Metal crack size recognizing used circular patch antenna Hanalde Andre, Teguh Putra Trila Seyepa, Amirul Luthfi, Ridho Aidil Fitrah, Toha Zaky and Rizda Azri Ramlee E3S Web Conf., 464 (2023) 01017 Published online: 18 December 2023 DOI: 10.1051/e3sconf/202346401017