{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,28]],"date-time":"2025-10-28T05:52:17Z","timestamp":1761630737788,"version":"build-2065373602"},"reference-count":36,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2015,11,17]],"date-time":"2015-11-17T00:00:00Z","timestamp":1447718400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Spanish Ministry of Economy and Competitiveness","award":["TEC2012\/38701"],"award-info":[{"award-number":["TEC2012\/38701"]}]},{"DOI":"10.13039\/501100006302","name":"University of Alcal\u00e1","doi-asserted-by":"publisher","award":["CCG2014\/EXP060"],"award-info":[{"award-number":["CCG2014\/EXP060"]}],"id":[{"id":"10.13039\/501100006302","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Passive radars exploit the signal transmitted by other systems, known as opportunity illuminators (OIs), instead of using their own transmitter. Due to its almost total invulnerability to natural disasters or physical attacks, satellite OIs are of special interest. In this line, a feasibility study of Earth Observation Synthetic Aperture Radar (EO SAR) systems as OIs is carried out taking into consideration signal waveform, availability, bistatic geometry, instrumented coverage area and incident power density. A case study based on the use of PAZ, the first Spanish EO SAR, is presented. PAZ transmitted waveform, operation modes, orbit characteristics and antenna and transmitter parameters are analyzed to estimate potential coverages and resolutions. The study concludes that, due to its working in on-demand operating mode, passive radars based on PAZ-type illuminators can be proposed as complementing tools during the sensor commissioning phase, for system maintenance and for improving its performance by providing additional information about the area of interest and\/or increasing the data updating speed, exploiting other sensors during the time PAZ is not available.<\/jats:p>","DOI":"10.3390\/s151129079","type":"journal-article","created":{"date-parts":[[2015,11,17]],"date-time":"2015-11-17T10:23:41Z","timestamp":1447755821000},"page":"29079-29106","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Feasibility Study of EO SARs as Opportunity Illuminators in Passive Radars: PAZ-Based Case Study"],"prefix":"10.3390","volume":"15","author":[{"given":"Jose-Luis","family":"B\u00e1rcena-Humanes","sequence":"first","affiliation":[{"name":"Signal Theory and Communications Department, Higher Polytechnic School, University of Alcal\u00e1, Alcal\u00e1 de Henares, Madrid 28805, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pedro-Jos\u00e9","family":"G\u00f3mez-Hoyo","sequence":"additional","affiliation":[{"name":"Signal Theory and Communications Department, Higher Polytechnic School, University of Alcal\u00e1, Alcal\u00e1 de Henares, Madrid 28805, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maria-Pilar","family":"Jarabo-Amores","sequence":"additional","affiliation":[{"name":"Signal Theory and Communications Department, Higher Polytechnic School, University of Alcal\u00e1, Alcal\u00e1 de Henares, Madrid 28805, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David","family":"Mata-Moya","sequence":"additional","affiliation":[{"name":"Signal Theory and Communications Department, Higher Polytechnic School, University of Alcal\u00e1, Alcal\u00e1 de Henares, Madrid 28805, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nerea","family":"Del-Rey-Maestre","sequence":"additional","affiliation":[{"name":"Signal Theory and Communications Department, Higher Polytechnic School, University of Alcal\u00e1, Alcal\u00e1 de Henares, Madrid 28805, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,11,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Willis, N.J. 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