Metamaterial-based backward wave oscillators (BWOs) represent a significant advancement in the generation of coherent microwave radiation. These devices exploit engineered metamaterials—materials ...

A long thin glass tube with a metal cap on the bottom and six pins, a contact and an exhaust tip on top. Donor’s card reads: “Backward wave oscillator made by Stewart Engineering Company, Santa Cruz, ...

A long thin glass tube with a metal cap on the bottom and six pins and an exhaust tip on top, one pin in the side. Donor’s card reads: “Backward wave oscillator made by Stewart Engineering Company, ...