Dept. of Electronics Engineering, Madhav Institute of Technology and Science, Gwalior, India
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In this work, a Rectangular microstrip patch antenna loaded with “Spiral Shaped” metamaterial structure is designed at a height 3.2 mm from the ground plane by using CSTMWS software. The resonance frequency of the designed antenna is 2.1GHz.The 10 dB impedance bandwidth of proposed antenna is 35.1 MHz the Return loss of the proposed antenna is reduced by 35 dB .This antenna is small size, cheap, compact and easy to fabricate, and achieve good radiation characteristics with higher return loss. This antenna can have wide application in a great variety of wireless communication.
Rectangular Microstrip Patch Antenna, Metamaterials, Bandwidth, Return Loss.
In high-performance aircraft, spacecraft, satellite and missile applications, where size, weight, cost, performance, ease of installation, low profile antennas may be required. Presently there are many other government and commercial applications, such as mobile radio and wireless communications. To meet these requirements microstrip antenna can be used. These antennas are low profile, conformal to planar and non-planar Surfaces, simple and inexpensive to manufacturer using modern printed circuit technology, mechanically robust when mounted on rigid surfaces, compatible with Monolithic Microwave Integrated Circuit (MMIC) designs.
The introduction of the so-called metamaterials  (MTMs), artificial materials which have engineered electromagnetic responses that are not readily available in nature, has provided an alternate design approach to obtain efficient electrically-small antenna (EESA)systems.
Calculation of Width (W):
c = free space velocity of light
εr = Dielectric constant of substrate
The effective dielectric constant of the Microstrip antenna to account for fringing field.
Effective dielectric constant is calculated from:
The actual length of the Patch (L)
L = Leff - 2Δ (3)
Calculation of Length Extension
The parameters of rectangular microstrip patch antenna are specified in the Table 1 and dimensional view is shown in figure 1.
|Dielectric Constant (єr)||4.3||-|
|Loss Tangent (tan ∂)||0.02||-|
|Width Of Feed||6.00||Mm|
Table 1: Rectangular Microstrip Patch Antenna Specifications
The Simulated Results of Rectangular microstrip patch antenna is shown in figure 2 and 3.The CST-MWS (computer simulation Technology) was chosen to simulate the structures shown in the figures below.
Then, the “Spiral Shaped” metamaterial structure is placed above the patch antenna at a height of 3.2 mm from ground plane in order to study its influence, and the results are compared with those of the Patch antenna alone. The required specifications of this design are shown in the figure 5.
A Research on [5-6] metamaterial was carried out to understand the fundamentals of the newly discovered substance. The simulated result of rectangular microstrip patch antenna with “Spiral Shaped” structure is shown in figure 6. At 2.1 GHz frequency the simulated rectangular microstrip patch antenna results in Return Loss of -10.5 dB& 12.10MHz Bandwidth while when it is designed with “Spiral Shaped” metamaterial structure at 3.2mm from the ground plane, it shows Return Loss of -45 dB& 31.10MHzBandwidth which shows significant improvement of bandwidth  and reduction in return loss. The Return Loss of the proposed metamaterial structure is reduced by 35dB [9-10] in comparison to the RMPA alone.
Smith Charts  has shown in figure 8 represents the impedance matching of antenna with coaxial cable of 50 ohm.
The “Spiral Shapes” metamaterial structure with Rectangular antenna has been proposed in this paper. The simulated results provide high gain, wide bandwidth and directivity improvement, and increase total efficiency which encourages fabricating the structure. On making some variations in antenna parameter gain can be improved up to desired limit but some practical limitation should be taken care while fabricating the structure on CST-MWS software.