Modified Hairpin Unit with High Slow-wave Characteristics and Application to Miniaturization of Power Divider

This paper presented a compact Wilkinson power divider (WPD) operating at 0.9GHz with harmonic suppression based on the compact modified hairpin unit (MHPU). First, HPU is designed with low impedance (coupled line) and high impedance section. Further, the structure is modified by folding the low impedance section inside the free space of HPU and analyzed its slow-wave characteristics. The proposed unit provides high slow-wave characteristics compared to the reference line. In addition to this, two transmission zeros (TZs) are obtained by adjusting the impedances and electrical lengths of HPU. The proposed unit is used to design a compact WPD due to the high slow-wave factor (SWF). Therefore, the physical dimension of the proposed WPD occupied only 76% circuit area compared to reference WPD. In addition to this, two transmission zeros are also observed in the frequency response above the operating band, which are properly tuned to suppress 2nd and 3rd order harmonics by more than 40dB.