1 Introduction

Antenna is an interconnection between guided wave and freespace. It consists of elevated conductors which resemble the transmitter or receiver [1]. Antenna exhibits the property of reciprocity, whether it is transmitting or receiving antenna that possesses the same characteristics. Regardless of the nature of the antenna, they possess some basic properties like directive gain, power gain, beamwidth, bandwidth, radiation resistance, polarization and radiation pattern. Antenna application includes fields such as telecommunication, RADAR and biomedical. In order to enhance the gain, array antenna can be used in the system [2]. The array antenna takes the combined or processed signals to obtain the improved performance over a single antenna. In this paper, complete study of microstrip array antenna (MAA) explains the ways to develop the various characteristics of antenna and their application in the field of wireless communication is presented. The array structure is the simple form which is available. Antenna component includes one PCB with radio frequency connector along with the load. Microstrip antenna constructed with low-cost, closed-controlled substrate material. Microstrip antennas flexible in nature, and they can be used for applications required in obtaining pencil beams, fan beams and omnidirectional coverage [3].

2 Structure of Microstrip Array Antenna

2.1 Linear Microstrip Array Antennas

The linear array provides three major feed methods, and corporate feed contains power divider along with transmission lines for all the radiators. The technique is expensive and physically large, and it is wideband in nature. Phased arrays present in corporate feed with phase shifter steer the beam electrically in different directions. Travelling feed contains radiators that are connected to individual transmission line and along the length through line energy decreases. To obtain similar radiation pattern, coupling factors should be made asymmetrical. The remaining energy is captured by the absorptive load. The bandwidth is limited by permitting beam pointing variations. Resonant feed includes radiators that are purposely spaced in multiple of half guide wavelength separated to yield broadside directing beam. It consists of shunt conductance and series resistance as the radiators. Absorptive loads are not used, and radiator coupling factors made symmetrical at the symmetrical power dissemination point known as aperture [3].

2.2 Microstrip Planar Array Antennas

Microstrip planar array antennas are used in applications where there is a need to obtain beam in pencil beam direction and elements of arrays can be designed in different ways. Corporate feed is used to operate every single array element individually. They usually consist of two elements such as network of microstrip lines and patch radiators. The feed line lengths should be the same to achieve beam directing in broadside to antenna array for various frequencies. The planar resonant feed can be used in structures like hexagons, squares and equilateral triangles. The length of the line half of wavelength in medium and generated voltage at the feed for each line is repetitive at the joining. From resonant feed, radiation efficiency is relatively high. The performance can be further improved by accomplishing one-fourth wavelength stub with a short-circuited ground by avoiding spurious radiation along with array boundary. It leads to increased radiation efficiency and reduced side lobes [4].

3 State-of-the-Art Reviews

The study below explains about different antenna array design concepts by using different geometries, material, techniques employed that are used for operating at various wireless communication application bands. Each paper describes a unique technique to obtain improved parameters for antenna such as gain, bandwidth, return loss, VSWR and efficiency. The study helps reader to understand how antenna element and its array geometries lead to get better results in comparison with single microstrip patch. communication applications such as smart vehicles, Mission-critical control applications (Fig. 1).

Fig. 1
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Proposed dimensions and geometry of 5G antenna for dual band

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Yusnita Rahayu and Mohammed Ibnu Hidayat designed antenna array with single, two, four and six elements which resonate at frequency of 28/38 GHz. The gain estimated is 7.47 dBi with −30.7 dB return loss at 28 GHz and 12.1 dBi gain with −34.5 dB return loss at 38 GHz that can be used in 5G wireless communication applications [5] (Fig. 2).

Fig. 2
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Single microstrip patch antenna

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Uzma Uddin, W. Alarm and Md Rashid Ansari suggested the analysis of rectangular microstrip antenna array operating at 5.9 GHz. The return loss obtained is −26.91 dB of side lobe level as −20.3 dB and radiation efficiency as 77℅ with Directivity of 6.826 dB. This designed was analysed for vehicular communication [6] (Fig. 3).

Fig. 3
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Dual-microstrip array antenna

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Prahlada Rao, Vani R.M and P.V Hunugund analysed the effect of electromagnetic gap (ECG) on dual elements array antenna. The antenna array design is such that the slot with square design END ground plane structure and patch with fractal END generates 8.78 dB of gain with −50.21 db mutual coupling. The resonant frequency is used at 5.53 GHz with mutual coupling and −17. 83 db is used for satellite communications [7] (Fig. 4).

Fig. 4
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Tapered slot antenna array with microstrip line SIW transition

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Pengfei Liu, Xiaomi Zhu, Hongjun Tang, Xiang Wang and Wei Hong analysed a tapered slot antenna which is resonating at frequency of 42 GHz. The result estimated is half beamwidth power in H and E planes are 87° and 11° with gain as 0.7 dB that can be used in 5G wireless communication applications [8] (Fig. 5).

Fig. 5
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Single patch grid array antenna

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W.A.W Muhammad, R. Nagh, M. Fjamlos, P.J. Soh, H. Lago analysed rectangular diamond-shaped microstrip grid array antenna operating at the frequency of 28 GHz. The gain estimated is 11.324 dBi with reflection coefficient of −24.08 dB. The antenna can be used in 5G wireless communication applications [9] (Fig. 6).

Fig. 6
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Diagonal fed microstrip patch antenna layout and its current distribution

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S. Latha, P.M. Rubeshanand designed circular polarized microstrip patch antenna array operating at the frequency of 2.4 GHz for 4 element broad side arrays. The gain estimated is 3.2 dBi for single element and 8.0 dBi for array with return loss of −18.1 and −17.3 dB which is suitable for use in WLAN applications [10] (Fig. 7).

Fig. 7
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Single patch antenna element

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G. Mustiko Aji, Md Ammar Wibisono and Munir designed high gain 4 × 4 rectangular patch array antenna with corporate feeding which operates at the frequency of 2.4 GHz. Gain estimated is 15.59 dB with return loss of 19.52 dB, bandwidth of 130 MHz and VSWR of 1.24 for rural area applications [11] (Fig. 8).

Fig. 8
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Expanded view of single radiating antenna element

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Kamil Yauvz Kapusuz, Yakup Sen, MetehenBulut, Iiter Karadede, UgurOguz analysed 8 × 8 phased antenna array with orthogonal feeding for ground plane and bottom layer operate at the frequency of 10.7–12.75 GHz. The gain estimated is 20 dBi with polarization below −10 dB that can be used for mobile satellite communication [12] (Fig. 9).

Fig. 9
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8 × 1 microstrip array antenna in rectangular and circular patch

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Dr. Jagtar Singh, Sunita Rani, Mandeep Singh analysed 8 × 1 rectangular and circular microstrip array antenna with series feed operating at the frequency of 10 GHz. The gain estimated is 10.19 and 11.650 dBi with return loss of −24.36 and −16.36 dB, the efficiency of 88.82% and 87.85% for use in speed detection for traffic management [13] (Fig. 10).

Fig. 10
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Geometry of dual-slot microstrip patch antenna

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Rathindranath Biswas, Asim Kar designed dual-slot microstrip patch antenna array with co-axial feeding having two parallel slots near the edges which operates at the frequency of 2 and 1.982 GHz. The gain estimated is 7.12 dB with return loss of −40.96 dB, bandwidth of 28.7 MHz and HPBW of 76° which is used for microwave and millimetre applications [14] (Fig. 11).

Fig. 11
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Geometry of array with ground plane and its feed point

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Chandan Kumar Ghosh, Susanta Kumar Parvi designed a 2 × 2 microstrip patch antenna array that has two elements placed at a distance of 6.2 cm with co-axial feeding operates at frequency of 2.45 GHz. The gain estimated is 3.4 dBi for single element and 11.80 dBi for array with return loss of −26.30 dB that can be used for WLAN/MIMO applications [15] (Fig. 12).

Fig. 12
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Single element rectangular patch antenna

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A. Asrokin, M. H. Jamaluddin, M. K. A. Rahim, M. R. Ahmad, M. Z. A. Abdul Aziz and T. Married analysed the design of microstrip patch antenna array which resonates at frequency of 5.8 GHz. The return loss estimated is −30.42 dB with 15℅ bandwidth and gain of 16 dB with 9° half power beamwidth for use in point-to-point communication [16] (Fig. 13).

Fig. 13
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Rectangular microstrip antenna (i) side view (ii) top view

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B. Sandhya Reddy, V. Senthil Kumar, V. V. Srinivasan designed 2 × 2 rectangular linearly polarized microstrip patch antenna array with corporate feeding which resonates at frequency of 5.8 GHz. The gain estimated is 9.29 dBi for single element with bandwidth of 340 MHz and 14.3 dBi for 2 × 2 array with bandwidth of 490 MHz for solar power satellite applications [17] (Fig. 14).

Fig. 14
figure 14

2 × 2 MIMO rectangular patch antenna array

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Yusnita Rahayu, Ivan Rafli Mustofa suggested 2 × 2 MIMO rectangular patch antenna array with microstrip feed operates at the frequency of 28 GHz. The gain estimated is 18.5 dBi with return loss of −44.71 dB having an impedance of 1.95 GHz for application in 5G wireless communication [18].

4 Result and Discussions

Table 1 signifies the different antenna configuration and techniques employed in designing antenna array structures. It represents the various microstrip array antenna design structures with different dielectric materials operating at various frequency bands that can be used for different wireless communication applications.

Table 1 Comparative study of different methods
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The Table 1 represents different antenna configurations and what are the gain, return loss values and in which wireless application the antenna array structures can be used. The study shows techniques for improving major parameters such as bandwidth, gain, return loss, efficiency, directivity, coupling and polarization. The Table 1 briefs about array structures, their resonating frequency and application area.

5 Conclusion

This paper is attempted to provide the study of designing antenna array structures which overcome the limitations of microstrip antenna. The microstrip antenna array structures are capable of providing improved gain, return loss, bandwidth, beamwidth and efficiency. The antenna array is designed with different feeding techniques, and operating at different resonant frequencies can be used in various wireless communication applications. This paper elaborates the present research in the use of antenna arrays to meet the required need for increased channel capacity by interpreting how an array can be used in various wireless communication systems. The study shows theoretical, experimental, and computer-simulated studies that show the usefulness of such systems.