5G mmWave Band Research Articles

A 26-28 GHz, Two-Stage, Low-Noise Amplifier for Fifth-Generation Radio Frequency and Millimeter-Wave Applications.

This paper presents a high-gain low-noise amplifier (LNA) operating at the 5G mm-wave band. The full design combines two conventional cascode stages: common base (CB) and common emitter (CS). The design technique reduces the miller effect and uses low-voltage supply and low-current-density transistors to simultaneously achieve high gain and low noise figures (NFs). The two-stage LNA topology is analyzed and designed using 0.25 µm SiGe BiCMOS process technology from NXP semiconductors. The measured circuit shows a small signal gain at 26 GHz of 26 dB with a gain error below 1 dB on the entire frequency band (26-28 GHz). The measured average NF is 3.84 dB, demonstrated over the full frequency band under 15 mA current consumption per stage, supplied with a voltage of 3.3 V.

A dual-port, single-fed, integrated microwave and mm-wave MIMO antenna system with parasitic decoupling mechanism for 5G-enabled IoT applications

The integration of microwave and mm-wave antenna is recognized as a promising solution to ensure backward compatibility while effectively utilizing available space for 5G-enabled modern IoT devices. This paper proposed a very compact size multi-band dual-port MIMO antenna module, aiming to provide complete coverage in microwave frequency bands, including 2.4 GHz, 3.5 GHz, 5.3 GHz, and 7.5 GHz, along with 5G mm-wave bands such as 28 GHz. This is achieved through a common feedline by incorporating a semi-circular slotted monopole with strategically positioned quarter-wavelength metallic stubs on a partial ground plane. The proposed antenna exhibited -10 dB impedance bandwidths of 22.6% (2.16–2.71 GHz), 17.9% (3.36–4.02 GHz), 9.4% (5.18–5.69 GHz), 15.9% (7.29–8.55 GHz), and 15.5% (26.02–30.39 GHz) across diverse frequency bands. To attain compactness and high isolation capabilities, a composite three-dimensional parasitic element is employed as a decoupling structure to alleviate significant interference among closely positioned radiating elements. The proposed antenna provides radiation efficiency of > 85%, achieving necessary peak gains of 2.32 dBi, 3.46 dBi, 4.15 dBi, and 5.32 dBi at respective microwave frequencies. While in mm-wave frequency bands, radiation efficiency exceeds 95% having a measured realized gain of 6.2 dBi at 28 GHz. The proposed design successfully maintains an average isolation of > 28 dB in all frequency bands. The suggested MIMO configuration demonstrates outstanding diversity performance, which is evidenced by ECC, DG, MEG, CCL, and TARC.

Joint Microwave and Millimeter-Wave Antenna Design for UAV-Enabled Communications

Wireless communications aided by unmanned aerial vehicles (UAVs) have emerged as a promising technology for serving numerous terminal devices of the Internet of Things (IoT). To support such a broad range of emerging applications, millimeter-wave (mm-Wave) is an effective solution because it has the characteristics of high transmission efficiency, wide frequency band, and very low latency. Meanwhile, a UAV-assisted communication system also requires a global positioning system (GPS) reception (1.575 GHz) and ground control unit (2.4 GHz). This paper investigates a highly integrated multi-band antenna design to operate at the microwave (μ-Wave) and mm-Wave bands for robust and flexible UAV communications. Each antenna operating band utilizes the technology of a substrate-integrated waveguide (SIW) cavity-backed antenna. By strategically engineering an mm-Wave antenna into a 2.4 GHz band antenna to share the aperture, besides showing high aperture reuse efficiency with a large frequency ratio, the proposed antenna has also maintained the geometrical advantages of compactness, planar configuration, and ease of integration with other circuits. Furthermore, the proposed antenna can provide flexible radiation patterns with upper/lower-space signal coverage according to the mission demands of the UAV. Experimental results of the prototype show that the antenna can fully cover the 1.575 GHz, 2.4 GHz, and fifth-generation (5G) mm-Wave bands of n257, n258, and n261. Multiple bands and stable radiation characteristics indicate the proposed antenna's suitability for deploying a UAV-supported wireless network.

Modified U Slot Patch Antenna with Large Frequency Ratio for Vehicle-to-Vehicle Communication

This paper presents a single-fed, single-layer, dual-band antenna with a large frequency ratio of 4.74:1 for vehicle-to-vehicle communication. The antenna consists of a 28 GHz inset-fed rectangular patch embedded into a 5.9 GHz patch antenna for dual-band operation. The designed dual-band antenna operates from 5.81 to 5.99 GHz (Dedicated Short Range Communications, DSRC) and 27.9 to 30.1 GHz (5G millimeter-wave (mm-wave) band). Furthermore, the upper band patch was modified by inserting slots near the inset feed line to achieve an instantaneous bandwidth of 4.5 GHz. The antenna was fabricated and measured. The manufactured prototype operates simultaneously from 5.8 to 6.05 GHz and from 26.8 to 31.3 GHz. Notably, the designed dual-band antenna offers a high peak gain of 7.7 dBi in the DSRC band and 6.38 dBi in the 5G mm-wave band.

A Novel High Isolation 4-Port Compact MIMO Antenna with DGS for 5G Applications.

This paper presents the design and realization of a simple and low-profile, four-port multiple-input-multiple-output (MIMO) antenna operating in a mm-wave band supporting 5G communication technologies. As part of the design methodology, the initial stage involved the development of a conventional monopole patch antenna optimized for operation at 26 GHz, which was matched to a 50 Ω stepped feed line. Afterward, a square-shaped defected ground structure (DGS) with semi-circle slots on the edges was placed on the ground to improve the isolation, and the circular and rectangular slots were incorporated as DGSs to optimize the antenna impedance bandwidth. Etching semi-circular-shaped slots on the ground plane achieved more than 34.2 dB isolation in the 26 GHz operating band. In addition, an arrangement of four symmetrical radiating elements was positioned orthogonally to minimize the antenna's physical size and improve the isolation. The proposed MIMO antenna's overall dimension was 25 × 25 mm2, which was printed on a Rogers 5880 substrate at a width of 0.787 mm and εr = 2.2. The proposed antenna covered the 5G mm-wave band with a 10 dB bandwidth ranging from 25.28-28.02 GHz, whereas the maximum gain attained for the proposed structure was 8.72 dBi. Additionally, the implementation of these slots effectively mitigated mutual coupling, resulting in reduced envelope correlation coefficient (ECC) values. Furthermore, other MIMO performance metrics, including channel capacity loss (CCL), mean effective gain (MEG), and diversity gain (DG), were analyzed for the proposed structure. The obtained results indicate its suitability for various usage areas, such as smart devices, mobile phones, and sensors in 5G applications.

Millimeter-Wave Wide-Angle Scanning Phased Array Antenna Based on Heterogeneous Beam Elements

By imitating the element inclined beam distribution of a curved surface conformal (CSC) phased array antenna (PAA), a pseudo-curved surface conformal (PCSC) PAA realizes wide-angle scanning while maintaining a planar low profile. Inspired by the PCSC PAA, this communication proposes a PAA based on heterogeneous beam elements (HBEs) to realize wide-angle scanning. Using HBEs introduces a new design degree of freedom (DoFs), namely the element beam shape, to PAA. By optimizing HBEs and their arrangement, the effective aperture of a PAA can be increased at large scanning angles, and thus the scanning range can be improved. To verify the idea, first, a wide-beam 1×4-element subarray is developed. Then, a standard 4×4-element PAA is implemented using four uniform 1×4-element subarrays, achieving a >±60° 3-dB gain variation scanning range. At last, based on the standard PAA, by adjusting its structure to tailor four subarrays’ beam inclinations, a 4×4-element HBE PAA is designed. It further improves the scanning range to >±70° at an average cost of ~1.5dBi broadside scanning gain within the 5G mmWave band (24.25-29.5GHz, 19.5%). To the authors’ best knowledge, compared with the former planar mmWave PAAs, the proposed design shows the widest scanning range in a wide bandwidth.

A Wideband GRIN Dielectric Lens Antenna for 5G Applications.

This paper proposes a graded effective refractive indexes (GRIN) dielectric lens for 5G applications. The inhomogeneous holes in the dielectric plate are perforated to provide GRIN in the proposed lens. The constructed lens employs a collection of slabs that correspond to the specified graded effective refractive index. The thickness and the whole lens dimensions are optimized based on designing a compact lens with optimum lens antenna performance (impedance matching bandwidth, gain, 3 dB beamwidth, and sidelobe level). A wideband (WB) microstrip patch antenna is designed to be operated over the entire band of interest from 26 GHz to 30.5 GHz. For the 5G mm-wave band of operation, the behavior of the proposed lens along with a microstrip patch antenna is analyzed at 28 GHz for various performance parameters, including impedance matching bandwidth, 3 dB beamwidth, maximum gain, and sidelobe level. It has been observed that the antenna exhibits good performance over the entire band of interest in terms of gain, 3 dB beamwidth, and sidelobe level. The numerical simulation results are validated using two different simulation solvers. The proposed unique and innovative configuration is well-suited for 5G high gain antenna solutions with a low-cost and lightweight antenna structure.

Wideband High-Gain Low-Profile Endfire Linearly/Circularly Polarized Antennas Based on Magnetic Dipole Directors for Millimeter-Wave Applications

Wideband high-gain low-profile endfire linearly polarized (LP)/circularly polarized (CP) antennas for 5G millimeter-wave (mmWave) applications are presented in this letter. The basic structure of the antennas include a stripline fed horn as the feeder and multiple magnetic diploe directors (MDDs) printed on a single layer substrate. The stripline fed horn exhibits a wide bandwidth and stable endfire radiation, and magnetic dipole directors help further improvement the endfire gain. A LP antenna based on a LP feeder and vertically polarized (VP) MDDs (supporting VP resonance) working at the 5G mmWave band is first designed. Then, on this basis, CP antenna based on a CP feeder and dual-polarized MDDs (supporting two orthogonal polarized resonances) working at the same band is designed. The two proposed antennas with the low profile of 0.14λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> are fabricated and measured, both of which show good impedance matching, high gain, and low cross polarization within the 5G mmWave band.

Millimeter-Wave 1-D Wide-Angle Scanning Pseudo-Curved Surface Conformal Phased Array Antennas Based on Elongated Planar Aperture Element

To perform wide-angle scanning while maintaining a planar low profile, we propose a new kind of millimeter-wave (mmWave) planar phased array antenna using inclined beam elements to imitate a curved surface conformal (CSC) array, called a pseudo-curved surface conformal (PCSC) phased array antenna. We present the concept of our PCSC phased array and then design an elongated planar aperture antenna (EPAA) element, achieving stable high broadside gain and wide beam on the scanning plane within a wide bandwidth. Then, by introducing asymmetries to the EPAA element, the beam inclination of the EPAA element can be adjusted. Accordingly, we use EPAA elements with different beam inclinations to form a 1 × 4-element 1-D wide-angle scanning PCSC phased array antenna. We design, fabricate, and measure a prototype of our proposal, with measured results showing that the proposed design has a 3 dB gain variation across a scanning range of more than ±62° (and as high as ±68°) within the 5G mmWave band (24.25 to 29.5 GHz), which is about ±10° better than its traditional counterpart.

Design of a Low-Profile Dual Linearly Polarized Antenna Array for mm-Wave 5G

This work proposes a dual linearly polarized antenna array for 5G mm-wave band, which is designed to be compatible with planar printed circuit board technology. The proposed antenna is engineered with a focus on simplifying the antenna geometry and eliminating any critical issues that may arise in antenna manufacturing. The proposed antenna has been evaluated, finding a 7% impedance bandwidth centered around 27.28 GHz. Additionally, the beam steering capability of the antenna is found to cover a ±30% angular width for both linear polarizations. These findings highlight the potential of the proposed antenna for use in 5G mm-wave band applications, where compatibility with planar printed circuit board technology and simplified antenna geometry are essential design requirements.

Multifunctional Frequency Selective Absorber Enabling FR1 and FR2 5G OTA Tests in a Hybrid Reverberation Chamber

Due to the special advantages of the reverberation chamber (RC), it has been recognized as a standardized over-the-air (OTA) testing methodology by the cellular telecommunications industry association (CTIA). Currently, OTA tests of the fifth-generation (5G) wireless terminals are usually performed in different testing environments, e.g., in a reverberation chamber for fast isotropic tests in the sub-6 GHz frequency band, and in an anechoic chamber for directional tests in the millimeter-wave (mm-wave) frequency band, which are inconvenient and costly. In this work, two multi-functional frequency selective absorbers (FSAs) are designed to realize absorption in the 5G mm-wave band and reflection/transmission in the sub-6 GHz band. By loading the FSAs to the RC, an integrated testing environment for 5G terminals can be established. Namely, a quasi-anechoic environment in the mm-wave band and a reverberation environment in the sub-6 GHz band can be simultaneously achieved in the RC loaded with the proposed FSAs. Experimental and simulated results are presented to demonstrate the effectiveness of the proposed scheme.

Communication Compact Dual-Band Hybrid Dielectric Resonator Antenna for 5G Millimeter-Wave Applications

In this communication, a new kind of dual-band hybrid dielectric resonator antenna (DRA) with its array design and extended dual-polarized version is presented for fifth generation (5G) millimeter-wave (mm-Wave) applications. The hybrid antenna that integrates three types of resonators of strip, slot, and DRA can generate four resonances in 28 and 39 GHz frequency bands. In this design, the strip and slot modes are used to cover the lower frequency band of 26.41–30.42 GHz, while the TE111 and TE131 modes of the DRA are employed to cover the upper frequency band of 36.05–40.88 GHz. It shows that the 5G mm-Wave bands of n257 and n260 can be covered simultaneously. It should be mentioned that our proposed hybrid antenna has a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.34\lambda _{01} \times 0.36\lambda _{01} \times 0.1\lambda _{01}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{01}$ </tex-math></inline-formula> means the free-space wavelength at 28 GHz). Based on the compact size of the antenna element, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 \times $ </tex-math></inline-formula> 5 antenna array with the capability of beam steering is designed and simulated. Wide steering angles of ±50° and ±40° can be obtained at 28 and 39 GHz frequency bands, respectively. Furthermore, an extended dual-polarized antenna configuration is also described and measured that provides similar two-port impedance and radiation performance with the single-port counterpart.

Design and Analysis of Microstrip Rectangular Patch Antenna for 5G Applications

The rectangular Microstrip patch antenna is a popular choice for 5G applications due to its integrated design and wideband capabilities. Operating in the 1 GHz to 3 GHz range, this antenna boasts a gain of 4 dBi. In a recent study, researchers utilized the 5G mm-wave bands at a resonance frequency of 39 GHz to create a high-definition video antenna for various 5G applications. The proposed design incorporates a dielectric constant of 4.4 and was analyzed and simulated using HFSS software. Results from the simulation demonstrated a good bandwidth of 3.5 GHz, return loss of -31.87 dB, and a voltage standing wave ratio (VSWR) of 1.

Dielectric Metasurface Inspired Directional Multi-Port Luneburg Lens as a Medium for 5G Wireless Power Transfer—A Design Methodology

In this paper, a novel dielectric metasurface-inspired multi-beam directional Luneburg lens is proposed as a wireless power transfer medium at 5G mm-wave band. The lens is constructed using dielectric-based unit cells made up of a glide symmetric approach. It is connected with a set of microwave detector integrated multi-port tapered rectangular feeds to convert the received RF energy from different directions to DC power across a combined load. The proposed structure can be a potential candidate to harvest ambient energy from a wide coverage range of around 160° and produce a power conversion efficiency of about 76% for an input power of 14.9 dBm at 24 GHz.

Frequency Integration of Dual-band Hexagonal Metamaterial Resonator antenna for Wi-Fi and 5G Wireless Communication

Abstract The integration of 5G mm-wave and Wi-Fi frequency bands becomes significant for upcoming 5G wireless applications for providing a large frequency ratio. This work presents a frequency reconfigurable hexagonal metamaterial resonator (HMR) antenna for Wi-Fi and a 5G mm-wave frequency band. A PIN diode is utilized to link up a microstrip patch antenna (MPA) with HMR to achieve integration of the Wi-Fi frequency band. The resonant frequency of the proposed antenna is 5 GHz (Wi-Fi) and 27.87 GHz with peak gain 2.33 dB and 7.12 dB, respectively. The operating bandwidth of the proposed antenna is 800 MHz (4.5-5.3 GHz) and 1020 MHz (27.35-28.37 GHz). The rogers RT5880 substrate with thickness 0.508 mm, dielectric constant 2.2, and loss tangent 0.009 has been used for designing the antenna. The overall size of the antenna is 30×23×0.508 mm3.

High-Isolation MIMO Antenna for 5G Millimeter-Wave Communication Systems

The work in this article presents the design and realization of a low-profile, four-port MIMO antenna supporting fifth-generation (5G) wireless applications operating at a millimeter-Wave (mm-Wave) band. Each MIMO antenna is a 2-element array fed with a corporate feeding network, whereas the single antenna is a patch with a bow-tie slot at the center and slits at the edges. The vertical and horizontal slots are incorporated as a Defected Ground Structure (DGS) to optimize the antenna performance. In addition, a slotted zig-zag decoupling structure is etched from edge to edge on the top side to enhance the isolation. Significant isolation (&gt;−40 dB) is achieved between antenna elements by employing spatial and polarization diversity techniques. The proposed antenna covers the 5G mm-Wave band with a −10 dB bandwidth ranging from 27.6–28.6 GHz, whereas the maximum gain attained for the proposed structure is 12.02 dBi. Moreover, the lower correlation values, higher diversity gain, and lower channel capacity loss make it a suitable contender for 5G MIMO applications at the mm-Wave range.

Design Challenges and Possible Solutions for 5G SIW MIMO and Phased Array Antennas: A Review

With the increasing demand for high-speed data, rapid deployments of the 5G terrestrial heterogeneous wireless networks are expected worldwide in the next decade. In such networks, sub-6 GHz macro-cells overlapped by mmWave small-cells are being used to cater to densely populated regions. As a result, several challenges arise with the antenna design technologies used at the mobile terminal, access points, or backhaul/front haul levels. These challenges are being addressed using multiple-input multiple-output (MIMO), massive-MIMO, and phased array antenna technologies. In order to implement these antenna technologies, considering the expanding 5G scenario, substrate integrated waveguide (SIW) offers a viable solution due to its low-cost, low-profile, high-power handling, low transmission loss, and ease of integration with the radio circuits; therefore, the SIW plays a vital role in developing the modern radio systems. The proposed study aimed to provide a comprehensive overview of SIW MIMO and phased array antennas operating in the 5G sub-6 GHz and mmWave bands. It deliberates the specific issues related to the band of operations and challenges in designing different antenna structures. After careful investigation and detailed analysis, this paper identified existing research gaps and suggested possible antenna design solutions for prospective researchers who intend to explore further the aforementioned promising area and present future research directions.

Differential-Fed, Dual-Aperture Based, Quasi-End-Fire 5G mmWave Antenna-in-Package Design

A low-profile, wideband antenna-in-package (AiP) design is proposed for 5G mmWave mobile applications. The aperture-coupled feeding incorporated with the microstrip feed line through the slots in the ground is used to excite the patch antenna. Firstly, a thin quarter-wave shorted patch antenna (QW-SPA) with the dominant <i>TM</i>^<i>z</i>_1/2,0,0 mode is realized. To broaden the operating band, the QW-SPA is extended along its resonant length so that the <i>TM</i>^<i>z</i>_1,0,0 mode can also be excited. The offset introduced into the two slots together with the additional shorting via wall are applied to enhance the beam tilt toward the end-fire direction. The proposed single-patch design shows a wide fractional bandwidth, covering the 5G mmWave band n257 (26.5&#x2013;29.5 GHz). Furthermore, to increase more beam tilt, the differential-fed, two-patch sub-array formed by two QW-SPAs spaced a half-wavelength at 28 GHz apart is also presented. Compared with the single-patch design, the beam-tilt enhancement of around 10&#x2013;27 degrees is obtained over the desired frequency band with the peak gain of around 8.2 dBi for the sub-array AiP design.

Performance of SVM technique for DoA Estimation in 5G mm-Wave band

Applying Machine Learning algorithms in wireless communication has shown increasing interest due to the increase of demand on capacity, the increase of the number of users, and equipment sharing the limited frequency spectrum resources. Also, the need for a reduction in power consumption at base stations and the optimization of radio coverage make ML an attractive and promising technique. In this paper, we investigate the usage of Support Vector Machine (SVM) technique for Direction of Arrival (DoA) estimation in the millimeter-wave band. The objective is to predict the location of a user in a given area by analyzing the received signals at an array of antennas, using an SVM-based model. The first phase of this technique consists of the training phase that aims to identify the characteristics of each class, and that is based on a set of training samples. The second phase consists of testing the trained model using a set of samples/users. We have carried out a set of simulations based on the developed model. The results are promising in terms of the accuracy of determining the DoA, taking into consideration a channel with noise and multipath.

A low‐profile and wide‐beam circularly polarized microstrip antenna with resonant structure based on 3/4 λ phase‐shifted sequential rotating feed technology

A novel single-layer coplanar-fed circularly polarized (CP) microstrip antenna is proposed in this article. In order to improve the CP performance, a new sequential rotating feed network based on 3/4 λ (where λ is the wavelength in the medium) phase shift line is adopted in the antenna design, which is on the same plane as the radiating patch to achieve low-profile characteristics. A curved microstrip resonant structure is loaded around the radiating patch, the half-power beam width (HPBW) of the antenna is obviously widened. Meanwhile the height is only 0.06 λ0, thus low profile and wide-beam characteristics are achieved. In order to prove the effectiveness of the design method, a prototype is fabricated and measured. The measurement results show that it has good impedance matching (from 24.7 to 27.6 GHz) in the 5G mmWave bands. Within the operating bandwidth of the antenna, the HPBW of antenna can reach 125° in xoz-plane and 110° in yoz-plane. This design method can suitable for 5G mobile communication systems in future.