The intensive research in the fifth generation (5G) technology is a clear indication of technological revolution to meet the ever-increasing demand and needs for high speed communication as well as Internet of Thing (IoT) based applications. The timely upgradation in 5G technology standards is released by third generation partnership project (3GPP) which enables the researchers to refine the research objectives and contribute towards the development. The 5G technology will be supported by not only smartphones but also different IoT devices to provide different services like smart building, smart city, and many more which will require a 5G antenna with low latency, low path loss, and stable radiation pattern. This paper provides a comprehensive study of different antenna designs considering various 5G antenna design aspects like compactness, efficiency, isolation, etc. This review paper elaborates the state-of-the-art research on the different types of antennas with their performance enhancement techniques for 5G technology in recent years. Also, this paper precisely covers 5G specifications and categorization of antennas followed by a comparative analysis of different antenna designs. Till now, many 5G antenna designs have been proposed by the different researchers, but an exhaustive review of different types of 5G antenna with their performance enhancement method is not yet done. So, in this paper, we have attempted to explore the different types of 5G antenna designs, their performance enhancement techniques, comparison, and future breakthroughs in a holistic way.

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Fifth Generation Antennas: A Comprehensive Review of Design and Performance Enhancement Techniques

A novel ultra-wideband (UWB) multiple-input multiple-output (MIMO) Vivaldi antenna with dual band-notched characteristics is presented and fabricated. The antenna is comprised of an improved ground plane and two microstrip feeding lines with a compact size of $26\times 26$ mm
 2
. The evolutionary process of the antenna is given. By etching the T-shaped slot on the ground plane, the port isolation between individual antenna elements can be greatly increased. Meanwhile, by adding two split ring resonator (SRR) of different sizes next to the microstrip feed lines, dual notches can be achieved to filter the interfere of WLAN and X-band communication satellites. The notched mechanism is analyzed from the surface current distributions. The experimental results show that the impedance bandwidth of the designed MIMO antenna is from 2.9 to 11.6 GHz, along with two notched bands covering 5.3-5.8 GHz and 7.85-8.55 GHz, and the mutual coupling is less than -16 dB in the whole working bandwidth. The MIMO antenna has good radiation characteristics, stable gain, and very low envelop correlation coefficient (ECC <;0.02), which is suitable for UWB MIMO system applications. The idea in this paper also has a certain guiding significance for the study of band-notched MIMO Vivaldi antenna.

/pdf/compact-uwb-mimo-vivaldi-antenna-with-dual-band-notched-4uuurpnat8.pdf

Compact UWB MIMO Vivaldi Antenna With Dual Band-Notched Characteristics

A structure of a compact ultra-wideband monopole antenna has been presented. The antenna consists of a microstrip-fed rectangle radiator as well as a ground plane with a rectangle slit and an L-shaped stub. The critical factor in achieving a small size is a careful design procedure involving numerical optimisation of all geometry parameters of the antenna aiming at explicit size reduction while maintaining acceptable electrical performance. The final design exhibits dimensions of only 9.45 × 18.5 mm and a footprint of 175 mm
 2
. Experimental validation and comparisons with competitive designs are also provided.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2015.4432

Compact UWB monopole antenna for internet of things applications

A novel coplanar waveguide-fed transparent antenna for ultrawideband applications with enhanced bandwidth is presented. In this design, different techniques have been used to broaden the bandwidth. The rectangular radiator of the antenna is equipped by the staircase technique to increase the overlapped resonant frequencies. Moreover, two major and minor symmetrical rectangular stubs are mounted on top of the quarter-circle slot ground by using a dual axis to significantly increase the bandwidth between 3.15 and 32 GHz for VSWR <; 2. AghT-8 transparent thin film is used in the design of the proposed antenna to obtain a very compact size and lightweight structure.

CPW-Fed Transparent Antenna for Extended Ultrawideband Applications

A very small coplanar waveguide (CPW)-fed rectangular slot antenna with dual band-notched characteristics for super ultrawideband (UWB) applications is proposed. This antenna consists of a rectangular slot, a beveled rectangular patch, two S-shaped slits cut in the ground plane and an elliptical ring slot (ERS) etched in the patch. The corners of a simple rectangular patch are beveled to improve the impedance bandwidth, especially at the middle frequencies of the band. In addition, a pair of semicircle slots is etched in the ground plane to enhance the bandwidth to more than 23 GHz. A pair of S-shaped slits connected to the rectangular slot, and an ERS cut in the beveled rectangular patch, is employed to create band-notched performances in WiMAX and WLAN spectrum, respectively. The proposed antenna has a very small size of $15 \times 15 \text{mm}^{2}$ , and therefore, it is one of the smallest UWB slot antennas that have been reported until now, and provide a very wide impedance bandwidth from 2.6 to more than 23 GHz for $\text{VSWR} with dual band-notched properties.

Very Small Dual Band-Notched Rectangular Slot Antenna With Enhanced Impedance Bandwidth

A novel coplanar waveguide (CPW)-fed compact ultrawideband (UWB) microstrip antenna is proposed for ultrawideband applications. The proposed antenna posseses a method to minimize the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of $25 \times 25 \times 1.6\ {\hbox{mm}}^3$ achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6-13.04 GHz (10.44 GHz).

A CPW-Fed Compact UWB Microstrip Antenna

This study describes the design of a very compact dual-band-notched ultrawide band (UWB) multiple-input multiple-output (MIMO) antenna. The main features of the proposed antenna are its compact dimensions and high isolation between the two antenna elements. The UWB performance of the antenna is attained by designing two identical triangular-shaped patch elements, which are designed opposite to each other and connected to a tapered microstrip feedline. The ground plane of the proposed antenna consists of a funnel-shaped patch connected with two triangles at the lower end. In addition, two J-shaped slits are etched in the radiator to get the band rejection characteristics at wireless local area network band from 5.1 to 5.8 GHz and IEEE INSAT/Super-Extended C-band from 6.7 to 7.1 GHz. The designed antenna has the smallest dimension of 
. Results show that the MIMO antenna has a large impedance bandwidth of 31.9 GHz from 3.1 to 35 GHz. The diversity performance of the proposed antenna is also analysed using different parameters such as envelope correlation coefficient (ECC), diversity gain, total active reflection coefficient and so on. Due to the low mutual coupling of <−24 dB and ECC of <0.2 across the frequency band this antenna is a good candidate for portable UWB applications.

Design of ultra-compact UWB antenna with band-notched characteristics for MIMO applications

A novel CPW-fed compact inverted L-strip ultra wideband (UWB) microstrip antenna is proposed for ultra wide band applications. The proposed antenna possesses a method to minimize the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of 25 × 25× 1.6 mm3 achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6–13.04 GHz (10.44 GHz). © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1584–1589, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27651

A CPW‐FED compact inverted L‐strip UWB microstrip antenna

A compact circular waveguide polarizer with higher order input mode (TM01) is presented in this paper. The proposed design consists of a triangular metallic plate for TM01-TE11 (linearly polarized) mode conversion and metallic posts loading for linear TE11 to Circular TE11 polarization conversion. The structure is simulated in CST Microwave Studio. Axial ratio is below 3dB and conversion efficiency is above 90% over a bandwidth of 3.28-3.72 GHz. The relative bandwidth is 12.9% (440 MHz) at the operating frequency of 3.4 GHz. The design is purely metallic and calculated high power microwave capability is upto 146 MW. The compact size, light weight structure, high efficiency and high power capability of the polarizer makes it suitable for airborne and portable High Power Microwave (HPM) systems and Space applications.

A Compact Circular Waveguide Polarizer with Higher Order Mode Excitation

A high power Ultra-wideband Transverse Electromagnetic Mode (TEM) horn antenna with a compact and light-weight structure is presented in this paper. The proposed antenna is designed for 3.1-13 GHz. The simulated reflection coefficient (S11) is below -10 dB over the entire wide band. It has a high gain up to 12.5 dBi. This antenna can handle a high power microwave signal in MW without electrical breakdown. It is compact and light-weight. Therefore, it can be suitable for portable and airborne high power microwave systems.

Swati Yadav

Papers

A CPW-Fed Compact UWB Microstrip Antenna

Design of ultra-compact UWB antenna with band-notched characteristics for MIMO applications

A CPW‐FED compact inverted L‐strip UWB microstrip antenna

A Compact Circular Waveguide Polarizer with Higher Order Mode Excitation

A Compact high Power UWB TEM Horn Antenna