Wideband uniplanar 180° phase switch

A wideband 180deg phase switch is developed at millimetre-wave frequencies (31 GHz centre frequency) using uniplanar technology. The circuit is designed using coplanar-to-slotline transitions and commercial pin diodes as switching devices. The implementation is straightforward, fast in terms of fabrication and low-cost. The circuits tested, made on an alumina substrate, show a phase difference between states of 180deg plusmn 2deg, providing 40% bandwidth with in-band insertion loss lower than 2.5 dB and a return loss better than 10 dB. The phase switch provides a plusmn5deg phase error in a bandwidth of around 60%, from 18 to 38 GHz.