Antenna Co-planar Array of X-band frequency 9.4 GHz for Radar

Yussi Perdana Saputera1, Yuyu Wahyu1, and Mashury Wahab1

1Research Centre for Electronics and Telecommunications of The Indonesian Institute of Sciences (RCET-LIPI), Sangkuriang road, Building 20, 4th Floor, Indonesia

Yussips@gmail.com

Abstract - In this paper, carried out research on the development of radar antenna for X-band, with a resonant frequency of 9.4GHz. Antenna designed using coplanar array, the module is designed radiating patch of 4, 4 co-planar patch on the left side of the main and 4 co-planar on the right side of the main patch. Bandwidth resulting from the simulation is 677.8MHz, at a frequency of 9.0815GHz - 9.7953GHz. In the realization of Bandwidth is 419MHz. The resulting simulated VSWR at a frequency of 9.4GHz is 1.0256 and 1.056 for the realization of results. The resulting gain is 13.38dBi for simulation, and 14.1dBi for realization.

Index Terms — Antenna; Radar; co-planner and Bandwidth

I. INTRODUCTION

Radar is Electronics and Telecommunication technology has an important role in the defense, surveillance, observation and battle a State. Currently, Indonesia with research institutions (The Indonesian Institute of Sciences - LIPI) has succeeded in making radar LPI (Low Probability of Intercept) is installed on warships Indonesia republic, and coastal radar. Radar antenna is designed using the method of planar arrays with the rectangular radiating patch 64 patch arrays stacking horizontal and 4 vertical array patches. It aims to generate antenna specifications:

• Frequency: X band (9.37 – 9.43GHz) • Microstrip Patch array with gain ~ 30dB. • Dual antenna configuration for transmit and receive. • Bandwidth : > 60MHz • Horizontal Beamwidth: < 1 degree. • Vertical beamwidth: < 20 degree.

Fig. 1. LPI radar antenna made in Indonesia with Radom, in Indonesian

Warship * Document Radar RCET-LIPI.

With the advancement of science and technology, research done by maximizing the quality of the radar antenna, ranging from the dimensions and performance of the radar antenna. In this paper designed and manufacturing antenna that has a large gain and wide bandwidth, with increasingly smaller dimensions. Using methods generated coplanar with the smaller dimension.

II. BASIC THEORY

A. Basic Concept of Antenna The antenna is a part of a wireless telecommunications

system used to transmit or receive radio waves “The IEEE Standard Definitions of Terms for Antennas” (IEEE Std 145-1983). Based on these definitions it can be concluded that the antenna can function as a receiver and a transmitter which is the intermediate medium between the guided waves with wave-free. Guided wave is a wave with a slight loss in the transmission line, while the vacuum wave is a wave that is emitted into free space so as to form layers. Guided wave which flows along the transmission line, waves radiated into vacuum. Transition region between the guided wave and wave vacuum can be called antenna [1].

Fig. 2. Basic Concept of Antenna [1].

B. Microstrip Antenna

Microstrip antenna is an antenna in the form of a thin board and capable of working at very high frequencies. In its most basic form, a microstrip antenna consists of a field (patch) radiating on one side of the layer (substrate) dielectric which has a base plane (ground plane) on the other side [2], [3].

Line Electromagnetic field

Transmission Line

Signal Generators

Guide Wave Transition area Or Antenna

Free space wave radiation

978-1-4799-7447-4/14/$31.00 ©2014 IEEE

Fig. 3. Microstrip field structure

C. Microstrip line

Fig. 4. Transmission line structurThe formula for calculating the width of t

is given by the following equation [2], [4]. With εr is the relative dielectric constant a

√

The magnitude of the relative dielectric c1, expressed by the following equation,

/ .

The magnitude of the relative dielectric c1, expressed by the following equation,

D. Microstrip Antenna Array The antenna array is an arrangement of

antennas. In a microstrip patch antenna, aarray is part of the patch. To form the directcertain, required field of each element of tconstructively in the desired direction damaging the other direction [5].

E. Rectangular Microstrip Patch Antenna

Here are some of the calculations urectangular-shaped microstrip antenna:

Specifies the width of the patch (W) [6]:

.

e. the microstrip line

. . (1) and B,

(2)

constant for W/h <

(3)

constant for W/h >

. (4)

f several identical are arranged in an tivity pattern has a the array interfere and interfere in

used to design a

(5)

The length ΔL formulated as ∆ . For the resonance frequenc

length is given as:

F. Microstrip indentation (Curv

Fig. 5. CurvedOne way to reduce the retur

curved bend. Douville and Jamfind the optimal size of the indoptimal size of the indentation

. . G. Matching Impedance

Matching impedance a methunify the two are not the sameimpedance line (Z0) and the loa

Transformer λ / 4 impedancproviding a transmission line wtwo transmission lines that channel length λ / 4 is equal to

With λg is the wavelength adielectric material can be equation [4]:

With λ0 = wavelength in free

H. T-junction

T-junction power divider is the antenna array configuratechnique that can support thematching, especially for micros

s follows:

. .. . (6) cy f0 indicated, the effective

(7)

ved Bend)

d bend Design. rn loss in the curve is to use a mes has been doing research to dentation. They found that the is :

· . (8)

hod or technique that is used to e impedance, the characteristic ad impedance (ZL) [4]. ce matching is a technique by

with impedance ZT between the do not match. Transformers [4]:

(9)

at which the magnitude of the calculated by the following

(10)

e space (m),

(11)

a technique commonly used in ation. Power divider is one e transmission line impedance strip antenna array [5].

Bend

Fig. 6. T-Junction for microstrip.

III. ANTENNA DESIGN AND SIMULATION

Antenna design is using materials Duroid 5880, with εr 2.2. Based Calculation using the formula to the optimum value for W = 8.8 mm and L = 8.9 mm.

A. Design

Fig. 7. Antenna front design.

Fig. 8. Antenna back design.

B. Simulation Results

From the simulation results obtained return loss at frequency of 9.4GHz = -37.762dB. By using a microstrip line curved bend on each side. Curved bend in a microstrip transmission line can improve the quality, so it will be matching impedance, resulting VSWR and return loss gets smaller. Without curved band, at a frequency of 9.4GHz = -35.81dBi.

Fig. 9. Simulated return loss results.

In the coplanar method, an important variable in determining the optimum results, by adjusting the distance (d) the main radiating patch and co-planar radiation. In this research, conducted experiments range from: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1 mm. can be see figure 10.

Fig. 10. Experimental distance (d) Co-Planar least Optimum.

Based on the results of the experiment by shifting the distance, the optimum distance obtained with most good VSWR values at a distance of 0.6 mm. VSWR values generated 1,002. It can be see figure 11.

Fig. 11. Experimental result distance (d) Co-Planar least Optimum.

Fig. 12, Experimental width Co-Planar least Optimum.

In addition to the high setting method, co-planar width used must be optimized for the 9.4GHz frequency. In research conducted the most optimum width of 2.7 mm.

Fig. 13. Experimental result width Co-Planar least Optimum.

Fig. 14. Simulation results Gain Antenna.

The simulation results can yield a gain of 13.28 dBi, in addition to the main patch which resulted in a gain, the co-planar also produces gain, this is due to the stepping field of radiating patch to the co-planar.

Fig. 15. Display radiation from co-planar patch.

Fig. 16. Vertical radiation pattern simulation results.

Fig. 17. Vertical radiation pattern simulation results

The resulting beamwidth of 4 radiating patch compiled with the co-planar is 17.6 ◦.

IV. REALITATION

Fig. 18. Antenna front view.

Fig. 19. Antenna back view.

Based on results of fabrication, measurement, and VSWR values obtained at the frequency of 9.4GHz is 1.056.

Fig. 20. Measurement VSWR.

VSWR and return loss values resulting from measurements

using a network analyzer is not much different from the VSWR resulting from the simulation.

Fig. 21. Measurement return loss.

Fig. 22. Vertical radiation pattern measurements.

Measurements of the resulting radiation pattern measurements produce the same wide beamwidth with the simulation results, with the amount of 3dB beamwidth of 18 ◦, and the resulting gain of 14.1dBi. For this measurement, we use horn antenna with the gain of 12dBi and the reference gain of 15.22dBi.

The steps for measurement are as follows: a. The antenna under test (AUT) is used as a receiver

that receives the transmitted signal from the transmitting antenna. The measured levels at the spectrum analyzer will be recorded. Ten sample levels were recorded.

b. Replace the AUT with a dipole antenna λ/2 as a reference antenna with transmitted signal level is the same as the one in step (a). Record the measured levels at the spectrum analyzer.

c. Compare both recorded data with the following equation:

GAUT(dBi) = PAUT(dBm) – Pref(dBm) + reference antenna gain Where, GAUT(dBi) = antenna under test gain (dBi) PAUT(dBm) = received power level at the AUT Pref (dBm) = received power level at reference antenna.

TABEL 1 COMPARISON OF SIMULATED AND MEASURED ANTENNA GAIN.

Measured Gain Simulated Gain ±14.1 dBi 13.28 dBi

V. CONCLUSION

Based on the research results of a co-planar array antenna, antenna radiating material with the addition of a method that is not powered, the corresponding positions can produce a wide bandwidth with greater gain. In the design of the radar, it takes the gain > 30dBi, to get gain > 30dBi, co-planar antenna design required only 48 patches radiating horizontal and 4 vertical radiating patch with a total length of 1 meter. As well as using the combiner as a whole system antenna combiner.

ACKNOWLEDGEMENT

This project was supported by Dr. Mashury Wahab and Dr. Ir. Yuyu Wahyu, MT. as coordinator of RADAR project on Research Center for Electronics and Telecommunication -Indonesian Institute of Sciences (RCET-LIPI), and was performed in cooperation with the University of Indonesia for the use of simulation software. The funding for this research comes from the internal research funding of the RCET-LIPI.

REFERENCES [1] Kraus, J. D.,”Antennas”,2nd ed., Mc.Graw Hill, New Delhi, 1988. [2] Mashury, W., Yussi, P. S., Yuyu, W., Design and Development of

Microstrip Planar Antenna for S-Band Radar, MICEEI, Makasar, 2012. [3] Wisnu,“Desain dan Realisasi Susunan Antena Mikrostrip 12,15 GHz

untuk Aplikasi Mobile VSAT pada Frekuensi Downlink Ku-Band”, Laporan Tugas Akhir Teknik Telekomunikasi Institut Teknologi Bandung, 2009.

[4] Fahrazal, Muhammad,“Rancang Bangun Antena Mikrostrip Triple-Band Linier Array 4 Elemen untuk Aplikasi Wimax”, Laporan Tugas Akhir Teknik Elektro Universitas Indonesia, 2008.

[5] Hanafiah, Ali,“Rancang Bangun Antena Mikrostrip Patch Segiempat Planar Array 4 Elemen dengan Pencatuan Aperture-Coupled untuk Aplikasi CPE.pada Wimax”,Laporan Tugas

[6] Mashury, W., Yussi, P. S., Yuyu, W., Research and Development of Transportable Coastal Radar at S-band Frequency with FM-CW Technology for Supporting C4ISR, EEIC, Hingkong, 2013.

[7] Yuyu, W., Yussi, P. S., dan I. D. P. Hermida, “Array Planar Antenna Using Thick Film on Alumina Substrate for X-band Radar”, ICRAMET, Surabaya, 2013, in Proc. ICRAMET, Surabaya, 2013, pp. 30 – 34

[8] Research documents radar LPI (Low Probability of Intercept) Research Center for Electronics and Telecommunications - LIPI Bandung, Indonesia.