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Design Example: A 12 element Yagi-Uda Array. Q. Design a 12-element Yagi at 205.25 MHz using 1 cm diameter elements. Step 1: Find the driven element length. Follow the steps done in Project 1 to come up with the optimum length . Start with L=0.5 l
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Design Example: A 12 element Yagi-Uda Array • Q. Design a 12-element Yagi at 205.25 MHz using 1 cm diameter elements. • Step 1: • Find the driven element length. Follow the steps done in Project 1 to come up with the optimum length. Start with L=0.5l • Then use Table 5.4 and curves provided in the notes to find lengths of reflector and directors. From the table, for 12 element Yagi, the required boom length is 2.2l and SR=SD=0.2l • Step 2:Find the diameter in l. 1cm0.0065l.
3. Find LR by drawing a vertical line at 0.0065l that intersects reflector curve B LR=0.483l
4. Find LD1 corresponding to d=0.0085l and 0.0065l and mark them on director curve B Find the distance between the two points on curve B with the help of a divider. This correction will be added to all director lengths. LD1=0.4375 LD1=0.4375
5. Mark the length LD2 from the table on curve B. Add the correction and find new length. Repeat for all the directors. LR=0.483l LD1=0.4375 LD2=0.421 LD3=0.414=LD10
5. Mark the length LD2 from the table on curve B. Add the correction and find new length. Repeat for all the directors. LR=0.483l LD1=0.4375 LD2=0.421 LD3=0.414=LD10
Design Example: A 12 element Yagi-Uda Array • Summary of the design • L=0.4781l=0.6988m. • LR=0.483l=0.483x1.4616=0.706 m • LD1=0.4375l=0.639 m • LD2=0.421l=0.6153 m • LD3=LD10=0.414l=0.6051 m • LD4=LD9=0.405l=0.5919 m • LD5=LD6=LD7=LD8=0.398l=0.5817 m • SD=SR=0.2l=0.2923 m
E-Plane H-Plane 12 element Yagi 3 element Yagi Half-Wave Dipole