A Compact L-slot Microstrip Antenna for Quad band Applications in Wireless Communication

Table of contents

1. INTRODUCTION

esign of compact microstrip antenna has become an interesting topic of research in recent years due to the demand for small antennas in wireless communication systems [1][2][3][4][5]. The development of antenna for wireless communication also requires an antenna with more than one operating frequency. Therefore one antena that has multiband characteristic is more desirable than having one antenna for each frequency band. Unlike normal antenna a defected structure introduces discontinuities on the signal plane and disturbs the shielded current distribution in signal plane [6].As a result apparent permittivity of the substrate varies as a function of frequency. The work to be presented in this paper is a compact microstrip antenna design obtained by the insertion of four L-shaped slot on the two sides of the patch.Two inverted slots are inserted on the left side and two slots are inserted on the right side (one inverted and one simple L slot) on the patch (Fig: 2).The work to be presented in this paper is directed towards the reduction of the size of the antenna as well as to operate the antenna in multi-frequencies. The proposed antenna (substrate with ?r=4.4) has four resonant frequencies and presents a size reduction of about 77.3% when compared to a conventional rectangular microstrip patch The simulation has been carried out by IE3D software which uses the MoM method [10]. Due to the Small size, low cost, low weight and multiband characteristics this antenna is a good candidate for application in Wireless communication system.

2. II.

3. ANTENNA STRUCTURE

The configuration of the conventional antenna is shown in Figure 1. The antenna is a 24 mm x 18 mm rectangular patch. The substrate selected for this design is an FR4 epoxy with dielectric constant (?r) =4.4 and height of the substrate (h) =1.5875 mm. Co-axial probe feed of radius 0.5 mm with a simple ground plane arrangement is used at the point (0,-3) where the centre of the patch is considered at point (0, 0).Figure 2 shows the configuration of proposed antenna which is designed with the similar substrate. The antenna is also a 24 mm x 18 mm rectangular patch. Four L-shape slots which are created on the rectangular patch (as shown in the figure 2). The location of the coaxial probe-feed (radius =0.

4. SIMULATED RESULTS

In this section, simulated return loss (of antenna 1 and 2) and normalized E-field and H-field radiation patterns (of antenna2) are shown. The simulated return loss of the conventional antenna (antenna 1) and the proposed antenna (antenna 2) are shown in fig. 3

5. and fig 4 respectively.

In conventional antenna only one resonant frequency is obtained below -10 dB which is 3.725 GHz and the return loss was found to be about -28. The simulated E plane and H plane radiation patterns for antenna 2 are shown in Figure 5-8.

Isolation between co-polarization and cross pola-rization is more than -15 dB for 1.845 GHz and it decreased with the increase of the frequency for 2.59 GHz and 3.29 GHz. 3 dB E-plane beamwidths are found to be reasonably good for all the cases.

6. EXPERIMENTAL RESULTS

The prototype of the antenna 1 (conventional) and antenna 2 (proposed antenna) was fabricated and tested, which are shown in Fig. 9 Comparisons between the measured return loss with the simulated ones are shown in Fig. 13 and 14. The agreement between the simulated and measured data is reasonably good. The discrepancy between the measured and simulated results is due to the effect of improper soldering of SMA connector or fabrication tolerance.

Figure 1.
5 mm) is also same as shown in antenna1.Optimal values of the parameter of the L-slots and their positions are given in fig 2.
Figure 2. Fig. 1 :FFig. 2 :
12Fig.1 : Antenna 1 Configuration
Figure 3.
59 dB with 68(3.693-3.761) MHz bandwidth. For the proposed antenna resonant frequencies are 1.845 GHz, 2.59 GHz, 3.29 GHz, 4.825 GHz and their corresponding return losses are -21.19 dB,-17.69 dB,-21.56 dB and -22.31 dB respectively. Simulated 10 dB bandwidths are 16 (1.837-1.853) MHz, 16 (2.584-2.600) MHz, 40 (3.268-3.308) MHz and 49 (4.803-4.852) MHz respectively. Hence a significant improvement of frequency reduction is achieved in antenna 2 with respect to the conventional antenna1 structure for resonant frequencies of 1.845 GHz, 2.59 GHz and 3.29GHZ.
Figure 4. Fig . 3 :Fig . 4 :
34Fig .3 : Simulated return loss of the antenna1
Figure 5. Fig . 6 :Fig . 7 :Fig. 8 :
678Fig .5. : Simulated normalize radiation pattern at 1.845 GHz
Figure 6. Fig. 10 :
10Fig .9:Antenna 1
Figure 7. Fig . 11 :
11Fig .11 : Measured return loss of antenna 1
1

Appendix A

Appendix A.1 ACKNOWLEDGMENT

We acknowledge gratefully the help provided by Prof. Santanu Das of BESU, Shibpur, West Bengal, India in the form of Network Analyzer measurement facility.

Appendix B

  1. Advanced Engineering Electromagnetic, C A Balanis . 1989. New York: John Wiley & Sons.
  2. Equations for Microstrip Circuit De-sign. E O Hammerstad . Proc. Fifth European Microwave Conf, (Fifth European Microwave Conf) September 1975. p. .
  3. Microstrip Antenna Design Handbook, G Ramesh , P Bhartia , I Bahl , A Ittipiboon . 2001. Norwood, MA: Artech House Inc.
  4. Dualband monopole antenna with L-shaped strips for 2.4/5 GHz WLAN applications. J.-H Gu , S S Zhong , L L Xue , Z Sun . Microwave Opt. Technol. Lett 2008. 50 p. .
  5. Dual broadband design of rectangular slot antenna for 2.4 and 5 GHz wireless communication. J.-W Wu , H.-M Hsiao , J.-H Lu , S.-H Chang . IET Electron. Lett 11th November 2004. 40 (23) .
  6. An equivalent circuit and modeling method for defected ground structures and its Application to the design of microwave circuits, J S Park . Nov. 2003.
  7. Small planar monopole Antenna with a shorted parasitic inverted-L wire for Wireless communications in the 2.4, 5.2 and 5.8 GHz bands. J Y Jan , L C Tseng . IEEE Trans. Antennas and Propag July 2004. 52 (7) p. .
  8. Compact wideslot tri band antenna for WLAN/WIMAX applications. Q Zhao , S X Gong , W Jiang , B Yang , J Xie . Progress In Electromagnetics Research Letters 2010. 18 p. . (References Références Referencias)
  9. A compact microstrip patch antenna for wireless communication. U Chakraborty , S Chatterjee , S K Chowdhury , P P Sarkar . Progress In Electromagnetics Research C 2011. 18 p. .
  10. http://www.zeland.com Zeland Software Inc. IE3D: MOM-Based EM Simulator,
Notes
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Date: 2012-03-15