Design of Miniature Planar Antennas for 5G Systems

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Introduction
In order to miniaturize planar antennas; we used miniaturization techniques based on metamaterial technologies.These have been gaining momentum in recent years [1,2].The use of these materials offers advantages such as reduction in weight and bulk, which is beneficial for their integration into electronic systems such as telecommunications systems for 5G [3].Our work consists of giving an overview on planar antennas and the mechanism of their operations based on metamaterials, we will propose a design approach for a patch antenna deposited on a monolayer substrate by placing a CSRR cell based on it above.metamaterials working in millimeter wave.Subsequently, we will do a synthesis study to extract the various parameters influencing its electromagnetic behavior.The studied and designed antenna is intended to be used for 5G [4] telecommunications and telephone applications in the [3.3-3.8]GHz frequency band.This article presents a concrete case of the design of a rectangular printed antenna, in order to study, design, simulate, characterize and analyze the various parameters of this antenna.This project consists of developing antennas capable of radiating at the frequency of 3.5 GHz, which could be used in a very large number of applications of telecommunications systems currently for 5G [5,6].
The objective of our work is to miniaturize the dimensions of the initial planar antenna in order to understand the influences of the square CSRR complementary split-ring resonator cells on the planar antennas.First, we modeled and designed the rectangular patch antenna from the dimensions obtained by Maxwell's electromagnetic equations under the Matlab environment.Next, we applied the CSRR cells on the patch antenna to make a parametric study of the different geometric shapes and locations of the CSRR cells on the patch and the ground plane.The various results of simulations of the "S11" reflection and "S21" transmission coefficients are obtained by the electromagnetic software CST are satisfactory and promising.

Characteristics of Planar Antennas
The principle is to design a patch antenna which must operate at the resonant frequency 3.5 GHz, with a reflection coefficient of less than -10dB.The principle is to design a patch antenna which must operate at the resonant frequency 3.5 GHz, with a reflection coefficient of less than -10dB.To perform the various calculations of the dimensions of the rectangular patch antenna, we used the permittivity of the substrate εr=4.3 with a thickness of h=1.56mm [7,8].

Theoretical Calculations of the Dimensions of the Rectangular Patch Antenna
The values characterizing the different elements of the antenna are given as follows: 1. Dielectric permittivity of the substrate (FR-4 "Fire Retardant"): εr=4.
9) Dimension of the transmission line -" 3.05822.Table 1 shows the different parameters of the patch antenna.

Design and Simulation Results of the Rectangular Patch Antenna with Notches
Figure 1a shows a rectangular patch antenna with notches, the latter are used for better adaptation of the antenna to the resonant frequency 3.5GHz.Figure 1b gives the simulation result of the reflection coefficient S11=-29dB as a function of the frequency f=3.51GHz.Figure 1c shows the radiation pattern of the antenna.Figure 1d represents the directivity of the antenna, the angles phi=90° and Theta=270° with a gain of 6.2dB, which shows that the antenna is directional.

Design and Simulation of the SRR Cell
Figure 2 shows the SRR cell and its reflection coefficient S11 as a function of the resonant frequency of the patch antenna.The different dimensions of the SRR are given in Table 1 [9].Figure 2 shows the evolution of the S11 reflection and S21 transmission coefficients as a function of the resonant frequency of the SRR [10].We notice that the designed SRR has a transmission lower than -14dB for a frequency of 3.50GHz and a reflection coefficient of -30.96dB for a frequency of 3.123GHz.

Design and Simulation of the CSRR Cell with 3 Rings with Opposite Openings
Figure 3 shows the 3-ring CSRR cell with opposite openings.The 3 concentric interrupted metallic rings (copper) engraved on a dielectric support (Substrate) [11].

Figure 3. Representation of a 3-ring CSRR unit with opposite openings and its S-parameters.
We notice that the CSRR presents a reflection coefficient S11 of -31dB for a frequency of 3.104 GHz and a transmission S21 of -2.06 dB for a frequency of 3.5GHz, according to figure 3.

Interpretation of Simulation Results Before Adaptation
The parameters of the different antenna configurations depending on the number and the position of the CSRR cells used in table 3.This table represents the different positions and numbers of CSRR cells engraved on the patch and ground plane or both at the same time with the resonant frequency and the reflection coefficient (S11).

Interpretation of Antenna Simulation Results After Adaptation
The parameters of the different antenna configurations depending on the number and position of CSRR cells used are presented in Table 4 which shows the position of the CSRR cells on the patch or the ground plane (PDM) with the resonant frequency and the reflection coefficient (S11).
The results of the S parameters of the previous antennas show band-cut behavior at the 3.5 GHz frequency, corresponding to the resonant frequency of the CSRR cell after optimization and modification of the antenna parameters.
The best optimizations for the different positions of the CSRR cells with their miniaturization rates, their efficiencies and their bandwidth widths are given in Table 5 at the frequency 3.5GHz.Table 6 shows the parameters of the patch antenna after adaptation.

Interpretation of Antenna Simulation Results After Adaptation
The gain values before and after adaptation for the different antenna configurations depending on the number and position of the CSRR cells are presented in Table 7.After simulating the different patch antennas with different positions and numbers of CSRR cells on patch or ground plane or on both sides of the antennas at the same time, we notice that the gain values obtained before adaptation of the antennas are higher than those after adaptation.

CSRR position on Before adaptation
After adaptation patch and PDM

CSRR verticals
Very good reduction in frequency to 3.269GHz with a reflection coefficient of Resonance frequency and desired -28.46dBResonance frequency and desired reflection coefficient -31dB better reflection coefficient -31dB better on patch optimization.optimization.

CSRR
Reduction of the frequency to 3.41GHz with a coefficient of -27.23dBGood Good optimization of the resonant horizontales sur optimization of the resonant frequency and desired reflection coefficient frequency and desired reflection coefficient patch 2CSRR sur patch et Despite the frequency decrease to 3.47GHz the reflection coefficient is very far -17dB.Desired frequency of 3.5GHZ with a good PDM Desired frequency of 3.5GHZ with a good reflection coefficient of -30dB.reflection coefficient of -30dB.
1CSRR sur PDM A resonant frequency reduced to 3.45Ghz with a low reflection coefficient at -25.69dB Close to the resonant frequency but the Close to the resonant frequency but the very low reflection coefficient -23dB.reflection coefficient very low -23dB.

Design and Simulation of 3-ring SRR and CSRR Cells with Openings in the Same Direction
Figure 7 shows the SRR cell.with 3 rings with openings in the same direction and the results of simulations of the Sparameters.Figure 7 illustrates the evolution of coefficients S11 and S21 as a function of the frequency of the SRR.We notice that the transmission coefficient is -15dB at the frequency 3.5GHz and a reflection coefficient of -30.91dB at the frequency 3.113GHz.

Design and Simulation of the 3-ring CSRR Cell with Openings in the Same Direction
Figure 8 shows the 3-ring CSRR with openings in the same direction.The 3 concentric interrupted metal rings are etched on a dielectric support (substrate).

CSRR position on patch
Fréquency (GHz) S-Paramèters (dB) 1 CSRR with 3 rings with openings in the same direction 3.288 -29.66 We notice that the CSRR has a transmission coefficient S21 of -2.07dB at 3.5GHz.

Interpretation of Simulation Results Before Adaptation
The parameters of the different antenna configurations depending on the number and position of CSRR cells used are shown in the table which shows the position of the CSRR cells on the patch with the resonant frequency and the reflection coefficient (S11).

Interpretation of Antenna Simulation Results After Adaptation
The parameters of the different antenna configurations depending on the number and position of CSRR cells depending on the frequency and the reflection coefficient (S11) are shown in Table 10.
Table 10.Value of the reflection coefficient for a patch antenna with 3-ring CSRR cell position with openings in the same direction after adaptation.

CSRR position on patch
Fréquency (GHz) S-Paramèters (dB) 1 CSRR with 3 rings with openings in the same direction.
3.501 -30.088 The results of the S parameters in the previous figures show band-cut behavior around 3.5 GHz, corresponding to the resonant frequency of the CSRR cell after optimization and modification of the antenna parameters.The best optimizations obtained from the different positions and numbers of CSRR cells with their miniaturization rates, efficiencies and bandwidth widths are given in Table 11.
Table 11.Value of the miniaturization rate, the efficiency and the bandwidth for a patch antenna with 3-ring CSRR with openings in the same direction.

CSRR position on patch
Miniaturization rate (%) efficiency (%) Bandwidth (%) 1 CSRR with 3 rings with openings in the same direction 13.79 2.57 9 Table 12 shows the new parameters of the patch antenna after adaptation.

Interpretation of the Gain Results Before and After Adaptation
The gain values for this antenna configuration as a function of the positions of the CSRRs are shown in Table 13 which represents the position of the 3-ring CSRR cells with openings in the same direction on the patch and the gain values before and after adaptation.

CSRR position on patch
Gain before adaptation Gain after adaptation 1 CSRR with 3 rings with openings in the same direction 6.09 5.7 After simulation of patch antennas with different positions and number of CSRR cells on patch, we notice that the gain values before adaptation of the antennas are higher than those obtained after adaptation.

CSRR position on patch
Before adaptation After adaptation 1 CSRR with 3 rings with openings in the same direction Very good frequency reduction at 3.288GHZ Desired resonance frequency of 3.501GHZ with a coefficient of -29.66dB.

Conclusion
It was possible to model a patch antenna using the electromagnetic software Microwave Studio (CST).This modeling made it possible to study the influence of various parameters of the rectangular patch antenna radiation patterns for 5G applications.
The design of the different patch antennas loaded with 3ring CSRR metamaterial resonators with opposite openings and openings in the same direction are set to have a good response at the resonant frequency of 3.5 GHz.The resonance response of these structures varies according to the number and the position of the CSRR resonators, whether on the patch or on the ground plane.
Subsequently, we confirmed that the choice of the position and the number of cells relative to the antenna, is an important condition in order to optimize the level of coupling and to ensure the desired metamaterial effect.The simulation results obtained confirm the obtaining of a better result of reflection coefficients, miniaturization rate, efficiency and gain at the frequency 3.5 GHz for the antennas loaded with 3-ring CSRRs with opposite apertures.The bandwidth varies from 83 MHz to 94 MHz with a reflection coefficient that varies between -25.7 dB and -37.8 dB, depending on the position and number of CSRRs on the antenna.
The goal of this work is to miniaturize patch antennas using CSRR cells embedded on the patch or on the ground plane.Antenna miniaturization technology minimizes the cost and also the gain in materials and surfaces to be used.

Figure 1 .
Figure 1.a. Representation of a rectangular patch antenna with notches.b.Reflection coefficient S11 as a function of frequency.c.Patch antenna gain radiation pattern with notches.d.Patch antenna directivity diagram with notches.

Figure 2 .
Figure 2. Representation of a 3-ring SRR unit with opposite openings and its S-parameters.

Figure 4 .
Figure 4. Coefficient S11 as a function of frequencies for different antennas loaded with 3-ring CSRRs with opposite openings before adaptation.

Figure 6 .
Figure 6.Coefficient S11 as a function of frequencies for different antennas loaded with 3 ring CSRRs with opposite openings after adaptation.

Figure 7 .
Figure 7. Representation of the 3-ring SRR with openings in the same direction.

Figure 8 .Table 9 .
Figure 8. Representation of the 3-ring CSRR with openings in the same direction and the different -S parameters.Table 9. Value of the reflection coefficient for the patch antenna with position of the 3 ring CSRR cell with openings in the same direction before adaptation.

Figure 9 .
Figure 9. Patch antenna with 1 CSRR and its coefficient S11 as a function of frequency.

Figure 10 .
Figure 10.Patch antenna with 1 CSRR and its coefficient S11 as a function of frequency.

Table 1 .
Dimensions of the patch antenna parameters.

Table 2 .
Dimensions of the SRR.
length Ls Substrate height Hs Spacing between rings S S Ring thickness W 5.55mm 1.56 mm 0.15 mm 0.2 mm

Table 3 .
Values of the reflection coefficients for different patch antennas with different positions and numbers of CSRR cells on patch and ground plane.

Table 5 .
Values of miniaturization rates, yields and bandwidths for the different antennas with CSRR engraved on patch and / or PDM.

Table 6 .
Parameters of the patch antenna after adaptation.

Table 7 .
Values of the gain of the patch antenna before and after adaptation.

Table 8 .
Comments on the figures.

Table 12 .
Parameter of the patch antenna after adaptation.

Table 13 .
Values of the gain of the patch antenna before and after adaptation.

Table 14 .
Comments on the figures.