{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:44:05Z","timestamp":1760237045980,"version":"build-2065373602"},"reference-count":10,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2020,2,20]],"date-time":"2020-02-20T00:00:00Z","timestamp":1582156800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"undefined  &lt;span style=&quot;color:gray;font-size:10px;&quot;&gt;undefined&lt;\/span&gt;","award":["2016YFE0200400"],"award-info":[{"award-number":["2016YFE0200400"]}]},{"name":"National Key R&amp;D Program of China","award":["2016YFE0200400"],"award-info":[{"award-number":["2016YFE0200400"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>It is a challenge to realize wide swath imaging due to the conflict between Doppler ambiguity and range ambiguity for hypersonic vehicle (HSV) radar. In addition, there are many conditions requiring the forward-looking imaging. In a forward-looking synthetic aperture radar (SAR) system, left\u2013right ambiguity arises, since two symmetrical targets have the same Doppler frequency magnitude. After selecting an appropriate pulse repetition frequency (PRF) to avoid Doppler ambiguity, we only need to solve the range ambiguity and left\u2013right ambiguity. To handle these issues, this paper proposes an approach to resolve the range ambiguity and left\u2013right ambiguity using the frequency diverse array (FDA). With the range-angle-dependent property of the transmit steering vector, FDA can distinguish the range ambiguous echoes in the spatial frequency domain. By performing transmit beamforming after range compensation, the echo from the desired range region can be extracted from ambiguous echoes. Then, the back projection (BP) algorithm is used to achieve imaging. Next, the echoes of all channels are processed by two receive beamformers, which are designed for the right and left sides, respectively. With the aforementioned procedures, an unambiguous image can be obtained. Simulation results have verified the effectiveness of the proposed approach.<\/jats:p>","DOI":"10.3390\/s20041169","type":"journal-article","created":{"date-parts":[[2020,2,21]],"date-time":"2020-02-21T10:49:16Z","timestamp":1582282156000},"page":"1169","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Unambiguous Forward-Looking SAR Imaging on HSV-R Using Frequency Diverse Array"],"prefix":"10.3390","volume":"20","author":[{"given":"Mengdi","family":"Zhang","sequence":"first","affiliation":[{"name":"National Lab of Radar Signal Processing, Xidian University, Xi\u2019an 710071, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guisheng","family":"Liao","sequence":"additional","affiliation":[{"name":"National Lab of Radar Signal Processing, Xidian University, Xi\u2019an 710071, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiongpeng","family":"He","sequence":"additional","affiliation":[{"name":"National Lab of Radar Signal Processing, Xidian University, Xi\u2019an 710071, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shengqi","family":"Zhu","sequence":"additional","affiliation":[{"name":"National Lab of Radar Signal Processing, Xidian University, Xi\u2019an 710071, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,2,20]]},"reference":[{"key":"ref_1","first-page":"80","article-title":"Research of Radar Clutter Characteristics on Hypersonic Vehicle","volume":"35","author":"Li","year":"2013","journal-title":"Modern Radar"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Antonik, P., Wicks, M.C., Griffiths, H.D., and Baker, C.J. (2006, January 22\u201327). Range-dependent beamforming using element level waveform diversity. Proceedings of the 2006 International Waveform Diversity & Design Conference, Lihue, HI, USA.","DOI":"10.1109\/WDD.2006.8321488"},{"key":"ref_3","unstructured":"Antonik, P., Wicks, M.C., Griffiths, H.D., and Baker, C.J. (2006, January 24\u201327). Frequency diverse array radars. Proceedings of the 2006 IEEE Conference on Radar, Verona, NY, USA."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Secmen, M., Demir, S., Hizal, A., and Eker, T. (2007, January 17\u201320). Frequency Diverse Array Antenna with Periodic Time Modulated Pattern in Range and Angle. Proceedings of the 2007 IEEE Radar Conference, Boston, MA, USA.","DOI":"10.1109\/RADAR.2007.374254"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"4073","DOI":"10.1109\/TAP.2013.2260515","article-title":"Range-Angle Dependent Transmit Beampattern Synthesis for Linear Frequency Diverse Arrays","volume":"61","author":"Wang","year":"2013","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Zhu, Y., Wang, H., Zhang, S., Zheng, Z., and Wang, W. (2018, January 22\u201327). Deceptive Jamming on Space-Borne Sar Using Frequency Diverse Array. Proceedings of the IGARSS 2018\u20132018 IEEE International Geoscience and Remote Sensing Symposium, Valencia, Spain.","DOI":"10.1109\/IGARSS.2018.8518451"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1620","DOI":"10.1109\/JSTSP.2015.2465353","article-title":"Range Ambiguous Clutter Suppression for Airborne FDA-STAP Radar","volume":"9","author":"Xu","year":"2015","journal-title":"IEEE J. Sel. Top. Signal Process."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1628","DOI":"10.1109\/LGRS.2017.2727512","article-title":"Unambiguous Signal Reconstruction Approach for SAR Imaging Using Frequency Diverse Array","volume":"14","author":"Lin","year":"2017","journal-title":"IEEE Geosci. and Remote Sens. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1543","DOI":"10.1109\/JSTARS.2015.2507260","article-title":"A New Imaging Algorithm for Forward-Looking Missile-Borne Bistatic SAR","volume":"9","author":"Chen","year":"2016","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2857","DOI":"10.3724\/SP.J.1146.2013.00083","article-title":"Study on deambiguity algorithm for double antenna forward looking missile borne SAR","volume":"35","author":"Bao","year":"2013","journal-title":"J. Electron. Inf. Technol."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/4\/1169\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T08:59:28Z","timestamp":1760173168000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/4\/1169"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,2,20]]},"references-count":10,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2020,2]]}},"alternative-id":["s20041169"],"URL":"https:\/\/doi.org\/10.3390\/s20041169","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2020,2,20]]}}}