Microstrip Patch Antenna towards Future of Communication

Department of Electronics and Communication Engineering, Sikkim Manipal Institute of Technology, Sikkim Manipal University, Majitar, Rangpo − 737132, Sikkim, India; arunsingh.smit@gmail.com, rbera50@gmail.com Department of Electronics and Communication Engineering, National Institute of Technology, Durgapur − 713209, West Bengal, India; bansibadan.maji@ece.nitdgp.ac.in, riwasgurung1994@gmail.com Indian Journal of Science and Technology, Vol 12(3), DOI: 10.17485/ijst/2019/v12i3/140904, January 2019 ISSN (Print) : 0974-6846 ISSN (Online) : 0974-5645


Introduction
Now days the larger size antenna is replaced by the antenna of smaller size popularly known as patch antenna. It finds its application in most of the fields starting from mobile communication to navigation. These kinds of antennas are inexpensive to fabricate because of its simple geometrical structure and due to this reason it is very popular amongst microwave designer since early days they appear 1,2 . Communication in today's world is changed to wireless communication 3 . The term wireless is closely associated with an antenna as without antenna transmis-sion and reception of data is not possible 4 . In many cases the large size of the antenna makes it improper to be used in many applications. So as a result, attention is given towards compact microstrip patch antennas.
There are many shapes of patch like rectangular, circular, triangular etc. Moreover, hybrid shapes like E shape and H shape antennas are also coming into role now days 5 . The shape variation is simply because of its ease in fabrication as these kinds of antennas are low profile and inexpensive 6,7 . Patch antennas are usually fabricated over a substrate with a conducting ground plane 6 . The size of the patch and that of the substrate should be optimized accordingly so as to achieve the maximum performance. In this study problem is focussed in comparison to dish antennas. The dish operating at 11 GHz is having a diameter of around 60-75 cm. With this dimension the portability of the device is poor.
The method shown in this study for antenna design will help to reduce the cost, size and weight of the antenna as larger dish will be replaced by patch antenna or in other words it will help to make to achieve reducing size, weight and power (SWaP) of the existing one. In this study, for the proposed model the gain achieved is nearly 15dB. It can be further increased if the number of elements is increased.

Methodology
In this study, the antenna is designed in X band particularly at 11 GHz. The relative permittivity of the substrate was 4.4. Width and length of the patch antenna is calculated using conventional formula. This is as shown below: Where c is the velocity of light, for is the resonating frequency, ∈r is the relative permittivity and h is the height of the dielectric substrate.
An important issue in microstrip patch antenna is the effectiveness of feed line. The length of the micro-strip feed can be calculated using (Paul, 2013) length p Where λp the wavelength is related to MPA and ε is the relative permittivity of the substrate used in the design.
Also for width of the feed The effective dielectric constant ∈ eff can be calculated from equation (3) Where, Z in = input impedance, ∈ r = Dielectric constant of the substrate, Height = height of the substrate, and Width = width of the patch.
Since the designs were made for X band at 11 GHz, the width and length of the patch was calculated as 8.30 mm and 5.75 mm respectively. The design schematic of single antenna is shown as Figure 1.
In the proposed model, the size of the ground is also reduced without any effect on the return loss and gain of the antenna. The actual length and width of the ground is given as and

Wg h Width patch
Where Lg, lp, Wg, Wp are length of the ground, length of the patch, width of the ground and width of the patch respectively?

Results and Discussion
Return loss (S11) parameter of single antenna (Figure 1) is shown in Figure 5. The return loss of -29.2130 dB was observed to be at 11GHz.
However, the length and width of ground used in the proposed model is: and Wg h Width patch Equations (6,7) are used throughout the modelling of the patch array.   (Figure 1) antenna. The gain was observed to be 3.89 dB at 11GHz. Figure 8-10 shows the S11 parameter, radiation pattern and gain characteristics of 2x2 patch array antenna (Figure 2) respectively. In the s11 parameter it's observed that the antenna is behaving like a multiband as the return loss is -20.26 dB at 10.48 GHz and -44.895 dB at 11.5 GHz. The gain of the antenna is observed as 10.048 dB @ 11.5 GHz. Its corresponding actual hardware design is shown in Figure 2.

Conclusion
Different configurations of array antenna are shown in this study. Their performance is also shown in the previous section. The improvement is the reduction in ground structure size. The second achievement is the combination of series and corporate feed. This design helps in better current distribution over the patched and also minimizes the return loss to a larger extent. The future scope of this design is it can be further extended 10x10 and even 15x15 to match the gain with that of the dish antenna. Once the gain is achieved experiment can be done for replacing existing dish with that of the patch array. The benefit will be size and cost reduction and can be kept even in a small place. Figure 3. In comparison to previous design the gain is increased by 1 dB. The corresponding hardware design is shown in Figure 3. Multiband feature is observed in this configuration also. Figure 14-16 design shows the different measurement parameters of 4x4 modified patch array antenna shown in Figure 4. Its hardware design is shown in Figure 4. The gain is decreased by a minute value but the current distribution and return loss value improves to a larger extent.