Notch antennas, also known as the tapered slot antennas (TSA), have been the topics of research for decades. TSA has demonstrated multioctave bandwidth, moderate gain (7–10 dB), and symmetric
E
‐ and
H
‐plane beam patterns and can be used for many different applications. This article summarizes the research activities on notch antennas over the since the early 1990s with emphasis on their most recent advances and applications. The article begins with some discussions on the design of single TSA, then follows with detailed discussions of issues associated with TSA designs and performance characteristics. To conclude the article, some recent developments in TSA arrays and their applications are highlighted.