A Modified Sinusoidal SWS with Dominant TM01 Mode and Improved Interaction Impedance for Use in BWOs

A modified sinusoidal slow wave structure with a dominant TM
₀₁
mode which is the main interaction mode for a backward wave oscillator is proposed. The TM
₀₁
mode dominance is achieved by introducing circular discs along the circumferential ends of the conventional sinusoidal SWS. SWS designs for individual control of TM
₀₁
and TE
₁₁
mode cut-off frequencies are proposed. This SWS is also capable of coupling with a higher phase velocity as compared with the conventional sinusoidal SWS and exhibits improved interaction impedance characteristics which make them ideal candidates for use in backward wave oscillators.