VIETNAM NATIONAL UNIVERSITY, HANOI

UNIVERSITY OF ENGINEERING AND TECHNOLOGY

Duong Thanh TungNguyen Cong Tien

Tran Quang NhuongNguyen Minh Tran

ARRAY ANTENNA FOR S-BAND SATELLITE COMMUNICATIONS SYSTEMS

Research advisor: Assoc.Prof. Truong Vu Bang Giang

HA NOI - 2014

Abstract

A ground station is a terrestrial terminal station designed for extra planetary

telecommunication with spacecraft. Ground stations communicate with spacecraft by

transmitting and receiving radio waves in the super high frequency or extremely high

frequency bands, the use of large reflector antennas for space communication. Using

reflector antennas are expensive and require require the installation of a complex

mechanical system. Hence, with the development of antenna technology, one

alternative proposed is using array antenna.

Main advantages of antenna arrays over large reflectors are the higher

flexibility, less weight, lower production and maintenance cost, modularity and a more

efficient use of the spectrum. The proposed S-Band Patch antenna is being designed

and simulated using HFSS software. The designed patch array antenna meets almost

the parametric needs for a Polar orbiting satellite at Low Earth Orbit (LEO) region.

In our research project, an array antenna for S-band satellite communication

systems has been studied, designed, fabricated and measured. The results from the

designed antenna met all the above requirements.

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Table of Contents

Abstract.....................................................................................................................................................0

List of figure............................................................................................................................................3

1. Introduction....................................................................................................................................4

2. Design and Simulation of the Antenna................................................................................6

3. Results and Discussions.............................................................................................................9

4. Fabrication and Measurement.............................................................................................11

5. Conclusions...................................................................................................................................13

List of figure

Figure 1: Reference [5].......................................................................................................................4

Figure 2: Microstrip line feed..........................................................................................................6

Figure 3: Singer patch.........................................................................................................................7

Figure 4: Feeding network................................................................................................................7

Figure 5: 4 x4 array atenna...............................................................................................................8

Figure 6: Port and 3D model............................................................................................................8

Figure 7: Simulated return loss of the designed antenna...................................................9

Figure 8: 2D radiation pattern (phi = 0 deg)..........................................................................10

Figure 9: 2D radiation pattern (phi = 90 deg).......................................................................10

Figure 10: 3D radiation pattern...................................................................................................11

Figure 11: Fabricated antenna.....................................................................................................11

Figure 12: Connect the antenna to Network Analyzer......................................................12

Figure 13: Comparison between the simulation results...................................................12

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1. Introduction

Research objectives

A satellite like a moon, planet or machine that orbits something else like a

planet or star. Usually, the word "satellite" refers to a machine that is launched into

space and moves around Earth or another body in space [1]. Satellites can collect more

data, more quickly, than instruments on the ground. They are used mainly for

communications and other applications such as weather, military, television and radio

broadcast, and the Global Positioning System (GPS). The structure of satellite systems

most has at least two parts in common - an antenna and a power source.

Since the low cost and low weight specifications are of importance, micro-strip

antennas are mostly used. Microstrip antennas play a very significant role in today's

world of wireless communication systems. They are very simple in the construction

using a conventional microstrip fabrication technique. These advantages of microstrip

antennas make them popular in many wireless communication applications such as

satellite communication, radar, medical applications, voice services, television, mobile

communication, data transmission, Internet services, education, weather forecasts,

national security, etc…. Now, we focus on communication satellite system. Enlarging

the dimensions of single elements often leads to more directive characteristics (very

high gains) to meet the demands of long distance communication. This antenna formed

by multi elements, is referred to as an array [2]. The signals from the antennas are

combined or processed in order to achieve improved performance over that of a single

antenna. The purpose of using a single antenna for controlling many satellites at the

same time avoiding mechanical movements as well as its inexpensive cost make these

alternative antennas to be considered [3]. Microstrip arrays antennas are limited in that

they tend to radiate efficiently only over a narrow band of frequencies and they cannot

operate at the high power levels of waveguide, coaxial line, or even strip line. In

addition, they are used to scan the beam of an antenna system, increase the directivity,

and perform various other functions which would be difficult with any one single

element.

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In literature, array antennas have been designed in various shapes, sizes and

specific applications. Reference [4], the proposed design consists of two antenna

elements of the following dimensions, width (w) = 37mm, length (l) = 27mm,

substrate thickness/height (h) = 1.25mm. This design has the return loss of -15dB at

2.2GHz and -28dB at 2.45GHz, the gain is 5,07dB at 2.2GHz and 6.45dB at 2.45GHz.

In [5], This paper presents the design of 4x4 rectangular patch array antenna for

the bore sight application of S-band tracking radar with the centre frequency of 2.73

GHz Individual patch having dimension of 43.6x35.3 mm with substrate of

permittivity 2.2 and thickness of 3.175 mm is used. Impedance bandwidth of 250 MHz

for VSWR less than 2 and gain of 18.4 dB with side lobe level better than -6.5 dB have

been achieved

Figure 1: Reference [5]

Research methodology:

In this paper, we have designed the microstrip array antennas with the slot

capable of working in the S-band from 2GHz to 4GHz. The resonant frequency

selected for our design is 2.96 GHz. The antenna is made of a thin substrate for the

application of conformal microstrip array antenna. This paper is proposes the

possibility of prototyping by design and analysis of microstrip array antennas 4×4 and

fabricated on FR-4 with dielectric constant is 4.4 (εr = 4.4).

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2. Design and Simulation of the Antenna

Antenna requirements:

Frequency: S-band 3.0 GHz.

Bandwidth: 80-120 MHz

Directional

Simulation and Fabricate

Substrate: Fr4 Epoxy

Relative permittivity = ε r=4.4

h = 1.6 mm.

Rectangular Patch:

Figure 2: Microstrip line feed

Width of path

w= c

2 f r√( εr+2 )

2

Length (L)

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L=Leff −2∆ L

Effective dielectric constant (ε reff ¿

ε reff=εr+1

2+

εr−12 [1+12

hw ]

−12

Effective length:

Leff =c

2 f r √εreff

Length extension

∆ L=0.412 h( εreff +0.3 )(w

h+0.264)

( εreff −0.3 )(wh

+0.813)Width of transmission line

w t=exp(Z0 (√ε r+1.41 )87 ) 0.8

5.98 h

Where:

f r=3.0 GHz (Resonant frequency).

h=1.6 mm (Thickness of substrate).

ε r=4.4 (Dielectric constant).

c=3.108 m /s (Speed of light).

z0=50 Ω (Impendence of transmission line).

The result is: w = 30mm, L = 23mm, w t = 2mm.

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Figure 3: Singer patch

Feeding network

Figure 4: Feeding network

After calculated single path and feeding network, we have 4 x 4 elements array

antenna:

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Figure 5: 4 x4 array atenna

Figure 6: Port and 3D model

3. Results and Discussions

The simulated antenna has been designed to work at S-band frequency of 2.96

GHz.Firstly, the simulated return loss of the microstrip antenna has been presented in

Figure :

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Figure 7: Simulated return loss of the designed antenna

Table 1: Simulation results of return loss

Parameters Simulation Results

Resonant Frequency 2.96 MHz

Return loss -21.6 dB

Bandwidth at RL = -15

dB81 MHz (2.9GHz-2.981GHz)

As shown in Figure , good return loss result has been obtained, which is -21.6 dB at

2.96GHz. The approximately bandwidth is 81 MHz at RL = -15 dB has been archived.

Obviously, these results meet the requirements in terms of frequency range.

Secondly, the radiation pattern in 2D and 3D representation of the designed antenna

are shown in Figures 8, 9 and 10, respectively and the peak gain is 9.9 dB

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Figure 8: 2D radiation pattern (phi = 0 deg)

Figure 9: 2D radiation pattern (phi = 90 deg)

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Figure 10: 3D radiation pattern

4. Fabrication and Measurement

After obtaining the good results in simulation, an antenna sample has beenfabricated

as shown in Figure 10.

Figure 11: Fabricated antenna

The antenna sample has been measured using the Vector Network Analyzer at the

Wireless Communications Department.

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Figure 12: Connect the antenna to Network Analyzer

The measurement result of the return loss is shown in Figure 12

Figure 13: Comparison between the simulation results

and the measurement result of RL

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Table 2: Comparison between the simulation results and the measurement results

Simulation Measurement

Bandwidth at RL

=-15 dB

81 MHz

(2.9-2.91 GHz)

80 MHz

(2.96 – 3.04 GHz)

As can be seen in figure 13, the simulation and the measurement results have an

agreement. The differences between measurement and simulation are probably

because of some effects, such as the quality and the permittivity of the substrate and

the condition of the measurement.

5. Conclusions

A microstrip antenna S-band satellite communication systems which works at 2.45

GHz has been proposed.The antenna simulation has good results, which matched to

requirement of S-band. An antenna sample was fabricated and measured. The

simulation and measurement have been compared. A good agreement is given.The

designed antenna will befurther optimized to have better results.

REFERENCES

[1] http://www.nasa.gov/audience/forstudents/5-8/features/what-is-a-satellite-58.

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[2] Antenna Theory - Analysis and Design_ Third Edition, Constantine A. Balanis.

[3] Salas Natera, M. A.; Martínez Rodríguez-Osorio, R.; Antón Sánchez, A.; García-

Rojo, I. & Cuellar, L. (2008). A3TB: Adaptive Antenna Array test-bed for tracking

LEO satellites based on software defined radio. 59th InternationalAstronautical

Congress, pp. 313-317, Glasgow. September 2008.

[4] T. K. Sreeja, A. Arun , Dr. J. Jaya Kumari .”An S-Band Micro-strip Patch Array

Antenna for nano-satellite applications”. Green Technologies (ICGT), 2012

International Conference on , 18-20 December 2012.

[5] Anila Kumar Sahu , Manas Ranjan Das “4X4 Rectangular Patch Array Antenna for

Bore Sight Application of Conical Scan S-band Tracking Radar”. Antenna Week

(IAW), 2011 Indian . 18-22 December 2011.

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