{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T18:24:00Z","timestamp":1785435840485,"version":"3.56.0"},"reference-count":27,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,19]],"date-time":"2026-07-19T00:00:00Z","timestamp":1784419200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010877","name":"Shenzhen Science and Technology Innovation Commission","doi-asserted-by":"publisher","award":["JCYJ20210324120002007"],"award-info":[{"award-number":["JCYJ20210324120002007"]}],"id":[{"id":"10.13039\/501100010877","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100010877","name":"Shenzhen Science and Technology Innovation Commission","doi-asserted-by":"publisher","award":["KJZD20230923115216034"],"award-info":[{"award-number":["KJZD20230923115216034"]}],"id":[{"id":"10.13039\/501100010877","id-type":"DOI","asserted-by":"publisher"}]},{"award":["JCYJ20210324120002007"],"award-info":[{"award-number":["JCYJ20210324120002007"]}],"id":[{"id":"https:\/\/ror.org\/017n8df75","id-type":"ROR","asserted-by":"publisher"}]},{"award":["KJZD20230923115216034"],"award-info":[{"award-number":["KJZD20230923115216034"]}],"id":[{"id":"https:\/\/ror.org\/017n8df75","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100007162","name":"Guangdong Department of Science and Technology","doi-asserted-by":"publisher","award":["2023B1212060024"],"award-info":[{"award-number":["2023B1212060024"]}],"id":[{"id":"10.13039\/501100007162","id-type":"DOI","asserted-by":"publisher"}]},{"award":["2023B1212060024"],"award-info":[{"award-number":["2023B1212060024"]}],"id":[{"id":"https:\/\/ror.org\/00tjzgn92","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Laboratory of Operation and Application in Electromagnetic Domain","award":["CETCKL20230010"],"award-info":[{"award-number":["CETCKL20230010"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Micro-Unmanned Aerial Vehicles (micro-UAVs) require compact radar arrays under severe Size, Weight, Power, and Cost (SWaP-C) constraints. Spread Spectrum Digital Beamforming (SSDBF) reduces receiver hardware by multiplexing multiple antenna channels before a shared RF chain, but the receiver-side switching operation folds wideband noise and injects switch-related transient noise before digital demultiplexing. This paper develops a hardware-waveform co-design framework that links the transition density of bipolar spreading sequences to high-frequency code energy and switching-event count, while explicitly distinguishing modulation-induced thermal-noise folding from switch-transient injection. Transition density is used as a physically interpretable design surrogate rather than a sufficient statistic for folded noise, and it is constrained jointly with non-zero-shift cross-correlation to preserve spatial isolation under receiver-side timing skew. An \u03f5-constrained Greedy Coordinate Space Search (\u03f5-GCSS) algorithm is proposed to synthesize low-transition-density SSDBF code sets. Commercial circuit-level transient simulations and system-level MATLAB R2024b simulations show that the proposed code set reduces the PRN-like transition-density level from about 0.50 to about 0.19, lowers the circuit-simulation-derived integrated IF noise power by 9.63 dB relative to the Gold\/PRN-like baseline, and improves the normalized maximum detection range by 8.2 percentage points at K=4 without adding analog front-end hardware.<\/jats:p>","DOI":"10.3390\/s26144574","type":"journal-article","created":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T07:54:13Z","timestamp":1784534053000},"page":"4574","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["System-Level Hardware-Waveform Co-Design for Micro-UAV Radar Sensors: Suppressing Noise Folding in Extreme SWaP-C SSDBF Arrays"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-9918-2359","authenticated-orcid":false,"given":"Xinhua","family":"Dai","sequence":"first","affiliation":[{"name":"School of Electronics and Communication Engineering, Sun Yat-sen University, Shenzhen Campus, No. 66 Gongchang Road, Guangming District, Shenzhen 518107, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kai","family":"Xie","sequence":"additional","affiliation":[{"name":"School of Electronics and Communication Engineering, Sun Yat-sen University, Shenzhen Campus, No. 66 Gongchang Road, Guangming District, Shenzhen 518107, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Youkang","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Electronics and Communication Engineering, Sun Yat-sen University, Shenzhen Campus, No. 66 Gongchang Road, Guangming District, Shenzhen 518107, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1109\/MCE.2021.3063945","article-title":"Architecture, Classification, and Applications of Contemporary Unmanned Aerial Vehicles","volume":"10","author":"Alghamdi","year":"2021","journal-title":"IEEE Consum. 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