{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T12:46:44Z","timestamp":1785761204415,"version":"3.56.0"},"reference-count":27,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T00:00:00Z","timestamp":1785542400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Small multi-rotor UAVs are difficult radar targets: their radar cross-section is low and aspect-dependent, and their slow body motion overlaps with birds and clutter in Doppler processing. We address W-band (94 GHz) detection with a physics-informed, non-coherent framework that exploits blade flexibility. A compact three-dimensional micro-Doppler model combines counter-rotating rotor kinematics, hub-dependent spatial phase, and a first-order out-of-plane bending term; the rigid rotational signature scales with cos\u03b2 and the bending contribution with sin\u03b2 in elevation \u03b2. Near zenith, where rigid micro-Doppler collapses toward DC, bending repopulates an observable low-velocity band. Detection uses cosine similarity between magnitude spectrograms, which is robust to the tested oscillator impairments. With a calibrated false-alarm rate (PFA=0.01) and unknown target rotor phase, the detector reaches Pd\u22480.9 at SNR \u2248\u221214 dB and stays stable for carrier-frequency offsets up to 500 Hz and phase random walk up to 0.2\u00a0rad\/sample, where an uncompensated matched filter fails; it also retains detection against simulated bird-and-clutter micro-Doppler in the background-dominated regime where an energy detector collapses. A consistency check against measured single-blade no-IQ W-band records reproduces the one-sided time\u2013frequency periodicity under a matched product-detector operator. The result is an interpretable, training-free baseline for phase-limited W-band UAV sensing.<\/jats:p>","DOI":"10.3390\/s26154851","type":"journal-article","created":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T11:50:21Z","timestamp":1785757821000},"page":"4851","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Bending-Aware Spectrogram Correlation for W-Band Quadcopter Detection: A Physics-Informed Non-Coherent Detection Framework"],"prefix":"10.3390","volume":"26","author":[{"given":"Yael","family":"Balal","sequence":"first","affiliation":[{"name":"Department of Electrical and Electronics Engineering, Afeka College of Engineering, Tel Aviv 6910717, Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Natan","family":"Steinmetz","sequence":"additional","affiliation":[{"name":"Department of Electrical and Electronics Engineering, Ariel University, Ariel 4076414, Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arie","family":"Sherenzon","sequence":"additional","affiliation":[{"name":"Department of Electrical and Electronics Engineering, Ariel University, Ariel 4076414, Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4382-4053","authenticated-orcid":false,"given":"Nezah","family":"Balal","sequence":"additional","affiliation":[{"name":"Department of Electrical and Electronics Engineering, Ariel University, Ariel 4076414, Israel"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1049\/iet-rsn.2016.0063","article-title":"Multistatic micro-Doppler radar feature extraction for classification of unloaded\/loaded micro-drones","volume":"11","author":"Ritchie","year":"2017","journal-title":"IET Radar Sonar Navig."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"17396","DOI":"10.1038\/s41598-018-35880-9","article-title":"Radar micro-Doppler signatures of drones and birds at K-band and W-band","volume":"8","author":"Rahman","year":"2018","journal-title":"Sci. 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