Edge Port Excited Metamaterial Based Patch Antennas for 5G Application

Microstrip Patch Antenna is a narrowband antenna fabricated by etching the antenna element pattern in metal trace of elements like copper bonded to an insulating dielectric substrate with a continuous metal layer on the opposite side of the substrate which forms a ground plane. Electromagnetic Metamaterial is an artificial material that is made up of different types of structural designs on dielectric substrates. In this paper, a broad and elite investigation is being carried out by designing and simulating a single negative metamaterial cell comprising a square split ring resonator. This metamaterial cell depicts negative values of permeability for a specific range of frequencies. These cells show exceptionally great applications in the design of microstrip patch antenna. The substrate of the microstrip patch antenna with a ground plane is loaded with a square split-ring resonator, Conventional and proposed patch antennas are simulated, analyzed, and reported for performance comparison of its parameters. The proposed edge port feed metamaterial based Rectangular microstrip patch antenna and Circular patch antenna designed at 26 GHz resonance frequency useful for 5G applications. Both antennas are designed on RT Duroid 5880 Substrate with 2.2, dielectric constants. The parameters such as bandwidth, gain and return loss of metamaterial loaded rectangular microstrip patch antenna and Circular patch antenna increases considerably compared to conventional antennas. Comparing parameters of both antennas, the performance of the rectangular microstrip patch antenna is found to be better than circular patch antenna.


Introduction
Microstrip patch antennas are being widely used for small wireless communication aerospace applications WiMAX, WLAN, and 5G applications. This antenna is compact shapes like rectangular, circular, and triangular. A patch antenna is designed on a dielectric substrate such as RT duroid 5880 with dielectric constant 2.2. The thickness of this dielectric substrate is 0.5 mm. Lightweight and easy to design and fabricate [1] [2]. It can be designed in different this dielectric substrate is 0.5 mm. If we use a substrate of higher thickness efficiency can be increased, however, as the height increases, surface waves are introduced which usually are not desirable because they extract power from the total available for direct radiation (space waves). The surface waves travel within the substrate and they are scattered at bends and surface discontinuities, such as the truncation of

Double Negative or Left-Handed Metamaterials
They are artificial materials that show negative permittivity permeability and refractive index. These parameters are not found in natural materials. Due to the negative refractive index, phase velocities, as well as group velocity of electromagnetic waves are opposite to each other, and opposite energy flow is observed. Metamaterials having either permittivity or permeability negative are called single negative metamaterials. Equations (1) and (2) are two of Maxwell's equations given to understand metamaterial. µ r and r ε are relative permeability and permittivity respectively.
The plasma frequency is denoted by f p and f mp in Equations (5) and (6) respectively, f 0 is the resonance frequency, f is the frequency of the signal, and damping factor γ which is in connection to material losses. These equations can show microwave range to optical range properties of materials [7] [8].
The SSRR Structure is designed using MATLAB code. In this way, a metal surface is obtained, as shown in Figure 1. The equivalent circuit for SSRR is presented in Figure 2. The inductance of the tank circuit model, Ls is calculated  by assuming the uniform current throughout the loop. The capacitance of the tank circuit is assumed to be the parallel equivalent of the capacitances in each pair of adjacent loops. The SSRR creates a negative µ near resonance frequency.
The magnetic field vector of the incident plane wave is perpendicular to the SSRR, which gives rise to the induced currents resulting in an effective magnetic moment that eventually will yield the negative permeability. The metamaterial supported backward-wave propagation only for the magnetic field directed perpendicular to the SSRR. We have presented the retrieval of parameters of a metamaterial cell using MATLAB to verify the mu negativity of a cell. The inherent feature of CST is used to invoke the CST platform through MATLAB script file [9] [10].

Design of Square Split Ring Resonator Cell
The SSRR is designed on RT Duroid 5880 substrate with a permittivity value equal to 2.

Parameters of SSRR Metamaterial Cell
S 11 and S 21 of SSRR cell are depicted in Figure 3. The lowest magnitude of S 11 indicates that the cell resonates at 26 GHz frequency. The Magnitude of S 11 and S 21 at 26 GHz frequency is 0.2 and 0.78 respectively, which shows that return loss is low at the resonance frequency. Both S parameters are important to calculate the epsilon and mu of the cell. Frequency v/s real and imaginary values of mu are plotted using MATLAB software. Real and imaginary number of Mu of SSRR is shown in Figure 4. The negative mu appears in the frequencies between 24.8 GHz to 4 GHz. Therefore the antenna on metamaterial must be designed to operate within the range of frequencies. Hence, in this project, we considered a resonance frequency of 26 GHz. which is one of the frequency bands used for 5G applications.

Method to Find Parameters of Metamaterial Cell of Complex Structure
It is sometimes difficult to calculate the effective parameters of certain metamaterials, due to the complex structure. In such cases, parameters can be found out from numerical simulations. First, we have to find out the transmission and ref- lection coefficient of the cell based on numerical algorithms, such as (FDTD) and Finite Element Method (FEM). This method also can be used to extract parameters [10]. Equations (7) and (8) where k 0 is the wave vector in a vacuum, defined as k 0 = 2π/ω o , d is the thickness of the substrate, and m is an integer. We can find Z eff and N eff from the above equation. Considering that metamaterial are passive media. That is a real part of the impedance is the positive and the imaginary part of the refractive index is negative. Further є r,eff and μ r,eff can be obtained according to, є r,eff = N eff /Z eff and μ r,eff = N eff Z eff .

Application of Metamaterial in Designing Edge Port Fed Rectangular Microstrip Patch Antenna
Antennas are fabricated using DNG or SNG Metamaterial cells, which is used to increase the performance

RMPA Design on Substrate without Metamaterial
Rectangular microstrip patch antenna. (RMPA) design on RT Duroid substrate with edge port feed at resonance frequency 26 GHz as employed in 5G communication and tested on software FEKO. The width of RMPA is given by Equation (9). Effective permittivity and fringing length delta L are shown in Equations (10) and (11) respectively.
Effective length and actual length are given in Equations (12) and (13) Substrate length and width are given in Equations (14) and (15) respectively. c 0 = Speed of electromagnetic wave [20]. Figure 5 shows the design of Edge fed RMPA without metamaterial on RT duroid 5880 substrates. A Microstrip line is used for feeding the antenna.

Edge Port Fed Rectangular Microstrip Patch Antenna (RMPA) Design on a Substrate without Metamaterial
Design of edge fed RMPA without metamaterials is shown in Table 1      The gain of an antenna is a very important parameter, gain should be very close to directivity so that the efficiency of the patch antenna increases. Figure 8 presents a 3D view of the far-field of an edge-fed patch antenna without metamaterial at 26 GHz. The total gain of the antenna also has been depicted in the figure.   Sub.width (W s ) 6.5

Edge Port fed Rectangular Microstrip Patch Antenna. (RMPA) Design with Metamaterial at 26 GHz Resonating Frequency
Sub.Length(L s ) 6 Feed length(a) 1.55 Feed width(b) 0.53 Figure 10. Shows reflection coefficient v/s frequency graph of RMPA with metamaterial. Figure 11. Smith chart showing impedance matching of RMPA with metamaterial.
almost zero, which matches with source impedance.

Application of Metamaterial in Designing Edge Port Fed Circular Microstrip Patch Antenna (CMPA).
Circular microstrip patch Antennas are designed using DNG or SNG Metamaterial cells, which is used to increase the performance of the system. These cells could substantially increase the gain and radiated power of an antenna. Furthermore, these antennas can improve efficiency-bandwidth performance. Various metamaterial-based antennas can be used for wireless communication [21] [22].

CMPA Design on Substrate without Metamaterial
Circular microstrip patch antenna (CMPA) design on RT Duroid substrate with edge port feed at resonance frequency 26 GHz as employed in 5G communication and tested on software FEKO. The radius of the circular patch of CMPA is given by Equation (15). Where r is the actual radius and F is the effective radius of the circular patch, h is the height of the substrate.   Figure 13 shows the design of Edge fed CMPA without metamaterial on RT duroid 5880 substrates.

Edge Port fed Circular Microstrip Patch Antenna (CMPA) Design on a Substrate without Metamaterial
Design of edge fed CMPA without metamaterials is shown in Table 3 Communications and Network Figure 14 shows the reflection coefficient v/s frequency graph of CMPA. The return loss at resonance frequency is very low (−56 dB), which means the maximum power is radiated by the antenna. Figure 15 Is a smith chart showing impedance matching of RMPA at 26 GHz. The impedance of the patch is zero at the center and increases to words edges. If at the edges impedance is very high then a quarter-wave transformer should be used for impedance matching. Otherwise, a microstrip line will match the 50 ohms port impedance. The graph of VSWR v/s frequency is presented in Figure 16. VSWR of CMPA is 1.0 at 26 GHz.
VSWR (voltage standing wave ratio) is the measure of RF power is transmitted into a load. We would like to cite one example, power amplifier is connected to Figure 13. Design of edge-fed CMPA.  an antenna through a transmission line ideally, there will be no reflections and full signal from the power amplifier will be transmitted to the antenna. However in this world, no system is ideal, there will be some mismatches which will cause some of the signal to get reflected back into the transmission line. If VSWR is one that means the system is perfectly matched.
The gain of an antenna is a very important parameter, gain should be very close to directivity so that the efficiency of the patch antenna increases. Figure 17     GHz. At 26 GHz the impedance is almost 50 ohms, which matches with source impedance. Figure 21 shows the graph of VSWR v/s Frequency. The value of VSWR is 1.0.     A Figure 22(a) depicts the 3D view of the far-field of a CMPA at 26 GHz resonance frequency. Figure 22(b) is a 3D view of the far-field of a CMPA at 25 GHz frequency. Figure 22(c) shows 3D view of a Theta gain of a CMPA at 26 GHz frequency. It is a gain at theta equal to zero and phi equal to 90 degrees and

Simulation Results
The metamaterial cell comprising of SSRR is designed and simulated using MATLAB and CST software, it has been found that the cell with SSRR is a single or mu negative cell that shows negative permeability. The comparison of the parameters of RMPA with and without metamaterial is listed in MHz. And gain is increased by 2 dBi based on simulated results it has been found that the bandwidth and gain of RMPA have improved. VSWR of the conventional antenna is 1.1 and that of the antenna with metamaterial is 1.02 Smaller the value better is impedance matching. The lowest value of VSWR for P. R. Satarkar, R.B. Lohani and with cells is found to be equal to 8 dBi and 9 dBi respectively. So the bandwidth is increased by 300 MHz. And gain is increased by 1 dBi based on simulated results it has been found that the bandwidth and gain of CMPA have improved. VSWR of the conventional antenna is 1.0 and that of the antenna with metamaterial is 1.01.

Conclusion
This paper presents an edge port fed rectangular microstrip patch antenna and