A Novel Approach on Miniaturization of Micros trip Patch Antenna with Loaded Strips

A visankar Roy Praveen Kumar Saurabh Anand Partha Pratim Sarkar Sunandan Bhunia

Dept. ofECE C houdhary Dept. ofECE DETS Dept. ofECE

Haldia Institute of Dept. ofECE Haldia Institute of University of Kalyani Haldia Institute of

Technology, Haldia Institute of Technology, Kalyani, Nadia, WB, Technology, India

Haldia, WB, India Technology, Haldia, WB, India Haldia, WB, India

Haldia, WB, India

Abstract- A novel approach on miniaturization of microstrip

patch antenna with multi frequency operation is proposed in this

article. In this paper we introduce symmetrical strips in both non

radiating side of single layered, single coaxial fed rectangular

microstrip patch antenna. It has been investigated that the strip

loaded microstrip patch antenna radiates multiple frequencies and about 82% size reduction has been achieved. This result has been

found by cutting slot on the patch and taking the ground plane is

almost three times larger than the radiating patch.

Keywords-Microstrip patch antenna, Compact, Multi frequency, Strips

I. INTRODUCTION

Microstrip patch antenna has several attractive features of small size, light weight, easy integration capability with circuits [1-2]. Due to these advantages, microstrip patch antennas are used in portable devices such as mobile phones, laptops etc [3]. To reduce the size of these devices the components used inside them must be reduced. As microstrip patch antenna is one of the most important parts of those portable devices, miniaturization of microstrip patch antenna is thus a very important issue. In addition with the compact microstrip patch antenna it can be used for multi frequency and multiband operations.

Several techniques are used to get compact microstrip patch antenna. Multi frequency or multi band operation can be achieved by cutting the slots of various shapes on the patch and/or on the ground plane [4-11]. S Sarkar et at. [5] has proposed another new technique for miniaturization of microstrip patch antenna by cutting slots on the ground plane. But this structure radiates only single frequency. U Chakraborty et al. [6] has proposed a single layered single fed compact microstrip patch antenna with triangular slot but has found only 46.2% size reduction. Mahmoud N Mahmoud et al. [7] has proposed a structure for multi frequency operation using mutual coupling mechanism between two microstrip patches but size reduction has not been reported and seems to be not remarkable. TWang et al. [8] has reported multi frequency operation with defected ground structure and slotted patch that is also very conventional process. Samiran Chatterjee et al. [9] has proposed a compact microstrip patch

antenna with only 47.4% size reduction by cutting slots on the patch which is not very new concept. S Das et al. [10] shows some basic structures of slotted rectangular patch antenna for multi frequency operation. Sathiyamoorthy Murugan et al. [11] has proposed a dual frequency microstrip patch antenna by cutting U slots on the patch and using air gap between patch and ground plane which is a very complex structure to fabricate.

[n this paper a new technique has been introduced for miniaturization of microstrip patch antenna and multi frequency operation with sufficient gain and radiation characteristics have been found. In the proposed structure two unequal strips in both non radiating side of the rectangular patch have been attached symmetrically. The ground plane has been taken three times larger than the modified patch including strips and coaxial feed has been used for excitation. The reference and proposed antenna are designed on thin substrate of thickness h=1.524mm and dielectric constant Cr =

3. The reference patch radiates 5.7GHz frequency and the proposed rectangular microstrip patch with loaded strips radiates five different frequencies among which minimum is 2.8 GHz. The proposed patch with loaded strips and slots radiates in four different frequencies but the lowest radiating frequency comes down to 2.1 GHz which gives about 82% size reduction.

[I. ANTENNA DESIGN

The width (W) and the length (L) of reference antenna (Antenna 1 ) are calculated from conventional equations discussed in literature [12-13].

fr= 2�J(1:£r) L = Lett - 2�L

w LlL_ (Ereff +0.3)(-;;-+0.264)

Where, -- 0.412 w h (Ereff -0.258)(-;;-+0.8) _(Er +1) (Er -1)

Crett ---+ � 2 2� (1+12�)

(1)

(2)

(3)

(4)

c L ff= --e 2fr,j£reff (5)

Where Leff is the effective length of the patch, �L is the normalized extension of the patch length due to fringe field, Ereff is the effective dielectric constant, other symbols have their usual meanings.

The length (L) and width (W) of the patch of M icrostrip antenna are 14mm and 18mm respectively with substrate of thickness h=1.524mm and dielectric constant Er=3.

The ground plane of Antenna I is three times larger than patch to fulfil the infinite ground plane concept and coaxial cable feed has been used at optimum location. The resonant frequency of Antenna 1 structure is 5.7 GHz with return loss -23.5 dB and bandwidth is 3.2% of center frequency. Antenna 2 structure has been designed with same parameter and in addition of two unequal strips on both sides of reference patch symmetrically. It radiates five different frequencies among which 2.8 GHz is the minimum with very narrow bandwidth. Antenna 3 structure has been also designed with same parameter and same strips on both sides of reference patch loaded with L shaped and triangular shaped slots. It radiates four frequencies among which 2.1 GHz is the minimum and 82% size reduction has been thus achieved. Antenna 1, Antenna 2 and Antenna 3 structure are shown in Fig.I-3.

�1<========1=8 =m=m======�} I- '71_�

9mm 14mm .1 1 Feeding Point [Ji]��

4.67 mm L-__________ �� ______ �I �L_

Patch

Ground Plane Coaxial Probe

Fig.l. Antenna I structure (Reference Patch)

lmm I mm lmm

l m� �.--_____________________ -."., K; i'--L ....... Imm

Patch

h�1_S24 mm

Ground Plan&-

I >mm

rudin, Point [] -�

4.,Smm

Fig.2. Antenna 2 structure (Patch with strips)

1

-.Ie lmm

T

->If-- � lmm l mm

h=1.S24mm

lmm

Patch

Ground Plane

- I , Imm

1 Imm

T

Fig.3. Antenna 3 structure (Slotted patch with strips)

III. RESULT AND DISCUSSION

The reference antenna (Antenna 1) radiates 5.7 GHz with return loss -23.5dB and bandwidth is 182MHz i.e. 3.2% of center frequency. The patch with addition of strips (Antenna 2) radiates five frequencies i.e. 2.8GHz, 5.67GHz, 6.8GHz, 7.1GHz and 7.7GHz with return loss -15.7dB, -19dB, -19AdB, -11.8dB and -12.3dB respectively. The patch with slot and strips (Antenna 3) radiates four frequencies i.e. 2.1GHz, 5.1 GHz, 5.5GHz and 6.65GHz with return loss -l3dB, -15dB, -13.7dB and -17.6dB respectively. The results are shown in tabular form in Table I and Table II. The respective frequency vs return loss graphs are shown in FigA-6.

TABLE I SIMULATED RETURN LOSS RESULTS FOR REFERENCE ANTENNA

Structure Resonant Return Bandwidth Gain (dBi) Frequency Loss (dB) (%)

(GHz) Antenna 1 (Reference 5.7 -23.5 3.2 4.6

Patch)

TABLE III SIMULATED RETURN LOSS RESULTS FOR PROPOSED ANTENNA

Structure Resonant Return Bandwidth Gain (dBi) Frequency Loss (dB) (%) (GHz)

Antenna 2 2.8 -15.7 0.6 4.4 (with strips) 5.67 -19 4.8 6

6.8 -19.4 0.35 7.5 7.1 -11.8 --- 2.5 7.7 -12.3 0.5 1.9

Antenna 3 2.1 -13 0.5 -I (with slots 5.1 -15 1.5 5 and strips) 5.5 -13.7 3.7 5.4

6.65 -17.6 I 4.6

0

-5

A I

ID � -10 (J) g'l

---1

E -15 :::l Q)

0::

-20

-25

A J.. w '" UJ 8 --' E :::J

&1

.1 co '" UJ If) 0 --' E :::J Q)

0:

3

-5

-10

-15

-20

-2

-4

-6

-8

-10

-12

-14

-16

-18

-20

6 Frequency (G Hz) - >

Fig.4. Return Loss graph for Antenna 1

3 5 6 7 8

Frequencv (GHz)--> Fig.5. Return Loss graph for Antenna 2

3 4 6

Frequency(GHz)-->

Fig.6. Return Loss graph for Antenna 3

9

8

The simulated radiation patterns of reference antenna and proposed antenna are shown in Fig. 7 -I I.

(a) (b)

Fig.7. Simulated radiation pattern for Antenna I at 5.7GHz (a) E-Plane (b) H-Plane

(a) (b)

Fig.S. Simulated radiation pattern for Antenna 3 at 2.1 GHz (a) E-Plane (b) H-Plane

(a) (b)

Fig.9. Simulated radiation pattern for Antenna 3 at 5.1 GHz (a) E-Plane (b) H-Plane

(a) (b)

Fig. 10. Simulated radiation pattern of Antenna 3 at 5.5GHz (a) E-Plane (b) H-Plane

.'

(a) (b)

Fig.ll. Simulated radiation pattern of Antenna 3 at 6.65GHz (a) E-Plane (b) H-Plane

In the radiation pattern it has been observed that the 3 dB beamwidth for proposed Antenna 3 is varying between 50° to 100° and the cross polarization level is much below than the co polarization level.

IV. CONCLUSION

A novel method for miniaturization of microstrip patch antenna is proposed in this paper. The proposed antenna is low profile single layered single fed compact multi frequency microstrip patch antenna. Two unequal rectangular strips have been used in both non radiating sides of rectangular microstrip patch to lower the resonant frequency. In most research articles compact microstrip patch antenna has been found by cutting the slots on the patch and/or in the ground plane. Defected ground structure has also been used to reduce the antenna size in some articles. In this experiment compact microstrip patch antenna has been designed by adding rectangular strips and 82% size reduction has been found with good return loss which is very much appreciable than other conventional methods. This proposed antenna also radiates multiple frequencies. The simulated gains for some frequencies are found to be good enough in proposed antenna but for some of frequencies gains are very low, although the gains can be increased by some conventional methods such as using multiple layers, PIF A structure, fractal antenna etc. In radiation patterns cross polarization level are also well below the co polarization level which is highly desirable for the communication purposes. In this paper a new approach for miniaturization of rectangular microstrip patch antenna has been focused. The simulated results are really encouraging and need to verify experimentally.

ACKNOWLEDGMENT

Authors are grateful to Department of Science and Technology, Government of India for supporting research

grant under Young Scientist Scheme by Dr. Sunandan Bhunia vide sanction no. SERB/F/20121 2012-2013 dated 11/07/2012.

REFERENCES

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[3] Zhi Ning Chen, "Antennas for Portable Devices", John Wiley & Sons Ltd,2007.

[4] S.Bhunia, D.Sarkar, S,Biswas, P.P.Sarkar, B.Gupta" K.Yasumoto "Reduced Size Small Dual and Multi-Frequency Microstrip Antenna" , Microwave and Optical Technology Letters, Vol. 50, No.4, pp.961-965, April 2008.

[5] S. Sarkar, A. Das Majumdar, S. Mondal, S. Biswas, D. Sarkar and P.P. Sarkar, "Miniaturization of Rectangular Microstrip Patch Antenna Using Optimized Single-Slotted Ground Plane", Microwave and Optical Technology Letters, Vol. 53, No. I, pp. 111-115, January 2011.

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[7] Mahmoud N. Mahmoud and Reyhan Baktur, "A Dual Band Microstrip­Fed Slot Antenna", IEEE Transactions on Antennas and Propagation, Vol. 59, No. 5, pp. 1720-1724, May 201 I.

[8] T. Wang, Y.-Z. Yin, .I. Yang, Y.-L. Zhang, and .1.-.1. Xie, "Compact Triple-Band Antenna Using Defected Ground Structure For Wlan/Wimax Application", Progress In Electromagnetics Research Letters, Vo1.35, pp. 155-164,2012.

[9] Samiran Chatte�jee, Santosh Kumar Chowdhury, Partha Pratim Sarkar and Debasree Chandra Sarkar, "Compact Microstrip Patch Antenna for Microwave Communication", Indian Journal of Pure & Applied Physics, Vol. 51, pp. 800-807,2013.

[10] S. Das, P.P. Sarkar and S.K. Chowdhury, "Investigations on miniaturized multifrequency microstrip patch antennas for wireless communication applications", Journal of Electromagnetic Waves and Application, Vol. 27, No. 9, pp. 1145-1162,2013.

[11] Sathiyamoorthy Murugan, Elamurugan Sathish Kumar, and Vayanaperumal Rajamani, "Design And Analysis of Double U Slot Loaded Dual Frequency Microstrip Antenna", Progress In Electromagnetics Research Letters, Vo1.45, pp. 101-112,2013.

[12] H. H. Wang, K. Yang, Z. Y. Lei, and C. L. Li, "Broadband Microstrip Antennas Using Coplanar Feed-Line", Progress In Electromagnetics Research Letters, Vol. 20, 129,136, pp-129-136, 20 I I.

[13] E.O. Hammerstad, "Equations for Microstrip Circuit Design", Proc. Fifth European Microwave Conf Pp 268-272, September 1975.