Offset quad ridged ortho-mode transducer with a 3.4:1 bandwidth

We describe the design and measured parameters of an offset probe, quad ridged, ortho-mode transducer (OMT). The OMT operates over a 3.4:1 bandwidth from 3.6-12.4GHz. The OMT exhibits a return loss of greater than 15dB and an isolation of greater than 50dB across the full band. Simulations predict spurious mode production at the circular waveguide port to be greater than 15dB below the TE11 mode.