Compact design of wide-band balun for dual-linear polarization microstrip antenna array

A wideband compact balun for P-band dual-line polarization antenna system applications is provided, where the center frequency is 400 MHz with a 200 MHz of bandwidth (50% from 300 MHz to 500 MHz), and the size is smaller than 400 mm × 42 mm. It is important to feed by balance balun to realize perfect cross-polarization level of antenna array. One of the most excellent achievements is to develop an integrated and compact feed-line distribution to obtain low insertion loss.