Antenna Calculations Final

7/30/2019 Antenna Calculations Final

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Project ProposalHere is the project proposal of the semester project that

you have asked us to prepare. The proposal provides all therequired information of our semester project that is Helical

Antenna, for the completion of Antenna and Wave Propagationcourse 6th semester. This proposal provides you with the basicinformation about our project.A helix is a fundamental form of antenna with many radiationmodes. A recently reported mode, called an axial or beammode, occurs for a relatively wide range of helix dimensions, inthe region of 0.2 to 0.5 wavelengths diameter and as high as0.5 wavelengths spacing between turns. The radiation ismaximum in the direction of the helix axis and is nearly

circularly polarized. This mode may persist with a given helixover a considerable frequency range. In this range the phasevelocity of wave propagation along the helical conductor isreduced. An approximate expression for the field pattern of asingle turn helix is developed. The pattern of a helix of anumber of turns is then calculated as an array of such turns.Measured and calculated patterns show good agreement.

Helical AntennaWe will be making a helical antenna for which first

calculations are needed which is detailed at the end section.We will be using software HFSS for the design and modeling ofthe Antenna.Here are some pictures of helical antenna which we will bemaking.


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Radiation Patern:


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Salient Features:

1) Helical antennas are mounted over a ground plane.


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2) Helical antennas can operate in one of two principal

modes: normal mode or axial mode.

3) These can be easily constructed.

4) These antennas are circularly polarized.

5) These have real input impedance.6) The radiation pattern will be maximum in the +z direction.

Method to Increase Gain:

To increase gain we have to simply increase number of turn of winding of

helical antenna.In this we get more gain in terms of dBi.

Antenna Calculations

Various parameters for designing of antenna

Lambda (wavelength) = 0.0300m

f (frequency) = 10000 MHz(MHz)

N (Number of Turns ) = 10

S (Spacing between coils) =0.25 (wavelengths)

G (Antenna Gain) = 14.8 (dBi)

Z (Characteristic Impedance) =150 (Ohms)

D (Diameter) =0.955 (cm)

S (Spacing between coils) =0.750 (cm)

L (Length of wire) =252 (cm)

HPBW (Half Power BW) =32.9 (degrees)

BWFN (BW first nulls) =72.7(degrees)


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Ae (Effective Aperture) =0.00215 m2

Equations for finding antenna parameters

We have used following equations for finding the various parameters which are

required in designing antenna. These equations are as followed.

Equations:

G= 10.8 + 10*log10 ( (C/lambda)2*N*(S/lambda) )

Z= 150/sqrt(C/lambda) Ohm

D= lambda /PI

S= C/4

HPBW= 52/( (C/lambda)*sqrt(N*(S/lambda)) ), Half power beam width.

BWFN= 115/( (C/lambda)*sqrt(N*(S/lambda)) ), Beam width first nulls.

Ae= D*lambda2/(4*PI)

Where C is circumference, which is normally chose to be close to one

wavelength.

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Antenna Calculations Final