design of a uhf pyramidal horn antenna using...

Design of a UHF Pyramidal Horn Antenna Using CST

Biswa Ranjan Barik and A.Kalirasu

Department of EEEM, AMET University , Chennai, India

[email protected] and [email protected]

Abstract

This technical paper highlights about design of pyramidal horn

antenna and simulation of its parameters using computer simulation

technology. Horn antennas are extensively used in the fields of T.V.

broadcasting, microwave devices and satellite communication. Since

horn antennas do not have any resonant elements they operate at

wide range of frequencies and have a wide bandwidth. They are also

used as high gain devices in phased arrays and as a feeder for

reflector and lens antennas in satellite communication. The material

used in the design of antenna is Perfect Electric Conductor (PEC).

The designed Pyramidal horn antenna is functional for each UHF-

band applications and here it is having gain of 5dB operating at

2.8GHz frequency. The performance parameters like Directivity,

impedance, Efficiency, s-parameters are evaluated using CST

Key Words:- Horn Antenna, resonant element, Phased arrays,

Feeder, PEC,CST

1. Introduction

The horn antenna is most widely used simplest form of microwave

antenna, which comes from the aperture antenna family. The first horn

antenna was constructed by an Indian radio researcher and one of the father

of radio science Jagadish Chandra Bose (1858-1937), in the year 1897. The

horn makes a transition of EM waves propagating in a waveguide, and

launches it into free space. The flaring of the metal helps in the gradual

International Journal of Pure and Applied MathematicsVolume 114 No. 7 2017, 447-457ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

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matching of the impedance of the waveguide, usually 50 Ω, to that of the

free space i.e., 377 Ω. The advantages of a horn are its wide bandwidth, low

VSWR and simplicity of construction and adjustment. They are designed in

variety of shapes and sizes to fulfill many practical applications, such as

communication systems, electromagnetic sensing, directive antenna

applications, microwave applications, biomedical applications and as a

reference source for testing of other antennas. These horns can be used as

feeds for other antennas such as reflectors, compound and lens antennas.

Due to such a vast area of application and advantages, the horn antenna can

be preferred over other aperture antennas. Basically the horn antennas are

classified as rectangular horn antennas and circular horn antennas. The

rectangular horns are further divided into sectoral horn and pyramidal horn.

The sectoral horn is divided into two types based on the direction of flaring

in accordance of the field vectors. The E – plane sectoral horn is obtained

when the flaring is done in the direction of the electric field vector . The H

– plane sectoral horn is obtained when the flaring is done in the direction of

the magnetic field vector. When the flaring of the walls of the waveguide is

done along the direction of both E and H field vectors, it gives rise to a horn

called Pyramidal Horn The pyramidal horn antennas are the most

extensively used antennas since they have the combined characteristics of

both E – plane and H – plane sectoral horns.

2. Antenna Parameters

The characteristics of an antenna can be understood by the antenna

parameters. The various parameters such as radiation pattern, beam width,

directivity, radiation intensity help us for the analysis of an antenna.

2.1 Antenna Radiation Pattern

It is the graphical representation of electric and magnetic fields at all points

equi-distance from the antenna. It gives radiation properties of an antenna

as a function of space coordinates. If it is measured in terms of volts/m then

it is called “Field Radiation Pattern”. If it is measured in terms of power per

unit solid angle, then it is called “Power Radiation Pattern”. The relative

measure of magnitude of the antenna’s ability to direct or concentrate the

electromagnetic energy in a particular direction or pattern is called “Gain”.

It is measured in decibels. The expression to calculate the Gain is

max( , )

...........(1)( , )average

PD

P

The Directivity of an antenna is its capability to direct or concentrate the

radiated power in a particular direction and attenuate in undesirable

directions.

International Journal of Pure and Applied Mathematics Special Issue

448

4

4 4...................(2)

( , ) An

DP d

Radiation intensity is the measure of the power radiated from an antenna per unit

solid angle in a given direction. It is a far-field parameter. Total power radiated is

given by

2

0 0

sin .............(3)radP Ud U d d

3. Design Equations of Horn Antenna

The electromagnetic horn produces uniform phase front with larger aperture

as compared to wavelength. Because the horn aperture, at higher

frequencies, is electrically larger when compared to wavelength. Due to

this the directivity increases. Assuming that there is a line source which

radiates cylindrical waves, and the dimensions of the imaginary apex of

the horn as shown in the figure. Where, δ is the difference in the path of

travel, θ is the flare angle, h is the height of aperture, ρ is length of aperture.

Fig:1 Section view of Horn Antenna

Then from geometry[4]


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.....................................(4)COS

Also

2tan ..................................(5)

2

hh

Hence we get

1 1tan .................(6)

2

hCOS

The angle θ represented in equation is called the optimum aperture angle.

The directivity of maximum value can be obtained at the largest flare angle

for which the path difference does not exceed typical values of 0.32 λ for

conical horn, 0.25 λ for plane horn and 0.40 λ for H – plane sectoral horn

antenna. Because of more than one flare angle the pyramidal and conical

horn antenna has the highest directivity compared to any other horns.

For optimum flare horn, the half power beam width can be approximated as

67

......................(7)H

Ha

And

56........................(8)E

Ea

Directivity in terms of effective aperture of the horn as

2 2

44...................(9)

ap peAA

D

Where Ae is effective aperture, in m2,

Ap is physical aperture, in m2 ,εap = Ae /Ap is Aperture efficiency


450

4. Pyramidal Horn Antenna using CST

The pyramidal antenna is generally excited using a waveguide which is fed

with a coaxial cable. The antenna here is constructed using a simulation

software called Computer Simulation Technology (CST) and it is assumed

that antenna is made up of PEC; the plates of finite thickness are modeled

as infinitesimally thin plates resulting in surface currents that represent the

sum of interior and exterior antenna currents. This software has the

maximum of 30,000 cells.The geometry of a horn antenna with spatial

coordinates is as xmin = -25; xmax = 25 and ymin = -14; ymax = 14 and zmin = 0

and zmax = 70 modeled as shown in Figure. Pyramidal flare of horn antenna

is the most significant part in the antenna design, which varies the

impedance of waveguide from 50Ω at the feeding point to 377Ω at the

aperture of the antenna. The symmetry feature in both electric and magnetic

planes can be used, so as only half or quarter of given antenna can be

modeled. The gain obtained is 5.50 dB approximately, near field is

observed and analysis characteristics for different models of antenna at

various frequencies are observed.

Fig. 2 Pyramidal Horn Antenna using CST

5. Simulation and Experimental Results


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Fig. 3. S- Parameter

Fig. 4 VSWR

Fig. 5. Power Excitation Signals

Fig. 6. Input Excitation Signal


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Fig. 7. 3D Plot of gain for 3GHz

Fig. 8. Polar Plot of gain for 3GHz

Fig. 9. Polar Plot of gain for 6GHz

Fig. 10. 3D Plot of gain for 6GHz


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Figure-1 Shows the analysis of the design with S(1,1) parameters. S-

parameters are called complex scattering parameters because both the

magnitude and phase of the input signal are altered by the network. Due to

impedance mismatch some energy is reflected back in the system which is

called as return loss (dB). It is a numerical measure of dissimilarity between

impedances of loads and metallic transmission lines. It is important in

applications that use simultaneous bidirectional transmission. Larger values

of it indicate less reflection. The value of -15 to-20 dB and higher are

considered acceptable.

Figure-2 shows VSWR graph. Voltage standing wave ratio gives the

value that how our antenna is matched with transmission line impedance or

with load resistance. The simulated value for voltage standing wave ratio is

less than 2 and hence can be fair for signal transmission when low

attenuation is present. It also concludes that the designed antenna is

matched to the operating frequency. Both VSWR and Return loss play an

important role in the study of transmission from antenna and reception of

signal.

Figure-3 shows the power excitation of the designed antenna. The

amount of power accepted, radiated, Power outgoing of all port and power

stimulated

Figure-4 shows the default excitation signal which is used to activate the

antenna.

Figure-5 shows the 3D and polar plot of gain which shows the magnitude

of main lobe for the designed Pyramidal horn antenna. The value is found

to be 5.49 dBi.

6. Conclusion

The successful implementation and simulation of pyramidal horn antenna is

done by using CST. As a result of experimental studies, it is evident that

signal integrity be intercepted or transmitted depend on the design

considerations of the pyramidal horn antenna. These antennas can be

enhanced using dielectric lens, good conductive materials and ridges. They

are used significantly where directivity of signal is of main concern. CST is

a useful tool for better 2D and 3D analysis and design of antenna structure

within small time. By using CST simulation results, we have designed our

antenna of gain 5dB with a resonant frequency of 2.8GHz, VSWR is 2 and

normalized impedance of 50Ώ.

References


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[1] Ayodele S.Oluwole,viranjan M.Srivastava, “Design of smart antenna using waveguide-fed pyramidal horn antenna for wireless communication systems”, IEEE(INDCON),2015. [2]. N.Smitha,Vipula Singh,S.N.Sridhara, “Pyramidal horn antenna for ground penetrating radar application”, IEEE(INDICON), 2016. [3] Katsushige Harima, Makato Sakasai, Katsumi Fujji, “Determination of gain for pyramidal horn antenna on basis of phase center location”, IEEE (ISEC), 2008. [4]. Deqinsyang, Sihaolio, Bao Sun, Jin Pan, “Research on Pyramidal Horn Antenna using integrating optical E – field probe”, IEEE (APMC), Vol.3, 2015. [5] Chintin A. Patel, Shobhit K. Patel, “Pyramidal Horn antenna design loaded by meta – material for performance enhancement”, IEEE (MEMO), 2015. [6]. Aniket Bhumkar, “Design and Implementation of Pyramidal Horn Antenna,” IJRASET, Vol. 3 Issue V, May 2015. [7] Arvind Roy, “Design and Analysis of X band Pyramidal Horn Antenna Using HFSS,” IJARECE, Vol. 4 Issue 3, March 2015. [8] Daniyan O.L., “Horn Antenna Design: The Concepts and Considerations,” IJETAE, Vol. 4 Issue 5, May 2014. [9]Priyanka Bhagwat, “High gain Conical Horn Antenna for short range communications”, IJERA, Vol 3 Issue 6, Nov-Dec 2013. [10]. Arvind Roy, Isha Puri, “Design and Analysis of X band Pyramidal Horn Antenna Using HFSS”, IJARECE, Volume 4, Issue 3, March 2015. [11]. G.Abhignya, B.Yogita, C.Abhinay, B.Balaji, MBR Murthy, “Design, fabrication and testing of pyramidal horn antenna”, IJEAS ISSN: 2394-3661, Volume-2, Issue-4, April 2015


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