“…In particular, for the spiral balun, it shows comparable AI and PI with of the presented approaches (e.g., [65] and [70]) and in some occasions, its AI, PI, and size are smaller than the SOA (e.g., its AI is smaller than in [17], [26], [66], [67], [75], and [76], its PI is smaller than in [67] and [75], and its size is smaller than in [17], [26], [36], [65], [67], [70], [75], and [78]) while excluding [17], [26], it exhibits the widest FBW, which is very close to the optimally predicted 99% by the theoretical analysis in Section II-A. Although its loss may appear to be higher than certain integration concepts (e.g., LTCC [66], [75], [77], CMOS [67]), to the best of the authors' knowledge, this is the first time that a wideband MB has been implemented monolithically using a two-material inkjet printing process, which demonstrates comparable or even better performance (in terms of FBW) than SOA multilayer processes. Processes that are potentially more expensive require expensive cleanroom manufacturing facilities and do not facilitate such levels of design flexibility.…”