Intermodulation suppression in a broad band TWT

We examine methods for reducing two-tone intermodulation products in the custom-made XWING broadband traveling wave tube. Harmonic suppression, and difference frequency techniques are used to demonstrate intermodulation suppression and the spatial variation of their spectral evolution. Harmonic and difference frequency optimum drive levels and phase are determined which suppress the third-order intermodulation product by more than 21 dB in the 2-6 GHz band. The variation of the suppression with drive level near saturation and two-tone difference frequency are examined. IM3 reduction using the harmonic injection technique is experimentally demonstrated in a broadband TWT distributed amplifier.