Design Simulation and Performance Analysis of Strip-Line Feed Rectangular Micro-Strip Patch Antenna

Full text

(1)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, UGC Approved List of Recommended Journal, Volume 8,Issue 3, March 2018)

222

Design Simulation and Performance Analysis of Strip-Line

Feed Rectangular Micro-Strip Patch Antenna

T. Nagarjuna¹, K.Shivaramakrishna², U.Rajini

3

, G.Meena

4

, K.Ratnaprasad

5

, B.Ashok

6 1Assistant Professor, Department of ECE, CMR Technical Campus, JNTU Hyderabad 2-6Engineering Project Students²˒³,Department of ECE,CMR Technical Campus, JNTU Hyderabad

Abstract :-There Are Various Types Of Microstrip Antenna That Can Be Used For Many Applications In Communication Systems. This Paper Presents The Design Of A Rectangular Microstrip Patch Antenna To Operate At Frequency Range Of 3ghz. This Antenna, Based On A Thickness Of 1.6mm Fire Retardant 4 (FR-4) Substrate With A Dielectric Constant Of Approximately 4.4, Is A Strip Line Feed And Has A Partial Ground Plane. After Simulation, The Antenna Performance Characteristics Such As Return Loss, VSWR ,GainAnd Current Density Are Obtained.

Keywords:–Rectangular Microstrip Antenna, Strip Line Feeding, HFSS, Fire Retardant 4 (FR-4).

I. INTRODUCTION

Antennas play a very important role in the field of wireless communications. Some of them are parabolic reflectors, patch antennas, slot antennas, and folded

dipole antennas with each type having their own properties and usage. It is perfect to classify antennas as the backbone and the driving force behind the recent advances in wireless communication technology.

Because of the great demand in wireless communication system and UHF applications, microstrip patch antennas have attracted much interest due to their low profile, light weight, ease of fabrication and compatibility with printed circuits. Microstrip patch antenna in its simplest form consists of a radiating patch (of different shapes) which is made up of a conducting material like Copper or Gold on one side of a dielectric substrate and a ground plane on the other side. It is used in communication systems due to simplicity in structure, conformability, low manufacturing cost, and very versatile in terms of resonant frequency, polarization,

pattern and impedance at the particular patch shape model[1]

Microstrip antennas are characterized by a largernumber of physical parameters than conventional microwave antennas. They can be designed to have many geometrical shapes and dimensions but rectangular and circular Microstripresonant patches have been used extensively in many applications[2]. In this paper, the design of strip line feed rectangular microstrip patch antenna is for wireless applications is presented and is expected upto 3GHz frequency span.Its performance characteristics which include Return Loss, VSWR, Gain and current density are obtained from the simulation.

(2)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, UGC Approved List of Recommended Journal, Volume 8,Issue 3, March 2018)

223

II

. A

NTENNA

G

EOMETRY

There are some standard formulae which have to be followed to calculate the length, width, height of the elements used in the antenna design. They are as follows

eff = ⁄ (effective dielectric constant)

Leff = √

(effective length of patch)

( ) ( ) ( )( ) (extended length of patch)

L = Leff - 2 (actual length)

W = √ (Width of the patch)

Lg = 6h + L

(Length of ground and substrate)

Wg = 6h + W

(Width of ground and substrate)

Where

h = height of the substrate (1.6mm) f0=operating freq (3Ghz)

r = dielectric constant (4.4) C = speed of light (3* )

Fig 2: Proposed Rectangular Microstrip Patch Antenna

III.

D

ESIGN

R

EQUIREMENT

There are three essential parameters for design of astrip line feed rectangular microstrip Patch Antenna. Firstly, the resonant frequency ( f0 ) of the antenna must be selected appropriately. The frequency used is 3GHz and the design antenna must be able to operate within this frequency range. The resonant frequency selected for this design is 3GHz.

Secondly, the dielectric material of the substrate ( εr )selected for this design is FR-4 Epoxy which has a dielectric constant of 4.4.The dielectric constant of the substrate material is an important design parameter. Low dielectric constant is used in the prototype design because it gives better efficiency and higher bandwidth, and lower quality factor Q. The lowvalue of dielectric constant increases the fringing field at the patch periphery and thus increases the radiated power.The proposed design has patch size independent of dielectric constant. So the way of reduction of patch sizeisby using higher dielectric constant and FR-4 Epoxy is goodin this regard. The small loss tangent was neglected in the simulation.

Lastly, substrate thickness is another important designparameter. Thick substrate increases the fringing field at the patch periphery like low dielectric constant and thus increases the radiated power. The height of dielectric substrate (h) of the microstrip patch antenna with stripline feed is to be used in C-band range frequencies. Hence, the height of dielectric substrate employed in this design of antenna is h=1.6 mm.

IV.

S

IMULATION

&

R

ESULTS

Fig 3:Graph of Return loss

In telecommunications, return loss is the loss of power in the signal returned/reflected by a discontinuity in a transmissionline or opticalfibre. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line. It is usually expressed as a ratio in decibels (dB);

(3)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, UGC Approved List of Recommended Journal, Volume 8,Issue 3, March 2018)

224

where RL(dB) is the return loss in dB, Pi is the

incident power and Pr is the reflected power.

Return loss is related to both standingwaveratio (SWR)

and reflectioncoefficient (Γ). Increasing return loss corresponds to lower SWR. Return loss is a measure of how well devices or lines are matched. A match is good if the return loss is high. A high return loss is desirable and results in a lower insertionloss.Return loss is used in modern practice in preference to SWR because it has better resolution for small values of reflected wave.[4]

Fig 4 :Graph of VSWR

VSWR (Voltage Standing Wave Ratio), is a measure of how efficiently radio-frequency power is transmitted from a power source, through a transmission line, into a load (for example, from a power amplifier through a transmission line, to an antenna).

In an ideal system, 100% of the energy is transmitted. This requires an exact match between the source impedance, the characteristic impedance of the transmission line and all its connectors, and the load's impedance. The signal's AC voltage will be the same from end to end since it runs through without interference.

In real systems, mismatched impedances cause some of the power to be reflected back toward the source (like an echo). Reflections cause destructive interference, leading to peaks and valleys in the voltage at various times and distances along the line.

VSWR measures these voltage variances. It is the ratio of the highest voltage anywhere along the transmission line to the lowest. Since the voltage doesn't vary in an ideal system, its VSWR is 1.0 (or, as commonly expressed, 1:1). When reflections occur, the voltages vary and VSWR is higher -- 1.2 (or 1.2:1), for instance.

Mathematically:

VSWR is the voltage ratio of the signal on the transmission line:

VSWR = |V(max)| / |V(min)|

where V(max) is the maximum voltage of the signal along the line, and V(min) is the minimum voltage along the line.

It can also be derived from the impedances: VSWR = (1+ )/(1- )

where (gamma) is the voltage reflection coefficient near the load, derived from the load impedance (ZL) and the source impedance (Zo):

= (ZL-Zo)/(ZL+Zo)

If the load and transmission line are matched, = 0, and VSWR = 1.0 (or 1:1)

Fig 5 :3D Radiation Pattern

In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the directional (angular) dependence of the strength of the radio waves from the antenna or other source.[6][7][8]

Particularly in the fields of fiber optics, lasers, and integrated optics, the term radiation pattern may also be used as a synonym for the Near-field pattern or Fresnel pattern.[9]This refers to the positional dependence of the electromagnetic field in the field, or Fresnel region of the source. The near-field pattern is most commonly defined over a plane placed in front of the source, or over a cylindrical or spherical surface enclosing it.[6][9]

Fig 6 :2D Radiation Pattern 1

(4)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, UGC Approved List of Recommended Journal, Volume 8,Issue 3, March 2018)

225

Fig 8 :Current Distribution

The current distribution plot gives the relationshipbetween the co-polarization (desired) and cross-polarization(undesired) components. Moreover, it gives a clear picture as to the nature of polarization of the fields propagating through the patch antenna. The average current density is shown clearly in figure 8 as different colors on the surface of the antenna which implies that the patch antenna is linearly polarized.

Fig 9 :Smith Chart

The Smith chart is plotted on the complexreflection coefficient plane in two dimensions and is scaled in normalised impedance (the most common), normalised admittance or both, using different colours to distinguish between them. These are often known as the Z, Y and YZ Smith charts respectively.[11] Normalised scaling allows the Smith chart to be used for problems involving any characteristic or system impedance which is represented by the center point of the chart. The most commonly used normalization impedance is 50 ohms. Once an answer is obtained through the graphical constructions described below, it is straightforward to convert between normalised impedance (or normalised admittance) and the corresponding unnormalized value by multiplying by the characteristic impedance (admittance). Reflection coefficients can be read directly from the chart as they are unitless parameters.

Fig 10: 3D Polar Plot

Typical polar radiation plot.Most antennas show a pattern of "lobes" or maxima of radiation. In a directive antenna, shown here, the largest lobe, in the desired direction of propagation, is called the "main lobe". The other lobes are called "sidelobes" and usually represent radiation in unwanted directions.

Fig 11 :(Gain)3D Polar Plot

In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an anglefrom a reference direction.

The reference point (analogous to the origin of a Cartesian coordinate system) is called the pole, and the ray from the pole in the reference direction is the polar axis. The distance from the pole is called the radial coordinate or radius, and the angle is called the angular coordinate, polar angle, or azimuth.[10]

V.

C

ONCLUSION

The research motivation of this project is to design

(5)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, UGC Approved List of Recommended Journal, Volume 8,Issue 3, March 2018)

226

VI.

A

CKNOWLEDGEMENT

We would like to express our deepest appreciation to all those who provided us the possibility to complete this report. A special gratitude we will give to our final year project Guide, Mr.T.Nagarjuna (Assistant Professor) whose contribution in stimulating suggestions and encouragement, helped us to coordinate our project especially in writing this report

.

REFERENCES

[1].M. Jo. C. G. Lim. and E. W. Zimmers, "RFID tags detection on water content using a background-propagation" KSII Trans. On Internet and Information Systems, vol. 1, no. 1,pp. 19-32,2207.

[2] Ramesh G, Prakash B, Inder B, and Ittipiboon A. (2001) Microstrip antenna design handbook, Artech House.

[3]Balanis C.A. (2005) Antenna Theory: Analysis and Design, John Wiley & Sons

[4].Trevor S. Bird, "Definition and Misuse of Return Loss", IEEE Antennas & Propagation Magazine, vol.51, iss.2, pp.166-167, April 2009

[5]https://www.maximintegrated.com/en/glossary/definitions.mvp/term/ VSWR/gpk/815

[6] Constantine A. Balanis: “Antenna Theory, Analysis and Design”, John Wiley & Sons, Inc., 2nd ed. 1982 ISBN 0-471-59268-4

[7] David K Cheng: “Field and Wave Electromagnetics”, Addison-Wesley Publishing Company Inc., Edition 2, 1998. ISBN 0-201-52820-7

[8] Edward C. Jordan & Keith G. Balmain; “Electromagnetic Waves and Radiating Systems” (2nd ed. 1968) Prentice-Hall. ISBN 81-203-0054-8

[9] Institute of Electrical and Electronics Engineers , “The IEEE standard dictionary of electrical and electronics terms”; 6th ed. New York, N.Y., Institute of Electrical and Electronics Engineers, c1997. IEEE Std 100-1996. ISBN 1-55937-833-6 [ed. Standards Coordinating Committee 10, Terms and Definitions; Jane Radatz, (chair)]

[10] Brown, Richard G. (1997). Andrew M. Gleason, ed. Advanced Mathematics: Precalculus with Discrete Mathematics and Data Analysis. Evanston, Illinois: McDougal Littell. ISBN 0-395-77114-5.

Figure

Fig 1: Rectangular Microstrip Patch Antenna

Fig 1:

Rectangular Microstrip Patch Antenna p.1
Fig 3:Graph of Return loss

Fig 3:Graph

of Return loss p.2
Fig 2: Proposed Rectangular Microstrip Patch Antenna

Fig 2:

Proposed Rectangular Microstrip Patch Antenna p.2
Fig 6 :2D Radiation Pattern 1

Fig 6 :

2D Radiation Pattern 1 p.3
Fig 5 :3D Radiation Pattern

Fig 5 :

3D Radiation Pattern p.3
Fig 4 :Graph of VSWR

Fig 4 :

Graph of VSWR p.3
Fig 7 :2D Radiation Pattern 2

Fig 7 :

2D Radiation Pattern 2 p.3
Fig 8 :Current Distribution

Fig 8 :

Current Distribution p.4
Fig 10: 3D Polar Plot

Fig 10:

3D Polar Plot p.4
Fig 9 :Smith Chart

Fig 9 :

Smith Chart p.4

References

Updating...