“Smart Antenna for 5G Wireless Technology”

Prof. Ashish A. Jadhav, Assistant Professor, Department of Electronics and Telecommunication Engineering, SVERI’s College of Engineering Pandharpur. Email: aajadhav@coe.sveri.ac.in

5G cellular N/W promise to improve various features of mobile communications, supporting enhanced data rates and other mobile services. These benefits will be based on the evolution of 4G LTE technologies and capabilities enabled by 5G. 5G systems will need Smart Antennas to increase coverage, smooth mobility, and minimize the need for hand-over from 5G to 4G RAN. Smart Antennas in 5G is important because it utilizes millimetre wave RF propagation. Smart Antennas enhance 5G application and service mobility by facilitating a more continuous connection. Smart antennas can be manufactured using micro strip patch antennas which are low profile, small size antennas. The methodology proposed need to make use of MIMO (Multiple input multiple output) for advance wireless communication and it is trending since last couple of decades.  Multiband systems, such as Wi-Fi (Wireless Fidelity), Bluetooth, or BLE (Bluetooth Low Energy) are referred as the way of advanced communication technology. These communication technologies are operating at a commonly used ISM frequency band, 2.4GHz. This frequency band is unlicensed and free to use.

The MIMO antenna can be used at multiband frequencies such as 2.4 GHz, 3.3 GHz, 3.6 GHz and 5.5GHz frequencies. This MIMO antenna is designed by using multiple patches on single ground plane, separated by Isolator. Improvement in VSWR, Directivity and Gain can be achieved by using micro strip patch antenna. Return loss of Designed MIMO is below -10dB and VSWR is in between 1 to 2. Isolator can be used to reduce mutual coupling between the patches of MIMO antenna.

INTRODUCTION

Multiple input multiple outputs has several advantages over the conventional SISO (Single input single output) transmit receive method. In terms of channel capacity, SISO faces bottleneck issues which highly degrade the performance of the communication system. MIMO means use of multiple antennas at transmitter for transmission and multiple antennas at receiver for reception of electromagnetic waves. MIMO increases channel capacity as number of elements in MIMO increases. MIMO enhances the bandwidth of communication. It improves the directivity, Gain and Antenna efficiency since it does not require additional transmit power. The ratio of maximum radiation intensity of the subject antenna to the radiation intensity of an isotropic or reference antenna, radiating the same total power is called the directivity and Antenna Efficiency is the ratio of the radiated power of the antenna to the input power accepted by the antenna. The term antenna gain describes how much power is transmitted in the direction of peak radiation to that of an isotropic source. To maintain VSWR in between 1:2, the approximate value of impedance of a transmission line, must equals the approximate value of the impedance of a transmitter antenna, or vice versa, it is termed as Impedance matching. Impedance matching is necessary between the antenna and the circuitry. The impedance of the antenna, the transmission line, and the circuitry should match so that maximum power transfer takes place between the antenna and the receiver or the transmitter

MICROSTRIP PATCH ANTENNA

Micro strip Patch antenna is one of the most popular types of printed antenna. It plays a very significant role in today’s world of wireless communication systems. Micro strip antennae are very simple in construction using a conventional micro strip fabrication technique. Micro strip patch antenna consists of a radiating patch on one side of a dielectric substrate (FR4) that has a ground plane (Cu) on the other side as shown in Fig. 1. The patch is generally made up of a conducting material such as copper or gold and can take any possible shape like rectangular, circular, triangular, and elliptical or some other common shape. The radiating patch and the feed lines are usually photo-etched on the dielectric substrate.

The increase in the number of patches on the substrate, data rate and radiation pattern get increased. The Proposed design is of 6 bands which is resonating at six frequencies and that are 2.51GHz, 4.15 GHz, 6.04 GHz, 2.36 GHz, 3.68 GHz and 5.47GHz,  and it gives VSWR in the range of 1 to 2 and the values of S Parameters which are less than -10 dB.

Two micro strip patches are used to resonate at selected bands of frequencies. FR4 material is used as dielectric substrate between ground plane and the patches. Dielectric constant of FR4 is 4.4 and thickness of FR4 is 1.6 mm. Proposed MIMO antenna for six different bands of frequencies with isolator for mutual coupling separation is shown in figure 3.

S-Parameter:

Micro strip antenna patch-I design resonates at 2.51GHz, 4.15GHz and 6.04GHz. At those three resonating frequencies, values of S-Parameters are -21.19dB, -21.58dB and -16.06dB respectively. Simulation result of 6-Band MIMO antenna with Patch Isolator is shown in Fig. 4.

Fig. 4. S-Parameters of Two Elements, 6-Band MIMO antenna

Patch-2 resonates at 2.36GHz, 3.68GHz and 5.47GHz. At those three resonating frequencies, values of S-Parameters are -40.07dB, -30.20dB and -22.82dB respectively

Bandwidth Enhancement:

Bandwidth of antenna is calculated below -10dB line of S-Parameter plot. Each patch resonates at three different frequencies with three wide frequency bands. Micro strip antenna patch-I design resonates at 2.51GHz (2.3443 to 2.6582 GHz, Bandwidth: 314 MHz), 4.15GHz (4.0092-4.3092GHz, Bandwidth: 300 MHz) and 6.04GHz (5.5941-6.3687GHz, Bandwidth: 775 MHz). Patch-2 resonates at 2.36GHz (2.2158-2.4733GHz, Bandwidth: 257 MHz), 3.68GHz (3.4757-3.8411GHz, Bandwidth: 365 MHz) and 5.47GHz (5.0213-5.7872GHz, Bandwidth: 765 MHz).

Reference Impedance:

If the impedance of the antenna, the transmission line and the circuitry do not match with each other, then the power will not be radiated effectively. Instead, some of the power is reflected back in the form of reflected/standing waves.

Voltage Standing Waves Ratio (VSWR):

The ratio of the maximum voltage to the minimum voltage in a standing wave is known as Voltage Standing Wave Ratio. If the impedance of the antenna, the transmission line and the circuitry do not match with each other, then the power will not be radiated effectively. Instead, some of the power is reflected back in the form of reflected/standing waves. The term, which indicates the impedance mismatch is VSWR. VSWR stands for Voltage Standing Wave Ratio. It is also called as SWR. The higher the impedance mismatch, the higher will be the value of VSWR.

Antenna to resonate efficient must have VSWR value in the range 1-2. The simulated MIMO antenna for six different frequencies is having VSWR between 1 and 2

CONCLUSIONS

It is possible to design an MIMO antenna with Patch Isolator to resonate at 6 different frequencies (2.51GHz, 4.15 GHz, 6.04 GHz, 2.36 GHz, 3.68 GHz and 5.47GHz). S- Parameter at those frequencies are less than -10dB and VSWR is lower than 1.2. Average bandwidth obtained at all the 6-Bands of operating frequency is 300MHz. This MIMO antenna is designed by using multiple patches on single ground plane, separated by Isolator. Isolator is used to reduce mutual coupling between the patches of MIMO antenna.

References

1. http://www.ijircce.com/upload/2018/february/96_21_Design.pdf
2. http://www.ijstr.org/final-print/feb2020/Design-Of-Miniaturized-Two-Elements-6-band-Mimo-Antenna-With-Patch-Isolator.pdf
3. http://www.ijircce.com/upload/2019/december/12_Design.PDF
4. http://www.ijsrd.com/articles/IJSRDV7I20040.pdf
5. http://ijsrd.com/Article.php?manuscript=IJSRDV6I40999