An electromagnetic metamaterial patent claims a structure engineered to manipulate radio-frequency or microwave energy — typically for antenna gain, radar cross-section reduction or electromagnetic cloaking — and is classified under IPC codes like H01Q (antennas) or H01P (waveguides). An acoustic metamaterial patent instead claims structures engineered to manipulate sound waves, for noise control, vibration damping or soundproofing, classified under G10K. In this dataset the two traditions are not evenly split: acoustic applications (430 of 696 records) substantially outnumber electromagnetic ones (266), so most of the crowded prior art sits on the acoustics side. The two claim types cite different prior art and are prosecuted by largely different assignee pools, so a filer working in one rarely competes directly with filers in the other.

The dataset's strongest collaboration is between two affiliated Chinese research institutes that jointly hold 32 shared patent families, the largest co-assignee link in the corpus. A separate pairing links a French national research center with a French university on 10 shared families. Beyond these leading groups, filing activity has a long tail of single-institution and single-inventor filers, and notably, none of the top-ranked assignees tracked for recent-year momentum show any filings in the most recent tracked year — the whole field's filing pace has cooled, not just any one company's.

Filing volume rose from 16 records in 2017 to a peak of 85 in 2023, then declined toward the 2026 cut-off, with the 2022 midpoint sitting at 61. Because patent publication typically lags filing by around 18 months, the most recent one to two years will revise upward as pending applications publish, so the apparent decline is somewhat overstated. Even accounting for that lag, the trend from 2022 onward reads as flat-to-declining rather than accelerating, suggesting the initial wave of foundational filing in this space has already passed its peak.

The clearest gaps sit outside the two dominant classes. G10K acoustics and H01Q antennas together account for the large majority of the 696 tracked records, while IPC classes covering HVAC integration (F24F), power and grid systems (H02J), radar and positioning (G01S), and waveguide/microwave elements (H01P) each hold only single-digit-percentage shares. These adjacent applications use the same underlying metamaterial physics but have not attracted the same volume of claims, which makes them a more realistic entry point for a new filer than trying to draft around the dense acoustics or antenna prior art directly.

376 of the 696 tracked records were filed at the China receiving office, more than three times the United States total of 120 and well ahead of the EPO's 59, WIPO's 39 (PCT), India's 37 and South Korea's 28. This concentration reflects where the leading research-affiliated assignees in this dataset are based, including the two Chinese institutes behind the strongest co-assignee pairing in the corpus. For competitive intelligence or clearance purposes, this means a search strategy that starts with USPTO or EPO prior art and treats China as an afterthought will miss the majority of relevant filings in this field.