Various types of wireless communications antennas have been widely used in recent years, because high data rate services are most required . Wi-Fi is commonly used indoors and outdoors to provide wireless connectivity to end users of this system such as routers and wireless repeaters. The efficiency of these devices depends on the antenna capacity that determines how the wireless network covers efficiently. The traditional STDA is used in many mobile communications base station applications due to its ability to operate with lower mutual coupling losses and to provide greater gain. The series-fed two dipoles array antenna which consists of two dipoles with different lengths and truncated ground plane which are further connected in series through a parallel strip line, which is chosen from different types of broadband antennas. This kind of antenna is used in mobile communication in a wide range of applications such as base station antennas, phased array antennas, printed dipole with an integrated balun, a printed dipole pair, a double dipole antenna, a planar, almost yagi, a two layer, printed dipole and a trapezoidal dipole antenna due to their balanced gain of the wide bandwidth. In most cases the antenna size is very difficult to reduce because an antenna size often requires total control over the performance of wireless devices .
There are several types of antennas designed for Wi-Fi applications through different mechanisms. Parametric evaluation of the log-periodic dipole array antenna (MLPDA) microstrip is performed using the transmission line's corresponding circuit. Hence, this MLPDA antenna is ideal for wireless C band applications such as Wi-Fi and wireless applications with a 5GHz band. The thickness of the substrate is 1.6 mm, and its dielectric constant is 4.2. Gain of the antenna is 4.8 dBi . For multi-3G/4 G applications, a Quasi-Antenna with a modified bow-driver has been developed. The measurements show that the antenna has a return loss of 10 dB, 80.4 percent of the bandwidth between 1.45 and 3.4 GHz, because the antenna is constructed using the FR4 substratum with a dielectric constant of 4.2. Measured gains in all the bandwidth are greater than 4 dBi . A dual-band series dipole pair antenna is constructed using proximity-coupled strips and split-ring resonator controllers. The antenna provides dual-band characteristics with the 1.56–1.63 GHz and 1.68–2.87 GHz frequency bands. This antenna comes with VSWR < 2. The antenna gain ranges between 5.9 and 7.5 dBi. The antenna is designed on FR4 substrate. .
The linear array of mutually coupled parallel dipole antennas has been designed with desired side lobe level and return loss. The dipole antenna has an omnidirectional radiation pattern, and it achieves a return of 25dB. The antenna is built using a 1.6 mm height FR4 substrate . Log Periodic Planar Dipole Array Antenna, constructed on the FR4 substrate, has a maximum gain of 7.5 dBi between 3–6 GHz range . A series-fed two-dipole array antenna using nearby Parasitic Director for bandwidth and gain enhancement has been developed. This performance is compared to the traditional STDA antenna that operates in a 1.7–2.7 GHz frequency band with a gain of > 5 dBi. A VSWR < 2 is achieved in this antenna which satisfies the condition . A compact ultra-wideband planar printed Quasi-Yagi antenna has been designed for water detection in the Egyptian Desert. Its bandwidth extends from 47 to 150 MHz with 45% size reduction and the gain of the antenna was around 4.5 dBi. A series-fed dipole pair broadband antenna with parasitic strip-pair director has been developed. The performance is compared to the performance of the traditional SDP antenna generated on a FR4 substratum. The antenna frequency was 1.63–2.97 GHz; the antenna gain was 5.6–6.8 dBi and 58.26 per cent performance . The design of a band-notched broadband series-fed two dipole array antenna has been simulated and analyzed. To get a band rejection the WLAN band was conducted in 2.4–2.484 GHz. Compact series-fed two dipole array antenna has been designed by using top-loaded components . A size-reduced STDA is achieved, which covers a frequency band from 1.7 GHz to 2.7 GHz with a gain of > 5 dBi. Conventional STDA has a bandwidth of 48.7 percent from 1.68–2.76 GHz and a reasonable gain of 5.6–6.0 dBi compared to the proposed antenna parameters. .
A series-fed two dipole-array antenna has been modified to get a reduction in size. The antenna covers at 1.7–2.7 GHz frequency range, with a 5 dBi gain. The antenna had a bandwidth of 49.7 per cent. The frequency ranges from 1.68–2.79 GHz and the gain range from 5.86–6.13 dBi . A wide scanning tightly coupled wideband dipole array is constructed. The architecture adopts an Integrated Balun. The size, weight, cost and even compared with normal feeding techniques are substantially reduced. By removing bulky external baluns, the bandwidth is simultaneously increased by over 30 per cent. This antenna has low <-20dB cross-polarization over most channels, in a dual-polarization configuration. Measured results for a prototype 8× 8 module antenna display good simulation agreement . For improved gain and front-to-back ratio, a series-fed two-dipole array antenna was designed using bow-tie components. The frequency band, with the gain > 5 dBi, ranges from 1.7 to 2.7 GHz. This compares its efficiency to that of the STDA antenna. The antenna has a bandwidth of 48.8 per cent in the 1.69–2.78 GHz range. Its gain ranges from 5.8 to 6.3 dBi and the front-to-back ratio ranges from 14 to 17 dBi with a decrease of 10 percent in the overall antenna width .
A dual-band loop-loaded printed dipole array antenna which is incorporated with a balun structure has been designed. It is designed with loop-loaded printed dipole antenna array. It operates in a dual-band at 3.0 and 5.5 GHz. To achieve balanced and matched excitation to the antenna array. A new corporate balun/feed structure is employed . A double-layered printed dipole antenna with parasitic strips has been developed. This antenna has 75% impendence bandwidth, VSWR < 2, operates between 2.5 and 5.5 GHz bands. Moreover, stable radiation patterns with 6.3–9.1 dBi peak gain and low cross-polarization are obtained within the bandwidth. An eight-element printed dipole antenna array is assembled and measured, showing a good performance in the array . A double-printed trapezoidal patch dipole antenna for UWB applications has been designed. The proposed antenna exhibits, band-notched characteristics. The antenna covers the entire UWB band ranging from 3.1–10.6 GHz with a gain of 3.1dBi. It has a notched band for the IEEE 802.11a frequency band at 5.825 GHz, which has a gain of 5.1dBi .
From the above literature survey, it is observed that the antenna parameters such as bandwidth, gain, directivity are very low. Several attempts are being made to realize the antenna for Wi-Fi band applications, where the array elements are added either serial formation or parallel formation. Hence the STDA with reflector antenna has considered as the array element and analyzed in 1×4, 1×8 and 2×8 STDA array configurations. High directivity, gain, bandwidth and better Signal-to-noise ratio has been acknowledged with different array configuration. The proposed antenna operates in S-band (2–4 GHz) and is constructed on a 1.6 mm thick FR4 substratum with 4.4 dielectric constant. This antenna has a Wi-Fi functionality. The array antenna is designed and evaluated for S-band applications.
In the previous literature to enhance the bandwidth and gain, the parasitic director with STDA is used. In this attempt, to enhance the gain and bandwidth, the parabolic reflector with STDA is incorporated. The STDA with reflector antenna has considered as the array element and analyzed in 1×4, 1×8 and 2×8 STDA array configurations. High directivity, gain, bandwidth and better Signal-to-noise ratio has been acknowledged with different array configurations.
The minimum gain requirement for wifi system is about 3dBi. A higher-gain antenna, installed for instance on an access point, improves range from the access point to the client radio and from the client radios to the access point. This is different from increasing transmit power on only the access point, which would only increase range for the communications going from the access point to the client radios. The reason is that a higher-gain antenna improves range in both directions. It is identified that the higher gain of the antenna improves both transmission and reception of radio waves. Therefore, the installation of higher-gain antennas can provide significant increases in range without making changes to the client radios. In addition to using higher-gain antennas, antenna diversity can also help extend range in both directions because it minimizes multipath propagation. Diversity is an important part of 802.11n, and various vendors sell 802.11n access points and client radios that have different levels of diversity.
An advantage of using higher-gain antennas is that it impacts range in both directions. As a result, it may be able to get by with changing the antenna configuration on only the access point, avoiding the need to alter each client radio. The cost of upgrading the antennas, however, might be. Therefore, the cost might be prohibitive in larger networks. Be sure to take into account different antenna gain and diversity with actual propagation testing in the target operating environment to determine the lowest overall cost of deploying the network. The trouble with increasing antenna gain for purposes of extending range is that you will likely place the access points farther apart. This results in a larger 802.11 collision domain, which limits the capacity of the WLAN. Finally, in order to enhance the distance, reduce the diversity and cost, the antenna gain is improved through array configurations.
The antenna array is used to increase overall gain, provide diversity of reception, cancel interference, maneuver the array in a particular direction, gage the direction of arrival of incoming signals, and maximize the signal to interference plus noise. Most types of array antennas are constructed using several dipoles, typically half-wave dipoles. The aim of using multiple dipoles is to increase the directional gain of the antenna over the gain of one dipole 
The structure of the paper is as follows; Sect. 2 discusses the geometry and the method to construct the STDA antenna. Array implementation of the STDA is presented in Sect. 3, which is followed by the analysis of the simulated and measured results in Sect. 4. The result and discussion are presented in Sect. 5 and Finally, Sect. 6 concludes the paper.