Stacked Two Layer Dualband Antenna for Wireless Applications

Author Name(s): Savita C. Raut
Author Email: savitasonukale@Somaiya.edu

Abstract

This   paper    proposes    a   Stacked    Two   Layer Rectangular Microstrip Antenna (RMSA) structure for Wireless applications in IEEE 802.11 a/ac/n. The proposed antenna consists of two rectangular patches fabricated on two different layers FR4 substrate, separated by an air gap. An Upper patch acts as radiating antenna which is parasitically coupled with lower patch. The Lower patch is fed with 50 ohms coaxial cable. The antenna is simulated using Method of Moments (MoM) based IE3D software. The proposed structure effectively covers two bands 4.98GHz-7.51GHz and 8.35 GHz – 9.09 GHz. The simulated VSWR is < 2 over the entire range in both the frequency bands. The radiation patterns show the suitability of the Antenna for wireless applications.

Keywords

Dual Band, RMSA, Upper/Radiating Patch, Lower/Feed Patch, IEEE 802.11, Air Gap

Introduction

Broadband microstrip antennas are widely used in many wireless applications. The microstrip antenna has inherently low bandwidth. Many techniques have been reported to increase the bandwidth of microstrip antenna [6].These techniques include monopole microstrip antenna and inserting slots in in regular shaped patches. Several structures have been proposed for monopole configurations and slot antenna [1-3]. Bandwidth can be increased by making use of thicker substrates and lowering the dielectric constant [6].Use of thick substrates increases the probe length of feed probe, which deteriorate the antenna performance due to spurious radiations from feed-probe. Making use of air gap in multi-layer configuration ensures increase in height of the antenna and reduction in effective dielectric constant. Multilayer antenna structures are also reported along with slotted patch [4-5].Thus many complex antenna structures have been reported to cover wideband for WLAN applications. This paper introduces a simpler RMSA structure in stacked configuration. The use of air gap between the two substrate layers yields wide impedance bandwidth with the return loss well below -9.5 dB (VSWR < 2) over the entire range.

Conclusion

Proposed Antenna is low profile and can be easily fabricated using commonly available FR-4 substrate. The parametric study of the antenna is also carried out to investigate the effect of air gap. The simulation results show good agreement with the return loss of -15.57 dB, -19.35 dB and -15.37 dB at the resonant frequencies of 5.33 GHz, 7.05 GHz and 8.7 GHz respectively. The Antenna exhibits a wide band operation with VSWR bandwidth of 2.53 GHz (4.98 – 7.51GHz) in band-1 and 740 MHz (8.35 – 9 GHz) in band-2. The antenna covers part of C-band and X-band frequency ranges. Thus the proposed antenna covers wide range of applications such as WLAN and C and X-band applications .The Future work will be focused on the modifying the parasitic patch the to investigate multiband and wideband operations.

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