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.
  6. 6. Radiation pattern
  7. 7. Cylindrical 3 strip antenna
  8. 8. Hfss module
  9. 9. Resoanace frequency 2.77GHz return loss -17db
  10. 10. Radition pattern
  11. 11. Cylindrical 2 strip antenna
  12. 12. Resoanace frequecy vs s11resonace frequency=3.41GHz and return loss=-17db
  13. 13. Radiation pattern
  14. 14. Cylindrical single strip
  15. 15. Frequency vs return loss
  16. 16. Bifolded monopole antenna for naval commnication H=24cm,W=4cm,w=1.6cm,h=12cm C L H L C h L CUPPER L,C LOADING L=3MICRO H ANDC=3NF LMIDDLE L,CLOADING L=2MICROH AND C=2.2NF,LOWER L,C L=3MICRO H ANDC=2.5NF GROUND PLANESI=3000X3000 MM
  17. 17. Hfss design
  18. 18. Vswr<3 from 4mhz to 30mhz
  19. 19. Impedance of antenna
  20. 20. References…….. 1-Antenna theory analysis and design third edition “constantine A.balanis page 27 to 102.and page 497 to 521 and page 557 to 575. 2-cylindrical antennas and arrays and enlarged 2nd edition of array of cylindrical dipole Ronald ,W.P.king George J fikioris,rechard B.Mach. 3-IEEE transation on antennas and propagation, vol41 no.2 febuary1993 Cylindrical rectangular microstrip patch antenna for circular polarization”keh lu wong shyh-yeong ke” 4- A curved spiral antenna above a conducting cylinder (Hisamatsu Nakano, Fellow IEEE,and Kazuo Nakayama, Member IEEE) IEEE Transactions on antenna and propagation , vol,47,no.1,january1999. 5-IEEE Transation antennas and propagation vol.56.no.3 march 2008. Metamaterial-inspired efficient electrically small antenna.”Aycan Erntok.member ,IEEE,and Richard W.Ziolkowski,fellow ,IEEE. 6-IEEE antenna and wireless propagation letters,vol 4,2005. 7-Design of a broad band HF antenna for multimode naval communication Lorenzo Mattioni and Gaetano Morrocco, Member, IEEE.