The　electric　performance　of　static　induction　transistor　(SIT)　is　dependent　strongly　on　the　channel　parameters　of　device.　The　ratio　of　is　an　essential　combined　channel　parameter　not　only　for　I-V　characteristics　but　also　for　the　high-current　performance　of　device　especially　for　the　high　frequency　SIT　(HF　SIT),　which　are　researched　in　this　article.　The　pinch　factor　is　also　a　key　combined　channel　parameter　embodies　the　general　control　criterion　of　fabrication　parameters　in　determining　whether　it　is　a　mixed,　triode-like　or　pentode-like　I-V　characteristic　which　are　also　studied　in　detail.　A　great　deal　of　experimental　results　is　given　which　are　available　and　convenient　for　design　and　fabrication　of　HF　SIT,　particularly　for　mixed　I-V　non-saturating　characteristics.　©　2011　Springer-Verlag　Berlin　Heidelberg.