{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,24]],"date-time":"2026-01-24T01:34:09Z","timestamp":1769218449610,"version":"3.49.0"},"reference-count":23,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2023,8,17]],"date-time":"2023-08-17T00:00:00Z","timestamp":1692230400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>Symmetry in designing a microstrip coupler is crucial because it ensures balanced power division and minimizes unwanted coupling between the coupled lines. In this paper, a filtering branch-line coupler (BLC) with a simple symmetrical microstrip structure was designed, analyzed and fabricated. Based on a mathematical design procedure, the operating frequency was set at 5.2 GHz for WLAN and 5G applications. Moreover, an optimization method was used to improve the performance of the proposed design. It occupied an area of 83.2 mm2. Its harmonics were suppressed up to 15.5 GHz with a maximum level of \u221215 dB. Meanwhile, the isolation was better than \u221228 dB. Another advantage of this design was its high phase balance, where the phase difference between its output ports was 270\u00b0 \u00b1 0.1\u00b0. To verify the design method and simulation results, the proposed coupler was fabricated and measured. The results show that all the simulation, design methods, and experimental results are in good agreement. Therefore, the proposed design can be easily used in designing high-performance microstrip-based communication systems.<\/jats:p>","DOI":"10.3390\/sym15081598","type":"journal-article","created":{"date-parts":[[2023,8,17]],"date-time":"2023-08-17T10:42:29Z","timestamp":1692268949000},"page":"1598","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["A Balanced Symmetrical Branch-Line Microstrip Coupler for 5G Applications"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2724-5118","authenticated-orcid":false,"given":"Salah","family":"Yahya","sequence":"first","affiliation":[{"name":"Department of Communication and Computer Engineering, Cihan University-Erbil, Erbil 44001, Iraq"},{"name":"Department of Software Engineering, Faculty of Engineering, Koya University, Koya KOY45, Iraq"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8434-166X","authenticated-orcid":false,"given":"Farid","family":"Zubir","sequence":"additional","affiliation":[{"name":"Wireless Communication Centre, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310, Johor, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4034-9437","authenticated-orcid":false,"given":"Leila","family":"Nouri","sequence":"additional","affiliation":[{"name":"Institute of Research and Development, Duy Tan University, Da Nang 50000, Vietnam"},{"name":"School of Engineering & Technology, Duy Tan University, Da Nang 50000, Vietnam"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9925-673X","authenticated-orcid":false,"given":"Fawwaz","family":"Hazzazi","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, College of Engineering in Al-Kharj, Prince Sattam bin Abdulaziz University, Al-Kharj 11492, Saudi Arabia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0564-238X","authenticated-orcid":false,"given":"Zubaida","family":"Yusoff","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Multimedia University, Persiaran Multimedia, Cyberjaya 63100, Selangor, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6063-3377","authenticated-orcid":false,"given":"Muhammad","family":"Chaudhary","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Ajman University, Ajman P.O. Box 346, United Arab Emirates"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1584-8747","authenticated-orcid":false,"given":"Maher","family":"Assaad","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Ajman University, Ajman P.O. Box 346, United Arab Emirates"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0642-6726","authenticated-orcid":false,"given":"Abbas","family":"Rezaei","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Kermanshah University of Technology, Kermanshah 67146, Iran"}]},{"given":"Binh","family":"Nguyen Le","sequence":"additional","affiliation":[{"name":"Institute of Research and Development, Duy Tan University, Da Nang 50000, Vietnam"},{"name":"School of Engineering & Technology, Duy Tan University, Da Nang 50000, Vietnam"}]}],"member":"1968","published-online":{"date-parts":[[2023,8,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Jameel, M.S., Mezaal, Y.S., and Atilla, D.C. (2023). Miniaturized Coplanar Waveguide-Fed UWB Antenna for Wireless Applications. Symmetry, 15.","DOI":"10.3390\/sym15030633"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Wang, Z., You, W., Yang, M., Nie, W., and Mu, W. (2023). Design of MIMO Antenna with Double L-Shaped Structure for 5G NR. Symmetry, 15.","DOI":"10.3390\/sym15030579"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Roshani, S., Yahya, S.I., Rastad, J., Mezaal, Y.S., Liu, L.W.Y., and Roshani, S. (2022). Design of a Filtering Power Divider with Simple Symmetric Structure Using Stubs. Symmetry, 14.","DOI":"10.3390\/sym14101973"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Jamshidi, M., Yahya, S.I., Nouri, L., Hashemi-Dezaki, H., Rezaei, A., and Chaudhary, M.A. (2023). A High-Efficiency Diplexer for Sustainable 5G-Enabled IoT in Metaverse Transportation System and Smart Grids. Symmetry, 15.","DOI":"10.3390\/sym15040821"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2110","DOI":"10.1002\/mop.28552","article-title":"Novel 2.4 GHz branch-line coupler using microstrip cells","volume":"56","author":"Salehi","year":"2014","journal-title":"Microw. Opt. Technol. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"704","DOI":"10.1109\/TMTT.2005.862657","article-title":"Compact Wide-Band Branch-Line Hybrids","volume":"54","author":"Chun","year":"2006","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1587\/elex.8.736","article-title":"Miniaturization and Harmonic Suppression of the Branch-Line Coupler Based on Radial Stubs","volume":"8","author":"Hazeri","year":"2011","journal-title":"IEICE Electron. Express"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1109\/LMWC.2007.899307","article-title":"A Compact Slow-Wave Microstrip Branch-Line Coupler with High Performance","volume":"17","author":"Wang","year":"2007","journal-title":"IEEE Microw. Wirel. Comp. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1007\/s11277-015-3138-z","article-title":"Enhanced Design of Two-Section Microstrip-Slot Branch Line Coupler with the Overlapped k\/4 Open Circuited Lines at Ports","volume":"88","author":"Shukor","year":"2016","journal-title":"Springer Wirel. Pers. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Santiko, A.B., Saputera, Y.P., and Wahyu, Y. (2016, January 25\u201327). Design and Implementation of Three Branch Line Coupler at 3.0 GHz Frequency for S-Band Radar System. Proceedings of the 22nd Asia-Pacific Conference on Communications (APCC), Yogyakarta, Indonesia.","DOI":"10.1109\/APCC.2016.7581487"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1369","DOI":"10.1002\/mop.29798","article-title":"Compact Microstrip Branch-Line Coupler with Wideband Quadrture Phase Balance","volume":"58","author":"Velan","year":"2016","journal-title":"Microw. Opt. Technol. Lett."},{"key":"ref_12","first-page":"264","article-title":"Novel Enhanced and Miniaturized 90\u00b0 Coupler for 3G EH Mixers","volume":"3","author":"Shamsinejad","year":"2008","journal-title":"IEEE Microw. Millim. Wave Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1081","DOI":"10.1002\/mop.29025","article-title":"Novel tunable branch-line coupler for WLAN applications","volume":"57","author":"Salehi","year":"2015","journal-title":"Microw. Opt. Technol. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1109\/LMWC.2009.2031998","article-title":"A Novel Triple-Band Microstrip Branch-Line Coupler with Arbitrary Operating Frequencies","volume":"19","author":"Liou","year":"2009","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_15","first-page":"16115","article-title":"5G planar branch line coupler design based on the analysis of dielectric constant, loss tangent and quality factor at high frequency","volume":"10","author":"Shukor","year":"2020","journal-title":"Nat. Sci. Rep."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1590\/2179-10742018v17i11121","article-title":"Microstrip Hybrid Coupler with a Wide Stop-Band Using Symmetric Structure for Wireless Applications","volume":"17","author":"Rezaei","year":"2018","journal-title":"J. Microw. Optoelectron. Electromagn. Appl."},{"key":"ref_17","first-page":"1346","article-title":"New design of wideband microstrip branch line coupler using T-shape and open stub for 5G application","volume":"11","author":"Abdulbari","year":"2021","journal-title":"Int. J. Electr. Comput. Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1109\/LMWC.2016.2516764","article-title":"A Balanced Filtering Branch-Line Coupler","volume":"26","author":"Shi","year":"2016","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Nouri, L., Yahya, S.I., and Rezaei, A. (2023). Design and Fabrication of a Compact Branch-Line Hybrid Coupler with a Balanced Phase Using a New Microstrip Structure for GSM Applications. AEU-Int. J. Electron. Commun., 161.","DOI":"10.1016\/j.aeue.2023.154529"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1109\/LMWC.2011.2138687","article-title":"Wideband 3 dB Branch Line Coupler Based on \u03bb\/4 Open Circuited Coupled Lines","volume":"21","author":"Arriola","year":"2011","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1007\/s10470-018-1255-9","article-title":"Novel microstrip branch-line coupler with low phase shift for WLANs","volume":"98","author":"Rezaei","year":"2019","journal-title":"Analog. Integr. Circuits Signal Process."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Hong, J.S., and Lancaster, M.J. (2001). Microstrip Filters for RF\/Microwave Applications, John Wiley & Sons.","DOI":"10.1002\/0471221619"},{"key":"ref_23","first-page":"1","article-title":"A New Design Approach for a Compact Microstrip Diplexer with Good Passband Characteristics","volume":"10","author":"Rezaei","year":"2022","journal-title":"ARO-Sci. J. Koya Univ."}],"container-title":["Symmetry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-8994\/15\/8\/1598\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:36:14Z","timestamp":1760128574000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-8994\/15\/8\/1598"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,8,17]]},"references-count":23,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2023,8]]}},"alternative-id":["sym15081598"],"URL":"https:\/\/doi.org\/10.3390\/sym15081598","relation":{},"ISSN":["2073-8994"],"issn-type":[{"value":"2073-8994","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,8,17]]}}}