Microstrip Antenna Analysis with Aid of Ultra Wide Band Applications

: Microstrip antenna is an essential choice for Ultra Wide Band (UWB) applications of its light weight, low profile and easy to form antenna arrays. However, the design of microstrip patch antenna bandwidth is greatly affects by the dielectric substrate material (FR4). In this research, the bandwidth enhancement of MPA was designed by minimizing the dimension of Defected GP (DGP) in GP for Ultra Wide Band wireless applications. But, the antenna design complexity increases with the number of an operating frequency band. In this research, the MPA was designed as small as size of 10×13×1.6 mm and operates on frequency band between 3.1GHz to 10.6GHz for VSWR less than 2. The microstrip patch antenna was designed at 3.1GHz to 10.6GHz using High-Frequency Structure Simulator (HFSS) software. The simulation result shows that the proposed microstrip patch antenna obtained <-10dB of return loss from 3.1GHz to 10.6GHz throughout the frequency range. The measured result proves that the proposed microstrip patch antenna has better characteristics to fulfill the requirements of UWB applications.

short-circuit pin, and slots loaded on the patch) [9]. The traditional antenna design scheme requires a complex structure and feeding technique like more layers and parasitic structures.
To overcome the complexity of antenna structure, this research the bandwidth enhancement of MLF is designed by minimizing the length of DGP in GP for UWB wireless applications.
The major aim of the proposed microstrip patch antenna is obtaining wide broad bandwidth with high radiation efficiency and decrease the size of GP structure. Several factors must be taken into account including impedance, physical profile, bandwidth, radiation efficiency, radiation pattern, return loss, and VSWR to select optimized antenna topology for UWB applications by using HFSS software.
This research paper is composed as follows, Section 2 presents an extensive survey of recent papers on GP structure reduction techniques for microstrip antennas. Section 3 briefly described the proposed microstrip patch antenna design. Section 4 presents the experimental result of proposed microstrip antenna and the obtained results are compared with existing antenna designs. The conclusion is made in Section 5.

Literature Survey
The researchers have suggested a number of GP structure reduction techniques for microstrip antennas. Brief evaluations of a few significant size reduction techniques for microstrip antenna are presented in this section. Jain and Shubhi [10] designed Planar Microstrip Patch Antenna (PMPA) with a full GP, which is suitable to operate at 5.5 GHz frequency with 200 MHz bands. The return loss at 5.5 GHz is -29.5dB for inset feed antenna. The maximum gain was 5.7 dB and bandwidth was 200 MHz for entire ground and 210 MHz for the defected GP antenna. This proposed antenna used for the Wireless Land Area Network (WLAN) applications. The return loss of -36.81dB was improved after introducing a pyramidal shape defected GP at the same frequency. The width of the patch and length is high in the proposed method.
Pandhare et al. [11] proposed work was obtained a miniaturized Microstrip Patch Antenna Array (MPAA) utilizing DGS for S-band at 2.2 GHz. First, the patch antenna array was designed at C-band resonates at 5.2 GHz of frequency. The Proposed DGS was integrated into GP of patch antenna array used for size reduction. In this work, the proposed DGS was integrated in the GP of the patch antenna array for antenna size reduction. By using this way, to enhance the gain of proposed miniaturization radiator and the patch radiator was modified to retain its properties of radiations. At the final stage, the resonance frequency of original MPAA shifts from 5.2 GHz to 2.2 GHz and with good performance reduction up to 83 %. The proposed method is obtained -16dB S -parameter, it is not sufficient for effective antenna applications.
Matekovits et al. [12] proposed a mutual coupling reduction between Implanted Microstrip Antennas (IMAs) on cylindrical bimetallic GP. In this work cylindrical bio-metal implant serves as the common ground plane for the conformal antennas. This cylindrical bio metal serves as the common GP for conformal antennas. Then the mutual coupling between two-conformal microstrip antennas was studied and quantified for various spacing between the antennas. Three methods were proposed such as top method, middle method and bottom method to minimize mutual coupling between two -antennas. But, maximum coupling reduction is 7 dB at 75 degree for small angles and the mutual coupling reduction is not significant.
Wei et al. [13] proposed S-shaped periodic DGS to reduce mutual coupling between the antenna elements. This proposed PDGS method significantly disturbs the fields and induces currents in microstrip antenna elements to reduce mutual coupling. The periodic DGS method obtained more than 40 dB mutual coupling reduction in microstrip antenna elements. Furthermore, there is no much significant variance between the simulated and measured Main Lobe Patterns (MLP) in upper sphere space. But, the size of the proposed antenna is more complex.
Painam, Surendrakumar, and Chandramohan Bhuma [14] proposed a size reduction technique when a circular microstrip patch was loaded with a meta-material structure. This

Computation of the width of patch
The width is critical in impedance and power efficiency, it depends upon the operating frequency and height of the substrate. (1) Here, is speed of light (3×10 8 m/s), is permittivity of substrate (4.4), is resonance frequency (6.85 GHz). By using equation (1) the width of patch is13.33mm.

Calculation of effective dielectric constant
Effective dielectric constant is minimum than dielectric constant due to fringing field around the margin of the patch. ( Here, is the height of substrate (1.6 mm), is width of the patch (13.33 mm) and is 4.4. By using equation (2) the effective dielectric constant value is 3.788.

Calculation of effective length
The transmission line method is applicable to infinite GP. However, it is important to have a finite GP for practical consideration. The calculation of effective length has been exposed by the similar result for infinite and finite GP. The effective of the length is expressed in equation (3).
Here, is 3.788, is 3×10 8 m/s and is 6.85 GHz. The effective length is 11.25.

Calculation of length extension and length of patch
The practical approximations used for length extension ( ) is expressed by using equation (4).
Here, is 13.33 mm, is 1.6 mm and is 3.788. The length of extension is 0.843.
The actual length of the patch is expressed by equation (5).
Here, is 11.25 mm and is 0.843. The actual length of the patch is 9.564.

Calculation of GP dimension
The calculation of GP dimension is obtained by using equation (6) and (7).
The rectangular shape is most commonly employed configuration for the patch antenna due to easy to analysis employing transmission line. This proposed MPA-DGP-UWB antenna is realized by etching rectangular slots in GP of the antenna and allows to obtain the desired frequency bands with better performance.

Design of the Microstrip Antenna Using HFSS for FR4
The performance of the proposed microstrip patch antenna is analyzed by HFSS software. The design of the antenna follows four types of the setup such as planar EM design, model, excitation and analysis. By utilizing this HFSS software, this research will compute the gain, VSWR, return loss with no error. The proposed antenna design obtained appropriate results using this software when compared with other software.   Table 1. In this scenario, the simulation and analysis are done for the MPA-DGP-UWB antenna and designed by HFSS simulator.

Performance Metrics
The performance measures which were obtained from this simulation are given as follows:

Return loss (dB)
It is loss of the power in the signal reflected by a discontinuity in a transmission line.
The return loss (dB) is expressed by equation (10).
Here, is the incident power and is the reflected power. The return loss is related to both reflection coefficient and Standing Wave Ration (SWR).

VSWR
The VSWR is the sum of mismatch between antennas and the feeding line. It is calculated for knowing the amount of reflected power and the mathematical expression for VSWR is given in equation (11).
Here, is the Reflection Coefficient (RC).           The main intention of using DGS is to satisfy the return loss of -10 GHz. The return loss of the original microstrip antenna was enhanced significantly from 3.1 GHz to 10.6 GHz with DGS (Table 5). After optimization process, the size of original microstrip antenna has reduced compared to the existing microstrip antenna size.

Network Analyzer
The VNA is a one of the efficient network computing tool that can be utilized to compute the input impedance as a frequency function. Otherwise, it can plot both S11 (return loss) and VSWR based on frequency-dependent function of the antenna impedance. The VNA is shown fig. 13.

Conclusion
In this research, a compact multiband and miniature microstrip antenna for UWB application is presented. This proposed antenna is designed based on a simple DGS through etching slots on GP, so it can be much easier to fabricate. The measured results shows that the obtained return loss is -10 dB and VSWR is lesser than 2 at 3. Schematic diagram of iteration for GP length is 4 mm and GP width is 11 mm Return Loss Plot for GP length is 4 mm and the GP width is 11 mm Figure 9 VSWR Plot for GP length is 4 mm and the GP width is 11 mm Figure 10 Simulated graph of return loss Figure 11 Simulated graph of VSWR   Vector Network Analyzer