Fig. 1. Model of half circular ring helix slow wave structure and half rectangular ring helix slow-wave structure

Fig. 2. Effect of helix thickness on high-frequency characteristics with parameters of (in mm) b/a＝2, a＝0.10, w＝0.06, p＝0.20, c＝1.00, d＝1.00

Fig. 3. Effect of helix width w on high-frequency characteristics with parameters of (in mm) b/a＝2, a＝0.10, t＝0.01, p＝0.20, c＝1.00, d＝1.00

Fig. 4. Effect of the height b on high-frequency characteristics with parameters of (in mm) a＝0.10, t＝0.03, w＝0.06, p＝0.20, c＝1.00, d＝1.00

Fig. 5. Effect of the axial period on high-frequency characteristics with parameters of (in mm) a＝0.10, b/a＝2, t＝0.01, w＝0.06, c＝1.00, d＝1.00

Fig. 6. Effect of aspect ratio on high-frequency characteristics with parameters of (in mm) 4a＋4b＝1.22, t＝0.03, w＝0.06, p＝0.20, c＝1.00, d＝1.00

Fig. 7. Comparison of high frequency characteristics between the half circular ring helix slow wave structure and the half rectangular ring helix slow wave structure

Fig. 8. S parameters of half rectangular ring helix slow-wave structure