{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,7]],"date-time":"2026-05-07T15:45:52Z","timestamp":1778168752300,"version":"3.51.4"},"reference-count":32,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2021,11,30]],"date-time":"2021-11-30T00:00:00Z","timestamp":1638230400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100017580","name":"National Education and Research Network","doi-asserted-by":"publisher","award":["01245.010604\/2020-14"],"award-info":[{"award-number":["01245.010604\/2020-14"]}],"id":[{"id":"10.13039\/100017580","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003593","name":"National Council for Scientific and Technological Development","doi-asserted-by":"publisher","award":["429496\/2018-4"],"award-info":[{"award-number":["429496\/2018-4"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003593","name":"National Council for Scientific and Technological Development","doi-asserted-by":"publisher","award":["305958\/2018-6"],"award-info":[{"award-number":["305958\/2018-6"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We demonstrate a concept for a large enhancement of the directivity and gain of readily available cm- and mm-wave antennas, i.e., without altering any property of the antenna design. Our concept exploits the high reflectivity of a Bragg reflector composed of three bilayers made of transparent materials. The cavity has a triangular aperture in order to resemble the idea of a horn-like, highly directive antenna. Importantly, we report gain enhancements of more than 400% in relation to the gain of the antenna without the Bragg structure, accompanied by a highly directive radiation pattern. The proposed structure is cost-effective and easy to fabricate with 3D-printing. Our results are presented for frequencies within the conventional WiFi frequencies, based on IEEE 802.11 standards, thus, enabling easily implementation by non-experts and needing only to be placed around the antenna to improve the directivity and gain of the signal.<\/jats:p>","DOI":"10.3390\/s21238014","type":"journal-article","created":{"date-parts":[[2021,12,1]],"date-time":"2021-12-01T01:45:02Z","timestamp":1638323102000},"page":"8014","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["3D-Printed Quasi-Cylindrical Bragg Reflector to Boost the Gain and Directivity of cm- and mm-Wave Antennas"],"prefix":"10.3390","volume":"21","author":[{"given":"J\u00e9ssica A. P.","family":"Ribeiro","sequence":"first","affiliation":[{"name":"National Institute of Telecommunications (Inatel), Santa Rita do Sapuca\u00ed 37540-000, MG, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hugo R. D.","family":"Filgueiras","sequence":"additional","affiliation":[{"name":"National Institute of Telecommunications (Inatel), Santa Rita do Sapuca\u00ed 37540-000, MG, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5659-4165","authenticated-orcid":false,"given":"Arismar","family":"Cerqueira Sodr\u00e9 Junior","sequence":"additional","affiliation":[{"name":"National Institute of Telecommunications (Inatel), Santa Rita do Sapuca\u00ed 37540-000, MG, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3800-398X","authenticated-orcid":false,"given":"Felipe","family":"Beltr\u00e1n-Mej\u00eda","sequence":"additional","affiliation":[{"name":"Padtec, Campinas 13098-396, SP, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1742-9957","authenticated-orcid":false,"given":"Jorge Ricardo","family":"Mej\u00eda-Salazar","sequence":"additional","affiliation":[{"name":"National Institute of Telecommunications (Inatel), Santa Rita do Sapuca\u00ed 37540-000, MG, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1109\/MCOM.2014.6736750","article-title":"Millimeter-Wave Beamforming as an Enabling Technology for 5G Cellular Communications: Theoretical Feasibility and Prototype Results","volume":"52","author":"Roh","year":"2014","journal-title":"IEEE Commun. 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