1. Helical antenna
by
subhash yadav
under guidance of
prof..Bratin ghosh

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. 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.  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. Ansoft hfss simulated results
 Resoance frequency=18.6MHz and corresponding
 S 11=-9.5db.as shown in frequency vs S11 graph.

6. Radiation pattern

9. Cylindrical 3 strip antenna

10. Hfss module

11. Resoanace frequency 2.77GHz return loss -17db

12. Radition pattern

15. Cylindrical 2 strip antenna

16. Resoanace frequecy vs s11
resonace frequency=3.41GHz and return loss=-17db

17. Radiation pattern

20. Cylindrical single strip

21. Frequency vs return loss

22. Bifolded monopole antenna for naval commnication
H=24cm,W=4cm,w=1.6cm,h=12cm
C
L
H
L C
h
L C
UPPER L,C LOADING L=3MICRO H ANDC=3NF LMIDDLE L,C
LOADING L=2MICROH AND C=2.2NF,LOWER L,C L=3MICRO
H ANDC=2.5NF
GROUND PLANESI=3000X3000 MM

23. Hfss design

24. Vswr<3 from 4mhz to 30mhz

25. Impedance of antenna

26. 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.