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# Helical antenna

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### Helical antenna

1. 1. Helical antenna by subhash yadav under guidance of prof..Bratin ghosh
2. 2.  antenna diamentions Monopole hight=595mm.copper Monopole radius=1mm. Helix pitch length =20mm. Helix radius=50mm. Nomber of turns=25. Rect hight=15mm. Rect metal thickness=10mm copper Ground plane =5000X5000 mm. Total helix hight=25(15+20)=875mm Coaxial feed is given inside the ground outer radius of condutor is shown in figure and inner radius is radius of monopole antenna.
3. 3. Basic priciple Helix antenna is exited by electric field generated by monopole in near field. Flux is captured by helix antenna and change of flux with time produced induce current in helix this induce current produces inductance in the system. Strong electric field genrated by monopole antenna in near field create capacitance in the syastem. The conductor loss is due to monopole antenna radius and thickness of metal strip. So RLC system form in whole system . Monopole antenna and helix are properly adjusted for tuning if helix pitch length is small and rectangle length is large it produce large inductance because higher metal density.
4. 4.  Hight of monopole antenna dermine resoanace behavior of antenna higher monopole length create strong resoanace and small monopole create low resonance . This antenna can be scale defferent frequency range for proper adjustment of monopole hight and helix paramer. This antenna is design for naval communication in the frequncy of 18.6 MHz. This antenna shifted lower frequency by increasing pitch of helix because metal density between two turns are reduce.
5. 5. Ansoft hfss simulated results Resoance frequency=18.6MHz and corresponding S 11=-9.5db.as shown in frequency vs S11 graph.
7. 7. Cylindrical 3 strip antenna
8. 8. Hfss module
9. 9. Resoanace frequency 2.77GHz return loss -17db