Phased Array Antenna technology: Revolutionising 5G, SATCOM to Defense EW and Radars

Unlike traditional mechanically steered antennas, phased arrays use electronic control to manipulate the direction of the radio beam. This seemingly simple change unlocks a range of possibilities in communication, radar technology, and even weaponry. Phased array antenna technology is revolutionizing telecommunications and defense, offering unprecedented capabilities in 5G networks, Satellite Communications On-The-Move (SATCOM OTM), and phased array radars for warships, aircraft, and missiles. This article explores the fundamentals of phased array antennas, their operational advantages, and their critical applications in modern communication and defense systems.

The demands on wireless communications and radar systems have been steadily increasing as the need for accuracy, efficiency, and advanced capabilities becomes more critical. Many new applications require antennas that consume less power and have a lower profile than traditional mechanically steered dish antennas. For example, the ongoing New Space revolution plans to deploy up to 50,000 active satellites over the next decade, each with complex and varied orbits and waveforms that satellite communication (SATCOM) networks need to support. This necessitates SATCOM operators to create flexible and adaptable networks capable of operating on a myriad of different waveforms, orbits, and constellations, all while maintaining service quality and profitability.

Wireless electronic systems have long relied on dish antennas to send and receive signals. While dish antennas are cost-effective and efficient after years of optimization, they come with drawbacks such as slow steering, physical bulkiness, and limited adaptability in radiation patterns. As demands on wireless communications and radar systems increase, new technologies are required to meet the need for higher accuracy, efficiency, and advanced metrics. Phased array antenna technology emerges as a transformative solution, enabling rapid electronic steering, reduced size, and enhanced reliability across various applications, including 5G, SATCOM On-The-Move (SOTM), and military radar and electronic warfare systems.

Fundamentals of Phased Array Antennas

A phased array antenna consists of multiple individual radiating elements, each with the ability to adjust the phase of the signal it emits or receives. By dynamically controlling the phase of each element, the antenna can electronically steer its beam direction without moving any physical components. This capability enables rapid and precise targeting of signals, making phased arrays ideal for applications requiring agility and high performance.

Phased Array antenna principle

A phased array antenna is a collection of antenna elements assembled together such that the power from the transmitter is fed to the antennas through devices called phase shifters, controlled by a computer system. EThe fundamental principle of the phased array antenna is the phase-dependent superposition of two or more radiated signals. When the signals are in-phase, they combine together to form a signal of additive amplitude. When the signals are counter-phase, they cancel each other.

Each antenna in the array has an independent phase and amplitude setting to form the desired radiation pattern. This phase shift will introduce interference between the signals transmitted. which can alter the phase electronically, thus steering the beam of radio waves to a different direction.  The radiofrequency current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in the desired direction while canceling to suppress radiation in undesired directions.  The direction of radiation can be manipulated by changing the phase of the signal fed into each antenna element.

The phase shift is controlled by placing a slight time delay between signals sent to successive emitters in the array. Outside of the main beam emission direction, the beam intensity decreases. There are also sidelobes in the beam pattern because signals are periodic, but you do get a very strong beam along a specific direction.

The radiation pattern of each individual element constructively combines with neighboring antennas to form an effective radiation pattern called the main lobe. The main lobe transmits radiated energy in the desired location while the antenna is designed to destructively interfere with signals in undesired directions, forming nulls and side lobes. The antenna array is designed to maximize the energy radiated in the main lobe while reducing the energy radiated in the side lobes to an acceptable level.

The phase shift introduces interference between transmitted signals, manipulating the direction of radiation without physical movement. The phase shift is controlled by placing a slight time delay between signals sent to successive emitters in the array, resulting in a strong beam along a specific direction while minimizing side lobes and unwanted radiation.

Phased array antennas consist of multiple emitters used for beamforming in high-frequency RF applications. Beamforming is achieved by adjusting the phase difference between the driving signals sent to each emitter, allowing the radiation pattern to be controlled and directed without physical movement. This technology enables rapid electronic steering and multiple beam formations, significantly improving performance and reliability over traditional antennas.

Advantages of Phased Array Antennas

Power: One of the primary advantages of phased array antennas is the enhanced signal power. Unlike traditional antennas, the collective power of a phased array is the sum of the individual powers of each radiating element. This summation effect significantly increases the overall signal strength, allowing for more effective communication over long distances and through various environmental conditions. The increased power also enhances the antenna’s ability to detect and track targets in radar applications, improving overall system performance.

Beamforming: Phased array antennas excel in beamforming, the process of shaping the radiation pattern of the antenna to focus energy in specific directions. By precisely controlling the phase differences among the radiating elements, these antennas can produce a narrow and highly directional beam. This improved directivity results in better signal-to-noise ratios and reduced interference from unwanted directions. The ability to dynamically adjust the beam shape and direction enhances the performance of phased array systems in various applications, such as wireless communication, where targeted signal delivery is crucial.

Beam Steering: Traditional mechanically steered antennas require physical movement to change the direction of the beam, which can be slow and prone to wear and tear. In contrast, phased array antennas utilize electronic steering, which eliminates the need for mechanical repositioning. Electronic beam steering is much faster, more precise, and more flexible, allowing the antenna to quickly respond to changing conditions and requirements. This capability is particularly beneficial in dynamic environments, such as satellite communication and military operations, where rapid reconfiguration of the beam direction is essential.

Multi-Beams: Another significant advantage of phased array antennas is their ability to synthesize multiple beams simultaneously. By employing phase shifters, a phased array can generate hundreds of beams, each pointing in different directions. This multi-beam capability allows for efficient and concurrent coverage of multiple targets or areas, greatly enhancing the versatility and throughput of the system. In applications such as radar and telecommunications, the ability to handle multiple beams translates into increased efficiency and capacity.

Weight and Cost: Phased array antennas are generally lighter and less expensive than their mechanically steered counterparts, especially when considering high-resolution applications. The reduction in weight is advantageous for aerospace and satellite applications, where minimizing payload weight is crucial. Additionally, the lower cost of phased array antennas makes them more accessible for a wider range of applications, enabling advanced capabilities without prohibitive expenses.

Reliability: The design of phased array antennas inherently offers improved reliability. If one or a few radiating elements fail, the remaining elements can continue to function with only minor adjustments to the system. This redundancy ensures that the overall performance of the antenna is not significantly compromised by individual component failures. This reliability is critical in mission-critical applications, such as defense and aerospace, where consistent and dependable operation is paramount.

In summary, phased array antennas provide numerous advantages over traditional mechanically steered antennas, including increased power, enhanced beamforming capabilities, rapid and flexible beam steering, the ability to generate multiple beams, reduced weight and cost, and improved reliability. These benefits make phased array technology a superior choice for a wide range of applications, from communication and radar to aerospace and defense systems.

Applications of Phased Array Antennas

The New Space revolution aims to launch up to 50,000 active satellites over the next decade, requiring satellite communication (SATCOM) networks to support diverse waveforms and orbits. These networks must be flexible, adaptable, and capable of maintaining service quality and profitability. Traditional mechanically steered dish antennas cannot meet these demands due to their slow repositioning, single data stream limitations, and reliability issues.

In applications requiring rapid repositioning to new threats or users, the ability to transmit multiple data streams and operate over longer lifetimes at reduced costs is crucial. Engineers have turned to advanced antenna architectures, such as phased array antennas, to address these challenges and introduce new functionalities.

Satellite applications, particularly SATCOM On-The-Move (SOTM), leverage phased array antennas to enable Beyond-Line-Of-Sight (BLOS) communications, catering to mobile military ground vehicles, maritime vessels, and airborne platforms. SOTM technology allows vehicles equipped with satellite antennas to establish and maintain communication with satellites while in motion. This capability is crucial for maintaining connectivity and situational awareness in dynamic operational environments.

Phased array beamforming technology plays a pivotal role in SOTM by electronically steering beams without the need for physically moving antenna apertures. This electronic beam steering capability enables rapid and precise communication link establishment and maintenance, enhancing operational effectiveness. Despite its advantages, widespread adoption of phased array antennas in SOTM has been limited due to high implementation costs, particularly in terms of size, weight, power consumption, and overall system cost (CSWaP).

Modern SATCOM applications increasingly utilize active electronically scanned arrays (AESAs), which employ multiple transmit/receive modules (TRMs) for independent beam steering. Traditionally, AESAs used a bulky 3D brick configuration with boards connected via numerous connectors and cables. Recent advancements have shifted towards more compact 2D planar arrays, resembling printed circuit boards (PCBs) with surface-mount (SM) components. This planar design eliminates many connectors and cables, thereby reducing SWaP-C metrics (size, weight, power, and cost), improving reliability, and simplifying manufacturing processes.

By transitioning to planar array configurations, SATCOM systems benefit from enhanced efficiency and affordability, making them more viable for widespread deployment in military and commercial applications alike. These advancements underscore the ongoing evolution of satellite communication technologies towards more compact, reliable, and cost-effective solutions capable of meeting the demanding requirements of modern mobile communication platforms.

In addition to these requirements, there is a growing need to quickly reposition to address new threats or users, transmit multiple data streams, and operate over longer lifetimes while meeting aggressive cost targets. Some applications also demand the capability to nullify incoming blocking signals and maintain a low probability of intercept. To meet these challenges, engineers are turning to advanced antenna architectures like phased array antenna technology. Phased array antennas, which consist of multiple emitters, enable beamforming by adjusting the phase difference between the signals sent to each emitter. This allows for precise control and direction of the radiation pattern without any physical movement of the antenna. By utilizing electronic steering, phased array antennas can dynamically change the direction and shape of the radiated signals, enhancing functionality and performance in high-frequency RF applications.

Military Applications

Phased array radar systems have become essential components in modern naval warfare, enhancing the capabilities of warships across many navies. The rapid beam-steering capability of phased array radars allows a single radar system to perform multiple functions: surface detection and tracking (identifying ships), air detection and tracking (detecting aircraft and missiles), and missile uplink capabilities. Previously, each surface-to-air missile in flight required a dedicated fire-control radar, which limited the number of simultaneous targets that could be engaged. With phased array systems, a warship can control missiles during their mid-course flight phase and provide final guidance during the terminal phase using continuous-wave fire control directors. This rapid electronic steering of the radar beam enables the system to maintain fire control-quality tracks on numerous targets simultaneously while controlling several in-flight missiles.

One notable example is the AN/SPY-1 phased array radar, a core component of the Aegis Combat System deployed on U.S. cruisers and destroyers. This system can perform search, track, and missile guidance functions simultaneously, managing over 100 targets at once. Similarly, the Thales Herakles phased array multi-function radar, used by France, Russia, and Singapore, can track up to 200 targets. It can automatically detect, confirm, and initiate tracking in a single scan while providing mid-course guidance updates to MBDA Aster missiles launched from the ship.

The German and Royal Dutch navies have developed the Active Phased Array Radar System (APAR), showcasing further advancements in this technology. Ground-based anti-aircraft systems, such as the MIM-104 Patriot, also employ phased array radar to achieve similar operational benefits. These systems illustrate the significant enhancements in target tracking, engagement capability, and overall mission effectiveness that phased array radar technology brings to modern military operations.

System Considerations

When evaluating analog versus digital beamforming, several key factors come into play, including the number of beams required, power dissipation, and cost targets. Digital beamforming, which uses a data converter per element, typically incurs higher power dissipation but offers significant flexibility in creating multiple beams. This approach necessitates higher dynamic range data converters, as the beamforming that rejects interference occurs after digitization.

Analog beamforming, on the other hand, can support multiple beams but requires an additional phase adjustment channel per beam. For instance, a system with 100 beams would need 100 times the number of RF phase shifters compared to a single beam system. Consequently, the cost-effectiveness of data converters versus phase adjustment integrated circuits (ICs) can vary depending on the number of beams. Although analog beamforming generally has lower power dissipation by utilizing passive phase shifters, power consumption increases with the number of beams, especially if additional gain stages are needed to drive the distribution network.

A common compromise is the hybrid beamforming approach, which combines subarrays of analog beamforming with digital combination of the subarray signals. This approach, which is gaining traction in the industry, can adapt as technology evolves. Hybrid beamforming phased arrays combine the benefits of active electronically scanned arrays (AESAs) and digital beamforming phased arrays. These arrays use active phased array subarrays (e.g., 64, 128, or 256 elements, depending on system requirements) that are digitally combined, allowing the creation of clusters of simultaneous beams.

Designing phased array antennas is complex and requires careful planning of antenna elements and distribution networks to meet bandwidth and low-loss requirements. The goal is to create a SatCom product with low production and maintenance costs that delivers high data rates in areas lacking mobile cellular infrastructure. Design trade-offs must consider array size versus the power of each radiating element, impacting beam directivity and effective radiated power.

A critical aspect of phased array antenna design is the spacing of antenna elements. The system goals dictate the number of elements, and the physical array diameter is primarily driven by the need to keep each unit cell at less than half a wavelength to prevent grating lobes, which are unwanted energy radiations in other directions. This requirement imposes strict constraints on the size, power, and weight of the electronics within the array. At higher frequencies, unit cell length becomes smaller, necessitating greater integration of ICs, advanced packaging solutions, and simplified yet increasingly challenging thermal management techniques.

Building the entire antenna array involves overcoming several design challenges, including routing control lines, power supply management, pulsed circuitry, thermal management, and environmental considerations. The industry is pushing towards low-profile arrays that consume less volume and weight. Traditional plank architecture, which uses small PCB planks with perpendicular electronics fed into the antenna’s backside, has been optimized over the past 20 years to reduce antenna depth. Next-generation designs are moving to a flat panel approach, where the integration of ICs is sufficient to fit them directly on the backside of the antenna board. This significantly reduces the antenna’s depth, making it easier to fit into portable or airborne applications.

The advent of digital phased arrays, where each antenna element is controlled by analog-to-digital (ADC) or digital-to-analog (DAC) converters, represents a significant leap forward. This digital architecture enables precise digital beamforming and beam-steering, as well as direct digital sampling from each antenna element. A key advantage is the minimal impact on system performance in case of channel or antenna element failures.

However, challenges such as high research and development costs, power consumption, and thermal management constraints initially hindered widespread deployment of these systems. Expensive ADCs, DACs, and field-programmable gate arrays (FPGAs) posed significant cost and power consumption barriers. Moreover, concerns about latency, bus design inefficiencies, and power supply efficiency losses further complicated deployment.

In recent years, substantial improvements in semiconductor efficiency have mitigated many of these challenges, making next-generation phased-array systems more economically viable. Hybrid phased arrays have emerged as a compromise solution, integrating fewer digitizers (ADCs and DACs) placed further from the antenna elements. While this approach reduces power consumption and thermal concerns, it can lead to spectrum reduction and lower array efficiency due to sub-array constraints.

Efforts in power solution design have focused on point of load (PoL) converters, which optimize power delivery to FPGAs and other digital assets. These converters are crucial in meeting stringent FPGA power requirements, including voltage regulation, thermal management, and reliable power sequencing during startup and shutdown.

Looking ahead, as digital phased array technologies continue to advance, supported by robust power solutions, their deployment across military and space applications is expected to expand significantly. This evolution promises enhanced operational capabilities, improved reliability, and broader adoption across diverse military and commercial sectors.

Future Trends and Innovations

Phased array technology continues to evolve, driven by advancements in semiconductor technology. Integrated circuits (ICs) in SiGe BiCMOS, SOI, and bulk CMOS have combined digital circuitry and RF signal paths, achieving phase and amplitude adjustments in a single IC. This integration reduces size, weight, and cost, making phased arrays more viable for various applications.

The first fully integrated single-chip digital millimeter-wave (MMW) beamformer, developed by the University of Michigan, opens new possibilities for 5G communications. This technology improves vehicle-to-vehicle communication, autonomous driving, satellite internet, and national defense, offering high-speed data transfer and reliable connectivity.

Electrical and computer engineers at the University of Michigan have developed the first fully integrated single-chip digital millimeter-wave (MMW) beamformer, unlocking new potential for high-frequency 5G communications. This technology has the capacity to enhance vehicle-to-vehicle communication, autonomous driving, satellite internet, and national defense, among other applications.

Beamforming directs transmitting signals in specific directions, unlike traditional methods where signals radiate outward indiscriminately, leading to interference and inefficiency. This technique is crucial for MMW communication, which operates at high frequencies (24GHz to 100GHz), enabling high-speed data transfer—a key benefit of 5G.

While analog beamforming has been the norm, Professor Michael Flynn’s research focuses on digital beamforming, which offers advantages such as large-scale beamforming, precise beam patterns, flexibility, and the capability to generate multiple beams simultaneously. “With analog beamforming, you can only listen to one thing at a time,” Flynn explained. “But there are a number of new applications where you want to listen to multiple things at the same time, and switch quickly between them.”

Flynn’s team developed a 28GHz MMW digital beamformer with a custom-designed antenna array comprising 16 antennas on a single integrated circuit. This is the first known single-chip system to perform MMW digital beamforming. Its single-chip design improves power efficiency and size significantly over current digital systems. The digital nature of the system allows it to direct signals and “listen” in four different directions simultaneously. This capability means, for instance, that the device could track four airplanes or communicate with four satellites at the same time.

Flynn envisions applications like using digital beamforming on drones to provide emergency internet in disaster areas or deploying satellites to offer reliable internet access in rural regions. Digital wireless beamforming in mobile phones could ensure more dependable internet connectivity.

C-COM Satellite Systems Inc. is making substantial investments in R&D for next-generation antenna systems, aiming to disrupt the antenna design market. The company is in late-stage development of a potentially groundbreaking Ka-band, electronically steerable, modular, conformal flat-panel phased array antenna. Collaborating with the University of Waterloo’s Centre for Intelligent Antenna and Radio Systems (CIARS), C-COM aims to provide low-cost, high-throughput mobility applications over GEO, LEO, and MEO satellite constellations for land, airborne, and maritime sectors.

The project has received government funding, and C-COM owns all related intellectual property. The company has secured two patents for this new antenna system, with additional patents pending. This project aims to deliver revolutionary Ka-band and higher frequency (5G+/6G) antenna technology, capable of tracking multiple satellites in various orbits and potentially deployable on spacecraft and other airborne vehicles like high-altitude pseudo-satellites (HAPS) and drones.

Conclusion

Phased array antenna technology is revolutionizing wireless communication and radar systems, offering unmatched performance, reliability, and flexibility. As demands on wireless systems continue to grow, phased array antennas provide the advanced capabilities needed to meet these challenges and drive the future of communication and defense technologies.