Design Microstrip Antenna DualRAM Patch With Butterfly Slot For Application WiFi at Frequency 5.8 GHz

Arif Fauzar, Muhammad Ibnu Hidayat, Rifki, RifaldoElectrical Engineering Student, Faculty of Engineering, University of Riau

Campus Bina Widya Km 12.5 Baru Simpang Panam, Pekanbaru 28293Email: Fauzararif@gmail.com

Abstrak

Wifi is a technology that is very poluler today. WiFi is an abbreviation of Wireless Fidelity, is a set of standards used for Wireless Local Network (LAN Local Area Networks) whose function is to connect local area networks in a wireless manner. Along with the evolution of telecommunications technology based on wireless technology, then we need for a communication system that can perform high-speed data transmission with good quality. One of the devices supporting wireless communication devices is the antenna. The use and selection of antennas is one of the important factors that affect the performance of the antenna as well as good design and proper installation will ensure the performance of the telecommunications system. Microstrip antenna has the advantages of low profile form, which is easy and inexpensive to produce in mass but has a small gain and bandwidth. This paper discusses the design of the Microstrip antennas Dual-RAM patch for WiFi applications that operate at a frequency of 5.8 GHz .. In this design uses FR4 epoxy material = 4.4 and a thickness of 1.6 mm, is suitable for application of high-frequency antenna. For the simulation in this paper using the software CST Microwave Studio. From the results of the design using CST studio microvawe is obtained in accordance with the specification antenna, with VSWR ≤ 1.5, gain ≥ 2 dB and return loss ≥ 20 dB.

Keywords: Microstrip Antenna, WiFi, Gain, VSWR, Return Loss

I. INTRODUCTION

The rapid development of communication systems, especially wireless communication system. Wireless communication system is a communication system with a transmission medium in the form of electromagnetic wave propagation. The one of wireless communication technology which has now been widely used is WiFi technology. Wi-Fi is a technology that uses electronic equipment to exchange data wirelessly (using radio waves) are widely used for Internet connection high speed. In communication system that uses radio waves such as WiFi the most important part is to optimize the antenna performance that serves to change the signal electricity into electromagnetic waves and then transmit electromagnetic waves through free space or air. And conversely, the antenna also serves receives electromagnetic waves from the free space and then convert it into an electrical signal. The use and selection of antennas is one of the important factors that affect the performance of the antenna as well as good design and proper installation will ensure the performance of the telecommunications system , Microstrip antenna has the advantages of low profile form, which is easy and inexpensive to produce in mass but has a small gain and bandwidth. In this paper, which the problem examined is how to design and realize the microstrip antenna with butterfly slot resulting good quality so that it can be applied to technology WiFi (Wireless Fidelity) with frequency of 5.8 GHz.

II.LITERATURE REVIEW

2.1 Microstrip Antenna

Microstrip antenna is an antenna made of metal layers separated by a dielectric material. Some advantages of microstrip antenna is small in structure, light weight, high gain, high efficiency, wide bandwidth, simple and cheap. Intrinsically microstrip antenna has a weakness in terms of narrow bandwidth . One way to overcome the problem of narrow bandwidth by providing slots in microstrip patch. Microstrip antenna consists of a patch components (strip) radiating metal, dielectric substrate and the ground plane. Permittivity dielectric substrates have dielectric constants (ε r) in the range 2,2 ≤ ε r ≤ 12. Permittivity will affect the size of the antenna are made. The thickness of the substrate is also much smaller than the wavelength in a vacuum (h << λo). Substrate thickness (Hs) generally lies on the range 0,003 ≤ h ≤ 0,005 above the ground plane. A low dielectric constant (ε r) and thickness of substrate will produce a wide bandwidth and high efficiency so that the antenna size becomes larger. Conversely a low dielectric constant and thin substrates will produce a smaller bandwidth and low efficiency and size of the antenna becomes small.

2.2 WiFi

Wireless Fidelity (WiFi) is a conductor media wireless data communications that can be used for communication or transfer of programs and data with the capability of quickly. WiFi communication using IEEE 802.11b standard, only reached the coverage area of no more than hundreds of meters. 802.11 is the IEEE standard for indoor W-LAN.

2.3 Parameters AntennaPerformance of a microstrip antenna can be observed from parameters. Some of the main parameters of a microstrip antenna will be explained as follows:2.3.1. BandwidthBandwidth an antenna is defined as the frequency range in which the antenna performance related to some characteristic (such as input impedance, radiation pattern, beamwidth, polarization, gain, VSWR, return loss) meet standard specifications.Bandwidth can be searched using the following formula:

BW=f 2−f 1

f cX 100 % (2.1)

Description : f 2 = Highest Frequency f 1 = Lowest Frequency

f c = Center Frequency

2.3.2 VSWR (Voltage Standing Wave Ratio) VSWR is the ratio between the amplitude of the standing wave with maximum (|V|max) and minimum (|V|min). In the transmission channel there are two components of the voltage waveform, the voltage delivered ¿ and the reflected voltage ¿. A comparison between the reflected voltage with the voltage delivered is referred to as the voltage reflection coefficient (Г).

Г= V 0−¿

V 0+¿ ¿¿ =

Z L−Z0

Z L+Z0(2.2)

Where ZL is the load impedance and Z0 is a lossless line impedance.Voltage reflection coefficient has a complex value. While the formula to find the value of VSWR is:

S=¿V ∨max¿V∨min = 1+Г

1−Г (2.3)

The best conditions are when the VSWR is 1 (S = 1) which means there is no reflection when the channel is in a state of perfect matching. However, this condition is in practice difficult to reach it. In generally VSWR still considered good is VSWR ≤ 2.

2.3.3. Return loss Return loss is the ratio between the amplitude of the reflected wave to the amplitude of the transmitted wave. Return loss is described as an increase in the amplitude of the reflected wave V 0−¿¿compared with the waves delivered V 0+¿. ¿Return Loss can occur due to a discontinuity between the transmission line to the input impedance of the load (antenna). In the microwave circuit has a discontinuity (mismatched), the amount of return loss varies depending on the frequency.

Г=V 0−¿

V 0+¿¿¿ =

Z L−Z0

Z L+Z0=VSWR−1

VSWR+1 (2.4)

Return loss = 20log10 ¿ Г∨¿¿ (2.5)

By using the value of VSWR ≤ 2 it can be said that the value of the reflected wave is not too large compared with the waves transmitted or in other words, the transmission line can already be considered matching. this parameters value can be one of the references to see if the antenna is able to work at a frequency expected or not.

2.3.4. Radiation PatternThe radiation pattern of an antenna is a graphical statement that describes the radiation properties of an antenna in the far field as a function of the direction. The radiation pattern can be referred to as field pattern when pictured pointing vector. To express graphically the radiation pattern, the pattern can be described in absolute form or in the relative form. Relative form is form a pattern that has been normalized, ie each price of the radiation pattern has been compared to the maximum price.

2.3.5. GainThere are two types of Gain parameters is an absolute gain and relative gain. Absolute gain on an antenna is defined as the ratio between the intensity in a particular direction with the radiation intensity is obtained if the received power by irradiated isotropic antenna. The intensity of the radiation associated with isotropic radiated power equal to the power received by the antenna (Pin) divided by 4π. The absolute gain can be calculated by the formula:

Gain=4 π U (θ ,∅ )P¿

(2.6)

III. METHODOLOGY

3.1. Determination SpecificationsDetermination of the antenna specification suppose to be the antenna simulated to have a value of standards to be met. Antenna will be designed a rectangular microstrip patch antenna which has a specification:

Table 1. Antenna SpecificationsSpecifications Description

Frequency 5,8 GhzVSWR <2 dBRadiation Pattern Omnidirectiona

lGain >2 dBi

3.2. Design and SimulationThe early stages of the design antenna is calculation of value dimensional antenna required for antenna design process. In the design of the antenna, the antenna dimensions will greatly affect the antenna characteristics to be realized. In general, the operating frequency used will determine the physical dimensions of the antenna, the higher the frequency, the smaller dimensions of the antenna. The frequency used in this paper is 5.8 GHz (frequency WiFi).

For the calculation of the dimensions of the antenna first set value:

Table 2. The Specifications Substrate Spesifications Description

Subsrate Material FR4 (Efoxy) = 4,4Subsrate Wide 40.28 mmSubsrate Length 1,6 mmSubsrate Thick 28.05 mmµr 1 (air)

The equations used to calculate the dimensions of the antenna, among others is:

- Calculating the width of the patch (Wp) : ℘= c

2 f 0√ (εr+1)2

- Calculating the effective dielectric constant : ε reff=εr+1

2+

εr−12

[1+12 hW

]12

- Calculating the length : Leff =c

2 f c√εreff

- Calculating the effective length of the patch : Δ L=0.412(W

h+0.264) ( εreff+0.3 )

( εreff−0.258 )( Wh

+0.8)- Calculate the length of the patch (Lp) : Lp=Leff−2 Δ L

3. Simulation of Antenna DesignProcess design simulations using the application software CST Microwave Studio to view the antenna parameters which will be observed. Early process running simulation, parameter values that are the result of simulation without changing the dimensions of the antenna value (the value dimensions of the antenna according to the results of calculations), and get a VSWR values below 2.

Table 2. The results of calculation Dimensions AntennaComponents Symbols Components Dimensions (mm)

Subsrate Wide Ws 40.28Subsrate Thick Hs 1.6Subsrate Length Ls 28.05Patch Wide Wp 13.42Patch Thick Hp 0.02Patch Length Lp 9.34

After the design process is done and it will be the process of running the simulation for get the value of the parameter that will be experienced. The initial results of simulation running without change the dimension values of the antenna (antenna dimension values in accordance with the results of the calculation).

Figure 1. VSWR Value Simulation Results

As shown in Figure 1, if the simulation results not in accordance with the desired specifications (VSWR value is still more than the value of 2, it will be optimized the design of the software application that is used to characterize or adjusting the dimensions of the antenna.

4. Antenna Simulation OptimizationAt the beginning of the simulation with the results of the initial calculation of the dimensions of the antenna without optimized, it can be seen that the antenna has been simulated not work at a predetermined frequency range. Parameter values observed are also not yet reached the prescribed specifications. The dimensions of antenna affects change parameter values were observed. In this paper, changes in the dimensions of the antenna starts from changes in the value dimension for Lp until obtained VSWR value which is less than the value of 2.

Table 3. Patch length shift value (Lp)Dimensi antenna VSWR Return Loss (dB) Bandwith (Mhz) Frekuensi (Ghz)

Wp Lp13.42 9.14 1.02 -39.5 179 5.7613.42 8.94 1.01 -45.88 179 5.7713.42 8.74 1.01 -45,90 179 5.78413.42 8.54 1.02 -38.55 180 5.8213.42 8.34 1.01 -46.00 200 5.80

From Table 3 consists of several graphs return loss, where each graph have different return loss values. Length variation patch made is from 9.14 to 8.34 mm with the decrease by 0.2 mm and a reduction in the fixed parameter is the width dimension of the patch 13.42 mm. Based on simulation results, it is known that the best return loss values obtained on length patches 8.34 mm and has a center frequency at 5.80 GHz with a return loss of -46.00 dB.

5. Simulation Results After OptimizationFrom the results of the optimization, the value obtained optimal antenna dimensions as in table 4 below:

Table 4. Dimensional Antenna Optimization ResultsComponents Symbols Components Dimensions(mm)Subsrate Wide Ws 40.28Subsrate Thick Hs 1.6Subsrate Length Ls 28.05Patch Wide Wp 13.42Patch Thick Hp 0.02Patch Length Lp 8.34

After the optimization process is done on the dimensions of the antenna are obtained the form values of different parameters of the simulation results using the dimension values from the calculation. The simulation results from optimization of antenna is an ideal antenna performance results.

Figure 2.VSWR Value Optimization Result Figure 3. Return Loss Value Optimization Results

Figure 4. Gain Value Optimization Results Figure 5. Polarization Antenna Optimization Results

Figure 2 is a VSWR value optimization results microstrip antenna butterfly slot, it can be seen that the VSWR values obtained at a frequency of 5.8 GHz is 1.01 dB. From the data that has been described above, it is known that in the frequency range from 5.75 to 5.90 MHz, butterfly slot microstrip antenna design capable of working at VSWR ≤ 1.5. This value has needs to be achieved, on the value ≤ 1.9 VSWR or return loss ≤ -10.18 dB. While figure 3 is Return Loss values obtained after the optimization process at a frequency of 5.8 GHz is 46.00 dB. Figure 4 is an antenna gain value optimization results, obtained by a gain of 2.03 dB while Figure 5 is polarization antenna optimization results.

IV. RESULTS AND DISCUSSION

Antena Mikrostrip Patch slot Butterfly (DIRUBAH YA NAK GAMBARNYA PAKE KETERANGAN W,L, H)

(a) Front View (b) Back View

Figure 6. Modeling and Simulation Microstrip Patch Antenna Butterfly slot

With optimal dimensional values, obtained VSWR <2 for the working frequency was observed (Figure 2). With the decline in the value of VSWR, the return loss will also be smaller. The value of VSWR, Return Loss and Gain of the initial simulation results can be seen in Table 5 and the value of VSWR, Return Loss and Gain of the optimization results can be seen in Table 6

Table 5. Parameters Simulation Results

Table 6.Parameters Optimization Results

Parameter (dB) Calculating Result frequency (Ghz)VSWR 1.02 5.76Return Loss -39,5  5.76Gain 2.01  5.76Bandwidth 179 Mhz  5.76

Parameter (dB) Calculating Result frequency (Ghz)VSWR 1.01 5.8Return Loss -46  5.8Gain 2.03  5.8Bandwidth 200 Mhz  5.8

4.1. Effect of Antenna Dimensions Against VSWR & Return LossFrom Table 5, it can be seen that by using the antenna dimensions based on value calculation results obtained produce working frequency range is undesirable. In Table 6 and Figure 7 , center frequency of the working frequency is generated is 5.76 Ghz while the center frequency of the desired operating frequency range of 5.8 Ghz. By using the value of the antenna dimensions have been optimized, value obtained the most optimal dimensions in order to obtain the value of VSWR is less than or equal to a value of 2. It is seen that the value of Wp and Lp will affect the value of VSWR in the frequency range observed. It can be seen when the value of Wp and Lp converted into smaller, then the VSWR values also will be smaller and the frequency of the desired work will be shifted toward higher. So the higher the frequency, the smaller dimensions of antena. Simulation Results obtained by using the value of the antenna dimension is the most optimal results or results in ideal conditions (without loss) VSWR. The value will be affected return loss, because the greater the return loss VSWR values also getting bigger. The desired conditions return loss is small because the smaller the value of the return loss, VSWR value also increases.

2. Effect Dimensions Antenna Againts Gain & BandwidthFrom Table 5 and Table 6 shows the difference between the value of the gain antenna simulation using the results of calculations and dimensions of the antenna dimensions optimization results. Dimensional change was also affecting the value of the gain. Gain value obtained from the simulation results using the appropriate dimension calculation result is equal to 2.01 dBi and gain value from simulation results using an optimized antenna dimensions are at 2.03 dBi. Gain value of 2.03 dBi is the value of the maximum gain of the antenna has been designed. Besides changes in the dimensions of the antenna also affects the amount of bandwidth that is obtained, the simulation results fit the initial calculation result is equal to 179 MHz and the bandwidth of the simulation results using an optimized antenna dimensions are of 200 Mhz

V. CONCLUSION

Based on the results of antenna design and simulation process can be concluded as follows:

1. The rectangular microstrip patch antenna butterfly slot that is designed to work well in the 5.75-5.90 GHz frequency range with a center frequency at 5.80 GHz VSWR ≤ 2 at 200 MHz.

2. The return loss of the simulation results for the frequency of 5.76 GHz at -39.5 dB, for the frequency of 5.77 GHz at -45.88 dB, to 5,784 GHz frequency of -45.90 dB, and for the frequency of 5.82 GHz at -38.55 dB. Return loss of pengkuran results desired frequency is at 5.8 Ghz frequency of -46.00 dB.

3. The value of VSWR of the simulation results for a frequency of 5.76 GHz at 1.02, for a frequency of 5.77 GHz at 1.01, for frequency 5.784 GHz at 1.01, and for the frequency of 5.82 GHz at 1.02. Return loss of Calculating results desired frequency is at a frequency of 5.8 GHz at 1.01.

4. The antenna gain of the simulation results is 2.03 dBi. The change of Antenna dimensions also affect the value of Return Loss, VSWR, gain and bandwidth the smaller magnitude of dimensions of the antenna, the higher the frequency value is obtained, otherwise the larger dimensions of the low frequency antenna so smaller.

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