The leading assignee in this dataset holds 129 records, with the field then dropping to 63 at fifth place and 61 at tenth. The top 5 assignees combined account for only 8.3% of the 5,186 records in scope, and the top 10 combined reach 14.2%. That distribution means the field is led but not dominated by any one company, and freedom-to-operate risk is spread across a long tail of moderate-volume filers rather than concentrated in a single blocker.

Filing peaked in 2017 at 147 records and has since stepped down: comparing the last two complete years available, 2021’s 88 filings fell to 55 in 2024, a 38% decline. Figures for 2025 and 2026 are still incomplete because publication typically lags actual filing by around 18 months, so the most recent years in any chart will always look lower than they eventually turn out to be. Read the 2021–2024 comparison as the reliable trend, not the final two bars.

In this corpus, ‘tunable’ filings typically claim continuous adjustment of a parameter like centre frequency using a mechanism such as a ferroelectric varactor, while ‘reconfigurable’ filings, including the representative record US9705542B2, more often claim discrete switching between defined operating modes, for example different bandwidth and insertion-loss states via a resonator and coupling circuit. Switched filter banks sit closer to the reconfigurable end since they select among fixed filter paths rather than continuously tuning one. The practical distinction matters for claim drafting: continuous tuning claims tend to focus on tuning range and linearity, while mode-switching claims focus on the switching mechanism and settling time.