International Journal of Electronics and Computer Science Engineering 933 Available Online at www.ijecse.org ISSN- 2277-1956 ISSN 2277-1956/V1N3-933-939 Aperture coupled stacked patch antenna for dual- band Rajesh Kumar Vishwakarma 1 , Sanjay Tiwari 2 1 Department of ECE, JUET, Raghogarh, Guna, 2School of Studies in Electronics, Pt. Ravishankar Shukla University, Raipur E-mail: rkv.786@gmail.com1 drsanjaytiwari@gmail.com2 Abstract-Microstrip antennas (MAS) are very useful antenna where low profile antennas are required. They are most popular due to their small size, low cost, light weight. The first aperture coupled microstrip antenna was introduced in 1985 by D M Pozar. Aperture coupled antenna is a particular antenna with high gain and wide bandwidth. This paper presents aperture coupled stacked patch antenna using air gap variation. The variation of air gap [2mm to 6mm] has been done between single patch antenna and an aperture coupled antenna. The main advantage of this antenna to increase the band width of the antenna as compared with single layered patch antenna. The resonant frequencies changes with air gap variations. The feed can be done either a conventional coaxial probe or through a coupling aperture in the ground plane as we done. This antenna works well in the frequency range (2.9 GHz to 6.0 GHz). The measured return loss exhibit an impedance bandwidth of 35%.The input impedance and VSWR return loss have been measured with the help of Network analyzer. [Agilent E8363B A.04.06] From the measured result it is found that the value of VSWR corresponding lower resonance frequencies increases from 14 to 2.2 with increasing air gap variation where as at the upper resonance frequencies is also increased from 1.8 to 2.3. Key words: Aperture coupled microstrip antenna, Dual-band antenna, Network analyzer, Microstrip line feed 1 INTRODUCTION In recent year the use of microstrip antenna has become quit popular because of their properties such as low profile, light weight, compact and conformable is structure and easy to fabricate[1]. The aperture coupled microstrip antenna first proposed by Pozar [2] in 1985 has a number of advantages over other feeding method involving galvanic contact between the antenna and feed line. The aperture is usually centered with respect to the patch where the patch has its maximum magnetic field. A simple technique for changing the resonant frequencies with out resulting to a new antenna [3-4]. The idea is introduce an air gap variation between the single patch and aperture coupled microstrip antenna. The air gap variations affect the resonant frequencies. The resonant frequencies can therefore be tuned by the variation of air gap. The band width will also increases particularly due to the increases in the height of the dielectric medium. A number of experiment and theoretical structure have been carried out to analyze and design aperture coupled microstrip antenna. Full wave analysis using the method of moments has been used to determine the various antenna parameters [5-8]. A transmission line [9] and cavity model [10] have been proposed as efficiently analysis and design method. Recently an effect of the different shapes aperture coupled microstrip slot antenna [11] and circularly polarized aperture coupled microstrip antenna with resonant slot and a screen was proposed [12]. Optimum design of an aperture coupled microstrip patch antenna describe in details [13]. An Introduction of aperture coupled microstrip slot antenna with microstrip line feed has been discussed [14]. In this paper a simple but accurate design method from air gap aperture microstrip antenna is presented. The dual-band operation of air gap aperture coupled microstrip antenna are useful in many application such as dual-band transmit receive models for space vehicles. II ANTENNA DESIGN