε₀ (ε′ = layer dielectric constant, C = capacitance of BSTO, t = thickness, A = area).
• Cl. 5: ratios selected for a linear grading of dielectric constant.
• Cl. 6: ratios selected for a prescribed non-linear grading function.
• Cl. 7: oxide = alumina, zirconia, magnesia "and mixtures thereof."
• Cl. 8: lamination = heat 150–400 °C, uniaxial press 5,000–10,000 psi, then sinter.
• Cl. 9: lamination = warm isostatic press at ~70 °C, 5,000–10,000 psi, then sinter.
• Cl. 12: ratios chosen to follow a predetermined mathematical function; cl. 13: oxide from alumina/zirconia/magnesia; cl. 14–15: same lamination routes as cl. 8–9; cl. 16: adjusting material 0–20 wt%.

Notable observations / internal inconsistencies (flagged, not corrected)

1. Ordering terminology conflicts within the document. Claim 1 and claim 10 recite layers "arranged in order of decreasing dielectric constant," and the abstract says "descending oxide content." The detailed description, however, states the layers "are arranged in order of increasing dielectric constant" (and separately that aqueous tape circles "are stacked in order of descending oxide content"). Since a stack is physically the same object viewed from either end, this reads as an orientation/labeling inconsistency rather than a substantive one — but it is a real drafting discrepancy and a potential claim-construction issue.
2. Claim 1 literally covers a 100% oxide top layer ("100 to 0% by weight" of oxide) — i.e., a pure-alumina layer — and a 0%-oxide layer (pure BSTO). All 16 claims are product/by-structure claims; despite the specification repeatedly describing "a method for producing" the composites, no method claims issued.
3. Claim 3 says "constant capacitance" while the abstract and description say "generally equal"/"approximately equal" capacitance — a possible written-description/support tension worth noting.
4. The only prior-art reference cited on the face of the patent is US 5,312,790 (Sengupta et al.), "Ceramic Ferroelectric Material," issued 1994-05-17, same assignee (the Army).
5. The patent has an unusually large forward-citation footprint in the tunable-dielectric/Paratek–BlackBerry line (e.g., US 6,377,142 "Voltage tunable laminated dielectric materials for microwave applications"), and is cited in foreign prosecution (e.g., EP 2 492 256 A3 search report; DE 60112335 T2).

Litigation / CAFC 2026 docket check — no hits found

• Searches pairing "5693429" or "5,693,429" with litigation, lawsuit, infringement, Federal Circuit / CAFC / Court of Appeals, PTAB, IPR, and reexamination returned no docket entries, appeals, or PTAB proceedings involving this patent. A targeted search for a CAFC 2026 docket for this number returned zero results.
• Third-party aggregators (RPX/insight) show "0 Petitions" and no accused products for US 5,693,429.
• Practical note supporting the null result: the patent's anticipated expiration was 2015-01-20 and its status is "Expired – Fee Related." A patent that expired in 2015 cannot be asserted for post-expiration infringement, so a 2026 Federal Circuit appeal of a live infringement case on this patent is unlikely absent a much earlier-filed case still on appeal; I found no evidence of such a case.

Uncertainty statement: I could not access the USPTO PatentCenter/Patent Trial and Appeal Board APIs or a live CAFC docket system directly, and public web coverage of a 1997 Army-owned ceramic patent's litigation history is sparse. Accordingly, I can state with confidence that no litigation or CAFC 2026 activity for US 5,693,429 is reflected in the sources I could reach, but I cannot affirmatively rule out an obscure, unindexed older district-court or appeal proceeding. The bibliographic and claim content above is taken from the authoritative full patent text (https://patents.google.com/patent/US5693429/en) and the Federal Register licensing notice (https://www.govinfo.gov/content/pkg/FR-1998-02-24/html/98-4672.htm), with the "1995-01-19" priority date shown by one aggregator (Unified Patents) rejected in favor of the authoritative 1995-01-20 date.

I'll search litigation-focused sources for US 5,693,429 / 5693429 specifically.

Bottom line

No litigation is known involving US 5,693,429. Every targeted query I ran returned zero dockets, complaints, judgments, appeals, ITC investigations, or PTAB proceedings tied to this specific patent number. I am reporting this as a verified null result, with the evidence and the important exclusions below.

Searches run (all number-specific)

Result: no case found. There is therefore no plaintiff, defendant, jurisdiction, case number, filing date, or status to report.

What the number does appear in — and why it is not litigation

1. EP 2 492 256 A3 search report — US 5 693 429 A is cited as an "X" (category) document against claims 1–7, and the family table shows "NONE" for US 5,693,429 family members. This is prosecution citation, not litigation. https://patentimages.storage.googleapis.com/1e/d4/d0/7d8644ca15118d/EP2492256A3.pdf
2. EP 2 590 190 A2 specification — lists "No. 5,693,429" in a string of Sengupta BST patents incorporated by reference. Again, specification citation, not a case. http://patentimages.storage.googleapis.com/ac/60/51/acfac92b821f1a/EP2590190A2.pdf
3. uspto.report bibliographic page — confirms assignee (Secretary of the Army), inventors, and grant date; contains no litigation tab or case list. https://uspto.report/patent/grant/5,693,429

Near-miss identifiers I deliberately did not count (per the literal-ID rule)

These surfaced in searches and are different alphanumeric IDs that must not be conflated with US 5,693,429:

• JP 5693429 B2 — Japanese Patent No. 5693429, "モータ制御装置、モータ制御方法" (motor control device/method), applicant Mitsubishi Heavy Industries, registered 2015-02-13. This is a JPO patent, not the US patent, and is unrelated subject matter.
• **"the '429 patent" in Headwater Research LLC v. Samsung Electronics Co., Ltd., No. 2:24-cv-00228 (E.D. Tex.)** — the shorthand "'429" in that case refers to one of Headwater's wireless-device service-policy patents ("secure modem subsystem"; secure memory partitions), not US 5,693,429. That is an entirely different patent that happens to end in the same three digits.
• U.S. Pat. No. 5,191,573, 5,966,440, etc. in an unrelated reexamination litigation-search report — different numbers again.

Any of these would be a false positive if reported as "litigation involving 5,693,429."

Why the null result is structurally expected (not just an artifact of search)

This goes beyond the earlier expiration observation and gives an independent legal reason to expect no district-court litigation:

• The patent is Government-owned. Assignee is the United States of America as represented by the Secretary of the Army. Notably, the patent itself contains no § 1498(a) "manufactured for the Government" authorization-and-consent clause — the "GOVERNMENTAL INTEREST" paragraph is instead a license-back clause ("may be manufactured, used and licensed by or for the U.S. Government without payment to us of any royalty thereon"). That asymmetry matters: a patent whose specification lacks a § 1498(a) consent provision is not automatically deprived of remedies against Government contractors, but as a practical matter the Army's chosen commercial route for this family was licensing, not enforcement — it published the patent for licensing at 63 FR 9212 (Feb. 24, 1998) and the technology was commercialized through the Paratek Microwave / BlackBerry line of forward-citing patents (e.g., US 6,377,142), not through infringement suits.
• Statutory bar on the most natural defendant. Suits against the United States for Government use of an Army-owned patent lie exclusively in the Court of Federal Claims under 28 U.S.C. § 1498(a), not in district court. That class of case would not appear as a "patent infringement" docket entry in the databases queried, and I found no § 1498 action either.
• Expiration. Anticipated expiration 2015-01-20; status "Expired – Fee Related." No post-expiration damages are available for the claimed composition, so live 2026 exposure is essentially impossible.

Reconciling with the prior section: no contradiction. The previously generated summary also reported zero litigation/PTAB/CAFC hits; my independent number-specific searches reach the same conclusion and add the JP 5693429 and Headwater "'429" false-positive exclusions, which the earlier section did not identify.

Residual uncertainty — stated explicitly

I could not directly execute a live docket lookup. Specifically, I did not obtain a rendered answer from the Unified Patents litigation caselist (https://portal.unifiedpatents.com/litigation/caselist), the PACER Case Locator, the CourtListener/RECAP search API, a Docket Alarm patent page for 5,693,429, or a Lexis/Westlaw KeyCite litigation-history report. My final query against litigation/complaint language was cut off by a tool-step limit. Accordingly:

• I can state with high confidence that no litigation involving US 5,693,429 is reflected in any source I reached, and that the patent's ownership, licensing history, and 2015 expiration make a live or recent case very unlikely.
• I cannot rule out an obscure, unindexed, or very old proceeding (e.g., a pre-2015 district-court or § 1498 action that never generated public web coverage). If you need a belt-and-suspenders confirmation, the three definitive checks are: (1) Westlaw/Lexis KeyCite on the patent number, (2) PACER Case Locator restricted to nature-of-suit 830, and (3) Unified Patents and Docket Alarm patent-specific pages. I was unable to complete those direct lookups here.

PTAB / AIA Trial Analysis — US 5,693,429

Proceedings overview

Total AIA trial proceedings on US 5,693,429: zero. The USPTO Open Data Portal (ODP) structured proceedings list returns no IPR, PGR, or CBM filings against this patent, and independent web verification (Google Patents "Cited By"/family, PTAB E2E-style petition-document searches, and aggregator coverage) surfaces no petition, no institution decision, no Final Written Decision, and no appeal. The bottom-line defensive posture is unusual and, in this instance, favorable to an accused infringer by default: this is a 2015-expired, Army-owned, pre-AIA patent that was never once challenged at the Board — not because it was hardened by surviving IPRs, but because it was never commercially asserted (US5693429 — anticipatory expiration 2015-01-20; status "Expired – Fee Related"). There is no IPR estoppel to navigate, but there is also no invalidating FWD to lean on; any defense must be built from scratch in district court or by way of an ex parte reexam route.

Caveat on the "429" search noise. Virtually every web hit for a "429 patent" in the PTAB context concerns different patents — e.g., the KaiJet/Sanho port-extension patent US 10,572,429 (IPR affirmed at Sanho Corp. v. Kaijet Tech. Int'l, CAFC 2024) and the Mobotix video-surveillance '429 patent (IPR2013-00335). Those results are not this patent. Additionally, US 5,693,429 appears in numerous PTAB petition exhibits only as an IDS/citation-list entry (including inside unrelated petitions' prior-art bibliographies) — appearance in an exhibit is not a proceeding against it. Do not conflate these.

Proceedings (by most-impactful-first)

None to report.

No AIA trial proceeding has ever been instituted on, or even filed against, US 5,693,429. Accordingly, the per-proceeding template (petitioner, panel, grounds, institution, FWD, settlement, appeal) has no entries to populate.

Several legal-structural reasons explain the null result, and they matter to a defendant:

Verification trail (negative evidence).

• USPTO ODP structured proceedings list: no AIA trials for 5,693,429 (canonical source for this task).
• Google Patents family/legal-events for US5693429: no PTAB or IPR filings recorded; the only "family" entries are the parent/continuation pair (US 08/376,194 → US 08/647,260) — https://patents.google.com/patent/US5693429/en
• The patent's forward-citation "Cited By" list (137+ entries) is composed exclusively of patent documents and third-party applications, not PTAB decisions — nothing in the Board's IPR/reexam body of work cites this patent as an instituted target.
• The only Office-examination-adjacent references to US 5,693,429 found in the wild are as a cited prior-art document (e.g., a PCT/US2019 written opinion citing it merely as background) and in foreign search reports (EP 2 492 256 A3 lists US 5,693,429 A as an X-category reference against another party's claims 1–7 — i.e., the '429 is used to reject someone else, not to be challenged itself).

Strategic summary

Claim status: all 16 claims remain legally intact — but only because the patent is dead. No claim of US 5,693,429 has been canceled, narrowed, disclaimed, or held unpatentable in any PTAB proceeding, because no proceeding exists. Claims 1 and 10 (the two independents) and dependents 2–9 and 11–16 were issued 1997-12-02 and were never touched post-grant. This is a distinction that matters enormously: "all claims sustained" here does not mean "hardened"; it means "never stress-tested." Contrast that with a typical asserted patent, where survival means a Board panel and a Federal Circuit panel both upheld the claims. There is no FWD to cite, no cancellation to leverage, and no panel reasoning to quote.

Estoppel landscape: § 315(e)(2) estoppel is a non-issue. Because no IPR/PGR was ever filed, there is no petitioner, no real party in interest, and no privy laboring under § 315(e)(2)'s bars against raising grounds they "raised or reasonably could have raised." For a defendant asserted against today, the entire prior-art universe is available — § 102 and § 103 art in patents, printed publications, and system/sale/public-use art (which IPR could never have reached anyway). Nothing is foreclosed. That is the one genuine upside of the empty docket, but it is a thin one: the far more decisive fact is the expiration date, discussed next.

Pattern signals: none — the absence is itself the signal. This is not a case of a defensive aggregator (Unified Patents, RPX, or otherwise) systematically harvesting an asserted SEP-adjacent or troll-held patent. The '429 is U.S.-Government-owned (Secretary of the Army / Army Research Laboratory), was offered for non-exclusive, exclusive, or partially exclusive licensing under 37 CFR 404.6 (63 FR 9212, 1998-02-24), and carries a royalty-free Government-use license ("may be manufactured, used and licensed by or for the U.S. Government without payment to us of any royalty"). The combination — Government title, no commercial assertion campaign, an expiration date of 2015-01-20 — explains why no IPR was ever filed. Well-asserted patents attract IPRs; this patent was never asserted in a way that would create a petitioner with standing and incentive. The prior-art-heavy Paratek/BlackBerry forward-citation line (137+ citing documents, e.g., US 6,377,142 "Voltage tunable laminated dielectric materials for microwave applications") shows the technology was heavily built upon — but built upon as background art in new filings, never as an IPR target.

Recommended next steps

1. If you hold a demand letter asserting US 5,693,429, first confirm the date. The patent's anticipated expiration was 2015-01-20 and its status is "Expired – Fee Related." A patent that expired in early 2015 cannot support post-expiration infringement liability; damages (if any) would be confined to the pre-expiration window, and a § 286 six-year damages look-back bar forecloses recovery for conduct before ~2009 even in a hypothetical timely suit. Any 2026 assertion of this patent should be treated as presumptively non-viable on its face, independent of invalidity. Source: https://patents.google.com/patent/US5693429/en (legal-status block).

2. There is no FWD to link or quote. Because zero IPRs were filed, I cannot and do not point you to a Final Written Decision, an institution decision, or a CAFC disposition for this patent — none exists. Any summary asserting a "FWD for IPRxxxx-xxxxx on US 5,693,429" is fabricated or misattributed to a different '429.

3. If you nevertheless need to challenge the claims (e.g., to clear a portfolio or support a declaratory-judgment posture), the toolbox is fully open, not estoppel-limited:

   • Invalidity in litigation under § 102 (anticipation) and § 103 (obviousness), leveraging the same art the patent itself cites — note the only reference cited on the '429's face is US 5,312,790 (Sengupta et al., "Ceramic Ferroelectric Material," issued 1994-05-17, same Army assignee), which shares inventors and subject matter and is a natural obviousness starting point. Combine it with the Sengupta-family siblings (US 5,427,988 BSTO-MgO; US 5,486,491 BSTO-ZrO₂; US 5,635,433 BSTO-ZnO; US 5,635,434 BSTO-Magnesium-Based) — all pre-1995 filings in the same family and all highly relevant to a § 103 challenge.
   • § 112 written-description / enablement attacks, which the intrinsic record actually supports: the specification claims the "layers [are] arranged in order of increasing dielectric constant" while claims 1 and 10 recite "decreasing dielectric constant" (a real internal inconsistency), and claim 3's "constant capacitance" is described elsewhere as merely "generally equal"/"approximately equal" — a potential support gap. These are exactly the grounds an IPR petitioner could not have raised but a district-court defendant can.
   • Ex parte reexamination as a lower-cost PTAB-adjacent option — though note the expired-patent, no-amendment posture and the fact that this would be the first Office validity challenge in the patent's ~30-year history.

4. Active-proceeding milestones: none to track. No trial is pending, so there are no statutory § 316(a)(11) one-year FWD deadlines, no institution-decision dates, and no oral-hearing dates to monitor for this patent. Any calendaring entry purporting to reflect a live PTAB trial on US 5,693,429 is erroneous.

5. Bottom line for a defendant: the correct defensive characterization is not "the patent survived IPRs and is hardened" and not "claims 1–5 were canceled." It is: "No AIA trial was ever filed; no claim has ever been canceled; the patent expired 2015-01-20; and the entire § 102/§ 103/§ 112 prior-art field is unencumbered by estoppel." Lead with expiration; keep the invalidity case in reserve.

Uncertainty statement (required). I could not directly query PTAB E2E or the CAFC docket systems in this session; the negative result is sourced primarily from the authoritative structured USPTO ODP proceedings block, corroborated by web search (Google Patents family/legal-events, third-party petition exhibits, and foreign/domestic search reports that reference the '429 as prior art rather than as a challenged patent). I can state with high confidence that no AIA trial proceeding exists for US 5,693,429, and I note that the patent's 1995 priority, 2015 expiration, and non-financial subject matter structurally foreclose PGR and CBM and largely moot IPR. I cannot affirmatively rule out an unindexed, non-AIA Office proceeding (e.g., an ex parte reexam request) or an obscure pre-2012 district-court action, but I found no evidence of either, and I will not invent a proceeding number, panel, or disposition to fill the template.

I'll research the assignment record for US 5,693,429, starting with the USPTO Assignment Center and cross-referencing aggregators.

Let me try to access the Assignment Center records directly and check for any recorded conveyances.

Found a key lead — the Army's exclusive licensing to Paratek Microwave. Let me investigate that and whether '429 was included.

Ownership & Assignment Analysis — US 5,693,429

Access note / honesty statement up front: I was unable to pull the Assignment Center record page for 5693429 directly (the tool returned search-engine results rather than the Assignment Center's reel/frame table), and I hit my research step limit before I could brute-force the query. The findings below are assembled from Google Patents legal events, uspto.report, the Federal Register (which is where U.S. Government patent technology-transfer actions are published), and assigned-patent metadata. Where a reel/frame would normally go, I say so explicitly rather than inventing a number. Verify the null below at https://assignmentcenter.uspto.gov/ (search → Patent Number → 5693429).

Inventors

The application is a continuation of Ser. No. 08/376,194 (filed 1995-01-20, now abandoned); the inventive entity of 7 is consistent with a government-laboratory research group rather than a startup team.

Pattern note (flagged, not asserted as a finding): The one inventor I can corroborate — Louise Sengupta — is also a named inventor on the private Sengupta patent US 5,830,591 ("Multilayered ferroelectric composite waveguides," filed 1996-04-29, issued 1998-11-03, assignee: Sengupta) and on the Paratek-associated ferroelectric line. Separately, the U.S. Army published an intent to grant Paratek Microwave, Inc. (Columbia, MD) an exclusive 37 CFR 404 license to a sibling ARL Sengupta patent (US 5,427,988, "Ceramic Ferroelectric Composite Material—BSTO-MgO") — see the Federal Register notice at https://www.federalregister.gov/documents/full_text/xml/2001/05/17/01-12491.xml. That is consistent with the ARL ferroelectric team's work migrating into the private sector by license, not by assignment, with the lead inventor connected to the licensee. I did not find evidence that any inventor assigned the '429 away, so I will not frame this as a fire-sale or a departure-driven transfer. It is a licensing/tech-transfer pattern, not an ownership-transfer pattern.

Original assignee

The United States of America, as represented by the Secretary of the Army (work performed at the U.S. Army Research Laboratory, Adelphi, MD). Confirmed by the patent's own front page and by uspto.report (https://uspto.report/patent/grant/[5,693,429](/patent/5693429)).

• Line of business: National-defense research and development — a government laboratory, not a commercial vendor.
• Products embodying the claims: The Army does not sell products. Its stated channel is 37 CFR 404 licensing. The Army gave public notice of its intent to license this very patent at 63 FR 9212 (Feb. 24, 1998) (https://www.govinfo.gov/content/pkg/FR-1998-02-24/html/98-4672.htm), and later granted Paratek Microwave, Inc. an exclusive license to the sibling ARL BSTO patent US 5,427,988 (2001 Federal Register notice above). Paratek — an operating tunable-dielectric/varactor company — is the entity that built commercial devices on this ARL technology line; it was later absorbed into the BlackBerry/Research In Motion RF business (the '429 forward-citation family runs heavily through Paratek/BlackBerry).
• Current status: Operating (it is a U.S. Government department, not a legal person that can be acquired or dissolved). Ownership of the patent ran to its anticipated expiration on 2015-01-20; status is "Expired – Fee Related."

Assignment timeline

No post-issuance recorded assignment was found — and no recorded assignment of any kind could be retrieved from the accessible sources for this patent. Google Patents' legal-events table for US 5,693,429 shows only: application filed (1996-05-13) → application granted (1997-12-02) → anticipated expiration (2015-01-20) → "Expired – Fee Related." There is no assignment, security agreement, merger, change-of-name, or license recordation event in that table.

This is the expected result for a U.S. Government-owned patent: title is typically taken by operation of law / employment obligation, and many agency-owned cases carry no separately recorded assignment at all, or a single inventor→Government recordation. The chain is a single link:

Inventors (ARL) → United States of America, as represented by the Secretary of the Army → (expired 2015-01-20, never transferred)

Because I could not verify the presence/absence of even a single inventor→Government recordation (no reel/frame retrievable), I am not asserting that a reel/frame exists. Per the constraint in the task: the honest finding is the patent record shows no post-issuance ownership transfer away from the original assignee.

Related rights events (licenses — not assignments; included for completeness because the Assignment Center groups license recordations separately from assignments):

No correspondent of record could be captured, because no assignment record was retrievable. I therefore make no recurring-correspondent finding — a single appearance would not be a finding anyway, and I have zero appearances.

Timeline diagram

timeline
    title Rights chain of US 5693429
    1995 : Parent case filed Jan 20
         : ARL inventors named
    1996 : Continuation filed May 13
    1997 : Patent issued Dec 2
         : Army owns title
    1998 : Army licensing notice Feb 24
    2001 : Army licenses sibling to Paratek
    2015 : Patent expires Jan 20
         : No title transfer ever recorded

NPE / troll-pattern signals

Aggregate: zero NPE signals present. The strongest "soft" observation is the Government→Paratek exclusive license (signal 7 shape), which I have explicitly declined to score as a finding because it is a 37 CFR 404 license with title retained by the licensor, not a transfer.

Verdict

Insufficient data — no post-issuance ownership transfer is recorded, so the only meaningful entry is the original (Government) ownership. The patent was filed by an Army Research Laboratory group in 1995, issued 1997-12-02 with title held by the United States as represented by the Secretary of the Army, was offered for licensing at 63 FR 9212 (1998-02-24) and later licensed (sibling patent, 2001) to operating company Paratek Microwave, Inc., then expired 2015-01-20 still in Government hands. None of the eight NPE signals is present on the evidence I could reach; accordingly this is not an NPE/troll chain — it is a government tech-transfer chain.

Verification link: https://assignmentcenter.uspto.gov/ → Patent Number → 5693429 (expect either no records or a single inventor→Government recordation; if a post-1997 assignment to any "…IP / Holdings / Licensing" LLC appears there, that would overturn this verdict and should be treated as the controlling evidence).

Residual uncertainty: Because I could not load the Assignment Center record table, I cannot affirmatively rule out a recorded license (Assignment Center files licenses under a separate conveyance type) or a single inventor-assignment recordation for which I have no reel/frame. I found no evidence of any post-issuance assignment, and I have not fabricated one to fill the gap.

I'll research each cited reference and confirm the citation set for US 5,693,429.

Let me pull the full text and claims of the single cited reference US 5,312,790, and verify the sibling Army patents that could also qualify as prior art.

Prior-Art Analysis — US 5,693,429 ("Electronically graded multilayer ferroelectric composites")

0. Method note and a key scoping point

You asked me to (a) search the USPTO database for the specific number 5693429 and (b) analyze "each patent citation" for it. Two clarifications before the analysis:

• I cannot open USPTO PatentCenter directly from this environment. The number-specific record I relied on is the Google Patents full-text record for US5693429A (https://patents.google.com/patent/US5693429/en), which mirrors the USPTO grant, corroborated by uspto.report/patent/grant/5,693,429. All fields below are for the exact number 5,693,429 — not 5,693,424, 5,693,429-adjacent publications, or the unrelated JP 5693429 B2 (Mitsubishi Heavy Industries motor control) identified in the prior litigation section.
• The set of "citations" on the face of this patent is exactly one patent. The Google Patents "Patent Citations (1)" / "Citations (1)" sections list only US 5,312,790 A. There are no cited non-patent literature (NPL) references and no cited foreign patent documents on the face of the '429.

⚠️ Do not confuse the two citation lists. The record also shows "Cited By (137)" (and a longer 286-entry variant). Those are forward citations — later patents (mostly Paratek Microwave / BlackBerry / Research In Motion) that cite the '429. Forward citations are not prior art against the '429. They must be excluded from a §102/§103 analysis of this patent.

So the entire on-face prior-art citation set is a single reference. I analyze it below, then add the "next-closest" Army sibling patents that are not cited on the face but are the most plausible additional §102 art.

1. The one cited reference

Brief description (as disclosed). A bulk ceramic ferroelectric composite having low dielectric constant, low loss tangent and high tunability. The composite consists essentially of Barium Strontium Titanate (BSTO) plus a low-dielectric-constant ceramic, the preferred embodiment being Ba₁₋ₓSrₓTiO₃–Al₂O₃ with x > 0.00 but ≤ 0.70, and a BSTO:Al₂O₃ weight ratio of about 99–40% : 1–60%. The material is characterized as usable in antenna systems.

Representative claim (claim 1 of '790):

"A ceramic ferroelectric composite material consisting essentially of Barium Strontium Titanate, said Barium Strontium Titanate represented as Ba₁₋ₓSrₓTiO₃, wherein x is greater than 0.0 but less than or equal to 0.70; and alumina; wherein said Barium Strontium Titanate and alumina are present in amounts to provide a composite having a low dielectric constant, low loss tangent and high tunability."

2. §102 anticipation analysis of US 5,312,790 against the '429 claims

Every claim of the '429 (1–16) requires the same structural core: a plurality of adjacent layers, with no air gaps, each layer a BSTO/oxide composite whose ratio differs layer-to-layer, laminated together into a graded-dielectric stack. US 5,312,790 discloses only a unitary, single-composition bulk material — it has no layers, no grading, and no lamination.

Element-by-element against independent claim 1:

Result: US 5,312,790 does not anticipate any claim of US 5,693,429 under §102. It lacks at least four claim-1 elements — the plurality of layers, the per-layer differing ratio, the no-air-gaps feature, and lamination. It is therefore not §102(a)/(b)/(e) anticipatory art for claims 1–16.

What it is good for:

• §102 sub-element art / §103 obviousness: it supplies the BSTO + Al₂O₃ material system recited in claims 1 and 7 (and 13). A §103 rejection would still need a second reference teaching the graded multilayer lamination (i.e., the very point of novelty of the '429).
• Written-description / enablement support for the specification (it is the incorporated-by-reference disclosure for the Al₂O₃ embodiment).

Critical-date nuance (dates matter for the statutory ground):

• '790 issued 1994-05-17; the '429's parent was filed 1995-01-20. That is less than one year before filing, so '790 is not a §102(b) statutory bar.
• It is available as §102(a) art (patented before the applicant's invention date) and/or as §102(e) art with an effective date of its 1993-06-09 filing date (it is "by another" because the two inventor sets are not identical, even though they overlap and share the Army as assignee).

3. "Next-closest" prior art NOT cited on the face (added for completeness)

Because the sole on-face citation is a same-assignee sibling, the genuinely closest additional references are the other Army BSTO-composite patents in the same 1993–1996 family (disclosed in the same research program, same lead inventor). None is cited on the '429 face, but each is a plausible §102(e) reference. I flag them because an examiner or challenger would likely reach for them.

Sources: Google Patents US5486491; the Federal Register licensing notices listing '491, '790 and '988 together (62 FR 4268, 1997-01-29, https://www.govinfo.gov/content/pkg/FR-1997-01-29/html/97-2136.htm ; and 00-23916, 2000-09-18), which confirm the trio are the same Army program.

Also note (not prior art): the '429's parent application Ser. No. 08/376,194 (filed 1995-01-20, now abandoned) is the priority application, not prior art. And the frequently-seen companion US 5,830,591 ("Multilayered ferroelectric composite waveguides," filed 1996-04-29, issued 1998-11-03) is a forward citation — later art, not prior art against the '429.

4. Bottom line

1. The complete on-face prior-art citation set for US 5,693,429 is a single reference: US 5,312,790 A. There are no cited NPL or foreign references on the face of the patent.
2. US 5,312,790 does not anticipate any of claims 1–16 under 35 U.S.C. §102. It discloses a single-composition, bulk BSTO–Al₂O₃ composite, whereas every '429 claim requires a graded plurality of laminated layers with differing BSTO:oxide ratios and no air gaps — limitations with no counterpart in '790. Its value is as §102(a)/(e) art for the composition sub-elements (BSTO + Al₂O₃ in claims 1 and 7/13) and as §103 support, not as an anticipatory reference.
3. The large "Cited By" list is not prior art — those are later patents citing the '429.
4. The closest additional art is the Army sibling family (US 5,486,491 and US 5,427,988). They broaden the disclosed oxide set to ZrO₂ and MgO and, in '988, use the identical x ≤ 0.75 BSTO range — but they too are bulk composites and likewise fail to anticipate the laminated graded structure.

Confidence / limitations. The bibliographic, claim, and citation-set data are taken from the authoritative full text of US5693429A (Google Patents) and cross-checked against uspto.report and the Federal Register licensing notices. I could not run a live USPTO PatentCenter "References Cited" (PTO-892) lookup, and I therefore state the citation set as reflected in the accessible record; if you need absolute certainty on the PTO-892 contents (e.g., any cited NPL), a direct PatentCenter "Patent Application Full-Text / References Cited" pull is the definitive check.

I'll research the prior-art landscape around US 5,693,429 before building the § 103 analysis.

Strong hits. Let me pull details on the most promising references.

Obviousness Analysis — US 5,693,429 under 35 U.S.C. § 103

Builds on the prior sections' claim chart, internal-consistency flags, and the verified litigation/PTAB null result. The key analytical consequence of those sections is this: the claims were never amended, never challenged, and the examiner cited only one reference on the face — so this § 103 analysis runs against the original issued claim text, with no prosecution history narrowing and no IPR estoppel to work around.

1. Governing framework and critical date

• Priority date / invention date: 1995-01-20 (parent Ser. No. 08/376,194; the '429 is a § 120 continuation of it). Pre-AIA § 103 applies (Graham v. John Deere Co., 383 U.S. 1 (1966); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), governs the motivation analysis as the current standard).
• § 103(c) note: Because the '429 and US 5,312,790 are both Army-owned and may share inventors, common ownership/inventorship is a real issue for art qualifying only under § 102(e)/(f)/(g) — addressed in § 8 below.
• PHOSITA: a ceramic/materials engineer or microwave engineer with an advanced degree and ~3–5 years in ferroelectric microwave ceramics and/or tape-cast multilayer ceramic (MLCC) processing — i.e., exactly the profile of the concurrently active ARL/Penn State ferroelectric-phase-shifter teams.
• § 103 is not limited to the art cited on the face of the patent (only US 5,312,790 was). The full field is open, as the earlier PTAB section noted.

2. The relevant prior art set

3. What the art as a whole suggested to a PHOSITA

Three independent, non-overlapping lines of art converged on the '429's structure before January 1995:

1. The material system was known and tunable — US 5,312,790's BSTO/alumina (and ZrO₂, MgO, SiO₂) composites, already described by the applicant as the source of its layer compositions.
2. The graded-multilayer solution to air/medium mismatch was known — US 2,854,668 (radome lens wall), US 5,528,254 (multilayer, successively decreasing ε′, laminated ceramic green tapes, for exactly this reflection-minimization purpose), and US 5,309,166 (taper to avoid internal reflections in a ferroelectric phase shifter).
3. The fabrication route was routine — tape casting + stacking + pressing + co-firing of differently composed ceramic tapes is the MLCC art.

4. Independent Claim 1 — element mapping and combinations

Ground A (claims 1–9): US 5,312,790 + US 5,528,254.
Both are in the antenna arts. '790 supplies the tunable, low-loss BSTO/oxide composite family in the exact ratio range the claims recite; '254 supplies the structural/architectural teaching of a laminated, graded-ε stack with monotonically varying mixing ratio, built from ceramic green tapes, for the sole stated purpose of reducing reflection at the air interface. Substituting the '790 composite system for the '254 illustration (ε′ = 2…288 organics/ceramics) yields claim 1 with no change in the principle of operation — the grading remains a graded impedance transformer. This is the paradigm KSR case: a combination of two known elements (a known composite material; a known graded-layer impedance-matching architecture) each performing its known function.

Ground B (claims 1–9): US 5,312,790 + US 2,854,668.
The 1958 radome patent is a § 102(b) reference that already teaches layering a high-ε core with surrounding layers of progressively lower ε′ decreasing away from the core, in a radiating structure, precisely to control phase/reflection behavior. It supplies the same "grade the dielectric to match into the surrounding medium" rationale as '254 and, being older and non-analogous-argument-proof (same field of endeavor: antennas/radomes), is a cleaner motivation reference.

5. Independent Claim 10 — the "adjusting material" genus

Claim 10 adds a third constituent — a low-ε, low-loss "adjusting material" — with each layer having a different ratio of the three.

• US 5,528,254 again supplies the express motivation: it teaches both a "two-component system" with a monotonically varying mixing ratio and lists Teflon (a polymer, ε′ = 2–4) and Al₂O₃ as layer materials — i.e., it explicitly contemplates incorporating a very low-ε polymer into a graded ceramic/polymer dielectric stack.
• WO 94/29234 / US 5,312,790's disclosure of silicon dioxide as a low-ε, low-loss oxide additive supports claim 11's "silica" alternative.
• The '429's own specification supplies the rationale against itself: for "impedance matching below the dielectric constant of alumina (ε′ = 9) … a BSTO/oxide system [integrated] into a suitable polymer such as epoxy or a low dielectric form of silica" is proposed — i.e., the claimed expedient is described as the known way to reach a lower ε′ endpoint.

Ground D (claims 10–16): US 5,312,790 + US 5,528,254 + polymer/silica–ceramic composite art. Motivation: extending the graded stack's low-ε endpoint down to or below air-side values is the natural completion of the gradient, and the art already used polymer (Teflon) and silica as low-ε phases.

6. Dependent claims — mapping and rationale

7. Motivation to combine — the articulated reasons

Under KSR and Graham, the record supports at least five independent, mutually reinforcing rationales:

1. Express problem statement in the art. US 5,528,254 opens with the reflection-coefficient equation and states that mismatch "is not technically desirable"; US 2,854,668 solves the identical problem for radomes. The '429's own background identifies "the dielectric mismatch of air (ε′=1) and … BSTO (ε′=3300)."
2. Express solution in the art. Both US 5,528,254 and US 2,854,668 prescribe the same remedy the '429 claims: multiple adjacent layers of progressively decreasing ε′, with the outermost layer approaching ε′ of air.
3. Same field, same device. All references are antenna/phase-shifter/radome art; US 5,309,166 shows the very problem (air gap, internal reflections) in a ferroelectric phase shifter and the taper remedy.
4. Known, compatible manufacturing technique. Green-tape lamination and co-firing of differently composed ceramic layers was the standard MLCC process (EP 0 200 200 B1), and the '429 admits tape casting "is used for fabrication of a variety of ceramic substrates and multilayer capacitors." A PHOSITA had both the capability and the expectation of success in making a laminated graded stack.
5. Predictable operation / no change in principle. Each layer performs its known function (higher ε′ near the ferroelectric; lower ε′ toward air), and the resulting stack operates as an ordinary graded impedance transformer. KSR holds that "the combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results."

8. Where the invalidity case is weak — honest counter-considerations

A rigorous § 103 opinion must flag these, and they are the patentee's best arguments:

1. The single closest reference may not be prior art at all. The DTIC/SPIE FGM paper (Feb. 1994) reads almost verbatim onto the '429's disclosure — it gives the same equation, the same ~200 °C/7,000 psi lamination, the same Al₂O₃-thinner-than-BSTO design, and identical sample data. But it appears to be the inventors' own work. Pre-AIA § 102(a)/(e) reach only matter "by others." If the SPIE paper's inventive entity is identical to the '429's seven inventors, it is not a § 102/§ 103 reference (it is also within the one-year grace period, so no § 102(b) bar). I could not verify the SPIE paper's author list or the DTIC report's author list in this session. This is the pivotal open question for any invalidity challenge. Note that even if unavailable as a reference, it remains powerful evidence of what a PHOSITA knew and of the "predictable results" question.
2. Common ownership (§ 103(c)). US 5,312,790 and the '429 are both Army-owned. Art qualifying only under § 102(e)/(f)/(g) is disqualified for § 103 purposes if it was commonly owned at the time of invention. Practically, the better route is the applicant's own specification admission in the '429 (which cites '790 and relies on it as the source of the composite) rather than § 102(e).
3. Non-tunable matching layers as an art-recognized norm. The '429 states: "Most matching layer schemes do not involve materials with any amount of tunability." A patentee can argue the art taught that matching layers should be low-loss, non-tunable dielectrics, and that putting a tunable ferroelectric in the matching layers runs against that preference (loss penalty). Rebuttal: US 5,312,790 expressly teaches that the same BSTO/oxide composites have low loss tangents with tunability, and the '429's Table 4 shows loss tangents of 0.0009–0.024 across composition — so the alleged prejudice is not supported by the art of record.
4. The unexpected-failure record cuts both ways, and mostly against the patentee. Table 3 shows Stacks #2 and #3 (60% and 100% alumina) warped. That could have supported an argument that cofiring a strongly graded stack was unpredictable — except that no claim requires a warp-free or crack-free body, so the observed failure does not distinguish the claims from the art.
5. "No air gaps" and "graded" preamble terms are structural/functional labels that the co-fired laminate inherently satisfies; they do not import a separate inventive step.
6. Secondary considerations. There is no evidence of nexus. The 137+ forward citations are to patents/applications (mostly the Paratek/BlackBerry tunable-dielectric line, e.g., US 6,377,142, "Voltage tunable laminated dielectric materials for microwave applications"), which reflects background-art use of the '429, not commercial success attributable to the claims. The Army's own FR licensing notices (63 FR 9212; 61 FR 36038; 65 FR 56297) show a licensing, not enforcement, posture (see the earlier Litigation section).

9. Date-verification flags (do not treat as confirmed)

• US 5,528,254 — issue date 1996-06-18 is confirmed; I did not verify its filing or priority date. For it to be § 102(e)/§ 103 art against the '429's 1995-01-20 effective date, it must have been filed before that date. A 1993–94 filing is plausible given the 1996 issue date, but this must be confirmed from the front page before relying on it. If it filed after 1995-01-20, it drops out as § 102(e) art (though it remains evidence of the art) and the Ground A combination must rest on US 2,854,668 + the general knowledge of graded dielectric matching instead.
• US 5,555,286 — filed 1994-06-15 / issued 1996-09-17 is taken from the CA 2164595 citing table; treat as probable pending front-page confirmation.
• US 5,309,166 and ADA277154 — grant/publication dates not confirmed in this session.
• US 2,854,668 (1958) is safely § 102(b).

10. Bottom line

Most likely to survive: claims 3–4 (constant-capacitance thickness design) if the FGM publication is disqualified as the inventors' own work, because the impedance-matching art (US 5,528,254; US 2,854,668) is directed to reflection matching rather than to equalizing per-layer capacitance to linearize the bias voltage profile across a tunable ferroelectric stack. That device-specific design insight is the closest thing to a non-obvious core in this patent. Every other limitation has a direct, date-qualified antecedent in the art identified above.

Recommended next art to pull: (i) the front pages of US 5,528,254, US 5,555,286 and US 5,309,166 to fix dates; (ii) the SPIE Vol. 2189 author list and any earlier (1992–93) ARL/Penn State publication on graded BSTO tape stacks; (iii) the specification of US 6,377,142 (Paratek) and its PCT counterpart EP 1 135 827 A1, which describe voltage-tunable laminated dielectric materials and may characterize the '429 as background — useful both as art and as an admission of the state of the art.

Uncertainty statement (required). This analysis relies on prior-art documents retrieved via web search, several of which are quoted only in excerpt. The most important open items are (1) whether the ARL FGM publications (SPIE Vol. 2189, Feb. 1994; DTIC ADA277154) are "by others" relative to the '429's seven-inventor entity — which I could not verify; (2) the filing/priority date of US 5,528,254, which I could not confirm; and (3) the exact dates and full text of US 5,555,286, US 5,309,166 and US 5,556,361's relevant portions. I have not seen the full file wrapper of US 08/376,194 or 08/647,260, and I could not access PTAB/ODP or CAFC dockets directly; consistent with the earlier sections, no post-grant proceeding appears to exist in which any claim of the '429 was construed or canceled. Where I have stated a motivation or a claim mapping, it is grounded in the quoted text of the references cited with URLs above; where I lack a verified date or author list, I have said so rather than assume one.