Advanced Antenna Research Articles

Time Averaged Power Control of a 4G or a 5G Radio Base Station for RF EMF Compliance

Currently, high gain antenna arrays are deployed in cellular radio systems to enhance wireless capacity. These advanced antenna systems increase the peak equivalent isotropic radiated powers (EIRPs), thereby potentially also increasing the size of the exclusion zones for radio frequency (RF) electro magnetic field (EMF) exposure that are applied to limit the presence of workers and the general public in the vicinity of the antennas. The exclusion zones are determined from the RF EMF exposure limits, typically expressed in terms of time-averaged incident power density values as provided by national authorities and regulatory bodies. To mitigate possible deployment challenges in some urban areas due to the overly conservative use of peak EIRP in determining exclusion zones, the possibility of basing the exclusion zone on a time averaged EIRP is discussed. To support this new approach, this paper presents an average power feedback controller that mathematically guarantees that the average power transmitted over a specified time window by a single radio base station stays below a determined value defining the exclusion zone. Such automation may be required by regulators to allow the use of time averaged quantities for RF EMF exposure assessment and exclusion zone determination. The developed average power controller uses a combination of controllers to regulate the rate of change of a momentary fractional frequency resource limit in the scheduler. This restricts the momentary total transmit power since the transmit power is proportional to the scheduled frequency resources. Simulation results, laboratory measurements and on-site measurements for a commercially available 5G MIMO transmitting base station are then reported, all of them verifying that the average power controller performs as intended. The average power control solution is applicable for any 4G or 5G base station, with or without MIMO transmission capability.

Compact flexible inkjet-printing antenna on paper and transparent PET substrate materials for vehicular instrument communication

Flexible inkjet-printed antenna models are designed on paper and transparent polyethylene terephthalate substrate material for vehicular instrument communication applications. The antenna model 1 is designed initially on a low-cost photo paper substrate material and later model 2 is designed on flexible PET substrate for vehicular instrument communication with dimensions of 40×38.5×0.2 mm3. The proposed antenna model on PET substrate is providing the excellent bandwidth of 7.6 GHz with impedance bandwidth of 78%. The proposed antenna is designed to operate in vehicular communication bands, which includes the cellular communication bands, V2X communication bands and other wireless applications like Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE2600), Wireless local area network 2.4 GHz (WLAN), World Interoperability for Microwave Access (WiMAX), IEEE802.11p protocol based Vehicle-to-everything 5.8 GHz, Dedicated short-range communications (DSRC) and Wireless Access in Vehicular Environments 5GHz (WAVE) communications bands. The prototyped models are fabricated and tested for validation and found perfect matching with the simulation results with respect to reflection coefficient, radiation patterns and gain. The achieved results based on the proposed techniques can be extended for other flexible substrates to design complex advanced antennas and communication modules.

SLL attenuation-based thinned antenna design for next-generation communications

Among the hot issues of the Fifth Generation (5G), developing by the Third Generation Partnership Project (3GPP), advanced antenna design significantly improves the wireless communication qualities. However, limited number of researches have been published on how the smarter antenna design satisfies the 5G antenna design requirements. Hence, in this paper, we have shown that effective antenna designing techniques achieve substantial antenna performance enhancements that are essential input for the current and next-generation communication engineering. First, the excitation weights of the individual array elements are optimized to obtain enhanced antenna performances including reduced side lobe level (SLL), high directivity, reduced power consumption, and flexible radiation pattern. Then, a novel SLL attenuation technique is introduced to further reduce the SLL, power wastage, and interference. In general, the proposed technique of radiation pattern synthesis has resulted in to much better SLL reduction, directivity improvement, power wastage and interference reduction.

5G New Radio: Unveiling the Essentials of the Next Generation Wireless Access Technology

The fifth generation (5G) wireless access technology, known as New Radio (NR), will address a variety of usage scenarios from enhanced mobile broadband to ultra-reliable low-latency communications to massive machine type communications. Key technology features include ultra-lean transmission, support for low latency, advanced antenna technologies, and spectrum flexibility including operation in high frequency bands and inter-working between high and low frequency bands. This article provides an overview of the essentials of the state of the art in 5G wireless technology represented by the 3GPP NR technical specifications, with a focus on the physical layer. We describe the fundamental concepts of 5G NR, explain in detail the design of physical channels and reference signals, and share the various design rationales influencing standardization.

Precisely manipulated origami for consecutive frequency reconfigurable antennas

Shape and function reconfigurable materials and structures are widely explored for their unique merits. Since wireless communication devices are critical in cutting-edge communication systems, multi-function antennas with reconfigurable capability are highly pursued to meet the requirements of operating under different situations. To address critical problems in the currently explored reconfigurable origami antenna, including antenna durability, performance and structure stability, inaccurate manipulation, insufficient tunable bandwidths, here a novel type of frequency reconfigurable origami antenna is developed coupled with a precisely manipulatable mechanism, followed by manipulation with shape memory alloy springs. By integrating the dipole antenna components, the as-manufactured origami antennas are expected to present continuous frequency reconfiguration capability in the frequency range of 0.95–1.6 GHz, implying a relative broadened tunable operating frequency of 75%. According to the simulated and experimental results, combination of origami antenna design, precise manipulation technology and multi-material 3D printing collectively promises a simple and rapid strategy for achieving advanced continuous frequency reconfigurable antennas, which hold more durable and stable ability in both antenna structures and operating performance.

Leaky-Wave Radiations with Arbitrarily Customizable Polarizations Based on Spoof Surface Plasmon Polaritons

Leaky-wave antennas (LWAs), which exploit traveling waves with phase velocity greater than the speed of light, have attracted much attention for their miniaturizability and easy fabrication. However, the polarization states of leaky-wave radiation are generally hard to design at will. This study presents a spoof-surface-plasmon waveguide with bilateral tilted grooves to tailor the polarization of its emission. The design is simple and feasible for realizing arbitrary polarization of leaky waves, just by changing the relative displacement of grooves on either side of the waveguide, and is expected to impact advanced microwave circuits and antennas.

A Survey of Underwater Magnetic Induction Communications: Fundamental Issues, Recent Advances, and Challenges

Enabling underwater wireless communications to conveniently interconnect various underwater deployed devices for data transmission, information sharing, and networking is among the most crucial issues in marine information networks. Apart from the conventional acoustic, optical, and electromagnetic techniques, the magnetic induction (MI) communication, as a promising alternative, has drawn significant attentions recently due to its inherent advantages in predictable channel responses, negligible propagation delay, and competitive energy consumption. In this paper, we attempt to provide a comprehensive and in-depth survey of the existing research on underwater MI communications, classified as the four topics of channel modeling, reliability guarantee, range extension, and capacity enhancement, and present the state-of-the-art advances on each topic. Specifically, the approaches for channel modeling of underwater MI communications, including proposed channel models and involved basic theories, are first summarized. Then, the existing works on reliability guarantee are expounded following the evolution of antenna design from traditional single-directional to advanced multi-directional MI antennas. Furthermore, as to range extension, two typical categories of MI relaying techniques, i.e., the MI waveguide and the active relaying techniques, are reviewed in detail. In particular, the potential of a hybrid relay transmission scheme proposed by us through flexible combination of these two techniques in achieving both energy-efficient and long-range underwater transmission is also addressed in this part. Finally, the existing approaches on extending or reusing the available frequency bands to enhance the underwater MI channel capacity are elaborated. Challenges and open issues that need to be further investigated related to each of the four topics are also profoundly discussed and analyzed in each part.

A Comparison Between Measured and Computed Assessments of the RF Exposure Compliance Boundary of an In-Situ Radio Base Station Massive MIMO Antenna

Advanced antenna technology in the form of massive multiple input multiple output (mMIMO) antennas has been deployed in fourth generation (4G) long term evolution (LTE) mobile networks and will be a standard feature in fifth generation (5G) networks. A characteristic of mMIMO is beamforming in which a large array of antenna elements is used to concentrate energy in specific narrow directions to improve data throughput. Assessing the electromagnetic field (EMF) compliance boundary around a beamforming capable mMIMO antenna using a traditional approach that assumes maximum power is simultaneously transmitted in every possible direction and the radio base station (RBS) is fully loaded (100% traffic utilization) may produce very conservative results. In this study we report on measurements of the 6-minute time-averaged EMF levels in front of a mMIMO antenna operating in a 4G LTE time division duplex (TDD) network and compare results with conservatively computed EMF levels. The RBS serves users scattered throughout a dense urban environment characterized by low rise commercial/industrial buildings. When scaled to 100% RBS traffic loading and taking TDD operation into account, the highest measured EMF level was 7.3% to 16.1% of the ICNIRP occupational reference level compared to a conservative computed level of 79.3%. This represents a far-field reduction in the occupational compliance boundary of between 2.2 and 3.3 times and is consistent with other statistically based theoretical studies. An additional reduction in the compliance boundary can be expected due to actual RBS traffic loading often being much less than 100%.

Метод проектування радіолокаційних станцій наземної розвідки з антенною системою колової поляризації

Radar stations of ground intelligence of mobile targets such as PSD-5 Credo, PSNR-8 Credo-M1 receives and emit only waves of linear polarization. The article deals with the method of designing ground-based ground-based intelligence stations for moving targets by using methods for determining the electromagnetic field scattered by a horn luminaire of linear polarization with their subsequent adaptation to antenna systems with circular polarization. The results of researches should be used in designing new, more advanced antenna systems of radar stations with improved polarization characteristics. The introduction of such antennas will improve the quality of detection of targets against the backdrop of passive and active damage to existing and prospective ground-based intelligence stations. It is proposed to replace state antennas of ground-based radar stations receiving only a linearly polarized wave on an antenna system with circular polarization, the simulation process of which is greatly simplified when applying the proposed method.

Guest Editorial Special Cluster on Three-Dimensional Printed Antennas and Electromagnetic Structures

The papers in this special section examine current research involving 3-D printing technology for advanced and novel antenna applications and electromagnetic structures.

The Compliance to Broadcast Standards of a Side-Mounted Circularly Polarized Antenna

Non-directional antenna bays in FM broadcast applications were designed to exhibit radiation characteristics that conform to broadcast standards. However, the metallic tower where these antennas are mounted and secured is not considered during the development process. Knowing that the radiation characteristics of antennas are affected by the metallic tower, it is the aim of this paper to present the compliance of the side-mounted Circularly Polarized Antenna (CPA) to broadcast standards. The CPA compliance to requirements on polarization components, pattern circularity and bandwidth is specifically presented. Results of numerical analyses using an advanced antenna simulation software show that the radiation characteristics of the CPA are severely altered by the presence of the tower and thus impairing its capacity to adhere to the said broadcast requirements. Some adjustments on the CPA structure are needed to improve its performance.

Topology Optimization of Dual Octagonal Array antenna for low frequency applications

Objectives: Efficient antenna design for use in communication systems is altering the face of the antenna modeling. The ever-increasing demand for portable and efficient antennas is making researchers to develop innovative models [1] using advanced antenna modeling tools that comply with industrial needs and standards. Methods/Statistical Analysis: Antennas with lower operating frequencies have the major constraints on its size, efficiency and gain. Study on matching techniques, feeding techniques was also to be considered.Findings: Micro strip patch antennas offers considerable amount of radiation, low cost when fabricated on FR4, light weight and are conformable to suite any application. This paper projects the design, simulation and testing of a dual octagonal patch, the topology algorithm [3] is used to optimize the size and shape of the patch where octagons are spaced in the form of an array to address optimization on size and fits into wireless applications. Application/Improvements: The proposed model is tested in the standard antenna test bench comprising of microwave integrated circuit analyzer receiver MIC10kit and found to operate at a resonant frequency of 1.8 GHz with good radiation characteristics.

Wideband and high gain antenna arrays for UAV‐to‐UAV and UAV‐to‐ground communication in flying ad‐hoc networks (FANETs)

AbstractA directional 1 × 2 and 2 × 2 microstrip patch antenna array is proposed for UAV‐to‐UAV and UAV‐to‐ground communication in next generation flying ad‐hoc networks (FANETs). The antenna arrays resonate in the 5 GHz frequency band. These antennas were designed and simulated using Agilent ADS Momentum using Rogers RT/Duroid 5880LZ substrate (ɛr = 1.96 and h = 2.54 mm). A hybrid feed technique is used for the antenna arrays with a quarter‐wave transformer‐based network to match the impedance from the feed‐point to the antenna to 50 Ω. The antenna is optimized to achieve directional radiation pattern by introducing two symmetrical slots at the non‐radiating edges of the patch. The gain achieved for the single‐element antenna, 1 × 2 and 2 × 2 antenna arrays are 7.5 dBi, 9.4 dBi, and 10.8 dBi, respectively, which are ideal for FANET applications to perform communication between the swarms of quad‐rotor copter (QRC) type UAVs. The antenna array design is less complex and can be used for the advanced antenna beam‐steering systems in next generation FANETs.

Channel Estimation for Millimeter-Wave MIMO Communications With Lens Antenna Arrays

Millimeter-wave (mmWave) communication is a promising technology for future wireless communication systems. By utilizing the advanced lens antenna arrays, a mmWave lens multiple-input multiple-output (MIMO) system significantly reduces the number of radio-frequency (RF) chains required, and thus, achieves cost-effective implementation. In this paper, we propose a novel channel estimation scheme for the mmWave lens MIMO system with limited RF chains. The proposed scheme is applicable for the general mmWave MIMO communications, regardless of narrow-band or wide-band, time-division-duplexing or frequency-division-duplexing operations. By exploiting the energy-focusing property of lens arrays, jointly with the multipath sparsity of mmWave channels, the proposed channel estimation scheme requires only low-complexity two-way energy-based antenna selections and reduced-size MIMO channel estimation. Numerical results show that under limited RF chains and taking the channel training overhead and imperfect estimation into account, the proposed lens MIMO system achieves significantly higher throughput compared to the more complex benchmark system with the conventional uniform planar array and MIMO-orthogonal-frequency-division-multiplexing-based transmissions.

Advanced Antennas for Small Satellites

Antenna is one of the key components onboard small satellites as its design determines the performance of all the wireless systems including telemetry, tracking and control, high-speed data downlink, navigation, intersatellite communications, intrasatellite communications, wireless power transfer, radars and sensors, etc. This paper presents a review of recent development in advanced antennas for small satellites (MiniSat, MicroSat, NanoSat, CubeSat, etc.). A number of recent examples of antennas for small satellite applications are shown and discussed. A conclusion and future development in antennas for small satellites are given in the end.

Uplink Channel Estimation and Data Transmission in Millimeter-Wave CRAN With Lens Antenna Arrays

Millimeter-wave (mmWave) communication and network densification hold great promise for achieving high-rate communication in next-generation wireless networks. Cloud radio access network (CRAN), in which low-complexity remote radio heads (RRHs) coordinated by a central unit (CU) are deployed to serve users in a distributed manner, is a cost-effective solution to achieve network densification. However, when operating over a large bandwidth in the mmWave frequencies, the digital fronthaul links in a CRAN would be easily saturated by the large amount of sampled and quantized signals to be transferred between RRHs and the CU. To tackle this challenge, we propose in this paper a new architecture for mmWave-based CRAN with advanced lens antenna arrays at the RRHs. Due to the energy focusing property, lens antenna arrays are effective in exploiting the angular sparsity of mmWave channels, and thus help in substantially reducing the fronthaul rate and simplifying the signal processing at the multi-antenna RRHs and the CU, even when the channels are frequency-selective. We consider the uplink transmission in a mmWave CRAN with lens antenna arrays and propose a low-complexity quantization bit allocation scheme for multiple antennas at each RRH to meet the given fronthaul rate constraint. Further, we propose a channel estimation technique that exploits the energy focusing property of the lens array and can be implemented at the CU with low complexity. Finally, we compare the proposed mmWave CRAN using lens antenna arrays with a conventional CRAN using uniform planar arrays at the RRHs, and show that the proposed design achieves significant throughput gains, yet with much lower complexity.

Review on low-cost wireless communication systems for slope stability monitoring in opencast mines

Slope stability is one of the primary problems faced by opencast mines. The conventional geotechnical sensors are monitored by technicians in the field and the available wireless monitoring systems like slope stability radar (SSR), light detection and ranging (LiDAR) are more expensive. Critical observations on recent low-cost wireless slope monitoring systems were presented. By deploying the wireless data transmission system using advanced antennas at respective slope instruments in underground or opencast mines, we can collect data without any physical connections. Wireless sensor networks (WSNs) are well suited to monitor the movement, and it consists of sensor nodes which measure physical quantities and transmit the pre-processed measurement results to a base station. Developments in information and communications technology (ICT) support the collection, connection and analysis of data through sensing and monitoring of slopes in mines. This paper gives the detailed review on available low-cost wireless slope monitoring systems for opencast mines.

Review on low-cost wireless communication systems for slope stability monitoring in opencast mines

Slope stability is one of the primary problems faced by opencast mines. The conventional geotechnical sensors are monitored by technicians in the field and the available wireless monitoring systems like slope stability radar (SSR), light detection and ranging (LiDAR) are more expensive. Critical observations on recent low-cost wireless slope monitoring systems were presented. By deploying the wireless data transmission system using advanced antennas at respective slope instruments in underground or opencast mines, we can collect data without any physical connections. Wireless sensor networks (WSNs) are well suited to monitor the movement, and it consists of sensor nodes which measure physical quantities and transmit the pre-processed measurement results to a base station. Developments in information and communications technology (ICT) support the collection, connection and analysis of data through sensing and monitoring of slopes in mines. This paper gives the detailed review on available low-cost wireless slope monitoring systems for opencast mines.

Cost-Effective Millimeter-Wave Communications with Lens Antenna Array

MmWave communication is a promising technology for 5G wireless systems. However, the large number of antennas used and the wide signal bandwidth in mmWave systems render the conventional multi-antenna techniques increasingly costly in terms of signal processing complexity, hardware implementation, and power consumption. In this article, we investigate cost-effective mmWave communications by first providing an overview of the main existing techniques that offer different trade-offs between performance and cost, and then focusing our discussion on a promising new technique based on the advanced lens antenna array. It is revealed that by exploiting the angle-dependent energy focusing property of lens arrays, together with the angular sparsity of the mmWave channels, mmWave lens antenna system is able to achieve capacity-optimal performance with very few RF chains and using low-complexity single-carrier transmission, even for wideband frequency-selective channels. Numerical results show that the lens-based system outperforms the benchmark schemes for mmWave communications in both spectrum efficiency and energy efficiency.

Overlapped Phased Array Antenna for Avalanche Radar

Snow avalanche is a natural phenomenon, which annually causes infrastructure damage and leads to human casualties in many countries all over the world. As a result, a detailed hazard mapping is required to be able to understand the avalanche risk levels. Also, the scarcity of the areas suitable for constructing infrastructures in the mountains places a high premium on providing high precision hazard mapping. This paper presents the design and development of an advanced phased array antenna for an FMCW radar to produce a high resolution image of snow avalanche in range and cross-range. The proposed antenna is a 16-element fully populated phased array with ±14° azimuth beamwidth and ±22.5° fixed elevation angle. The designed phased array antenna has 14.4 dBi gain and −20.3 dB sidelobe level. In this design, subarraying overlapping technique has been used to eliminate undesirable grating lobes by means of spatial antialias filtering. A phased array power divider is proposed to allow tapering of the amplitude of the elements to achieve low sidelobe level.