hi,

its good to know your zest for isro, however there is no surety that in 2021 isro will conduct recruitment for scientist/ engineers or not. see eee students may apply for isro from ece branch or ee branch, however for ee branch recruitment is quite less, 2-3 vacancies as per latest notifications, now you may also appear from ece but you need to study be self for some papers like digital communications, signal system, antenna theory etc. syllabus and question pattern is like gate, so if you have good grip on gate syllabus, you may surely crack it.