Wideband microstrip-to-waveguide transition using double-Y balun

A novel, broadband microstrip-to-waveguide transition for X-band is presented. It is highly reproducible and easy to assemble, as it requires no electrical contact with the waveguide walls. The transition realised with large loss tangent substrate demonstrates low insertion loss -0.35dB at the centre frequency as well as 31% bandwidth with return loss better than -12dB.