A low impedance and short-guided wavelength microstrip line antenna employing a PPGM and its application to highly miniaturized passive components on GaAs MMIC

In this work, in order to realize highly miniaturized and low impedance rat race on GaAs MMIC, novel microstrip line structure employing PPGM (periodically perforated ground metal) was proposed. The novel microstrip line structure exhibited much lower characteristic impedance and shorter guided-wavelength than conventional one. Using the novel microstrip line, a highly miniaturized rat race with a low port impedance of 10.6 Ω was developed for K/Ka band MMIC applications. It was fabricated on GaAs substrate with a height of 100 μm, and its size was 0.375 mm², which was 9.3% of the one fabricated by conventional microstrip line. The rat race exhibited good RF performances from 20 to 30 GHz. In addition, in this work, a fully integrated power amplifier MMIC, which includes miniaturized power divider and combiner, was also fabricated by using the novel microstrip line structure. It showed good RF performances in K-Ka band.