LAUSR

A broadband microstrip-to-waveguide end-wall probe transition using a semicircular loop is proposed in this letter. The simulated 20-dB fractional bandwidth for this transition is 48.3% which could cover the whole Ka-band. Then, a compact broadband waveguide termination is developed by combination of this microstrip-to-waveguide transition and a 50 Ω microstrip termination. To reduce parasitic effects, the microstrip termination is grounded by a microstrip radial stub. The fabricated waveguide termination shows a compact size and has a return loss better than 16.6 dB from 26 to 40.8 GHz.