Wireless electronic systems have been relying on dish antennas to send and receive signals. These systems have been widely used where directivity is important and many of those systems work well at a relatively low cost after years of optimization. These dish antennas having a mechanical arm to rotate the direction of radiation does have some drawbacks, which include being slow to steer, physically large, having poorer long-term reliability, and having only one desired radiation pattern or data stream.
As a result, engineers have pushed toward advanced antenna architecture such as phased array antenna technology to improve these features and add new functionality. 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, which can alter the phase electronically, thus steering the beam of radio waves to a different direction. The result is that 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.
The radio frequency 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 a desired direction, while cancelling 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.
Phased arrays were invented for use in military radar systems, to steer a beam of radio waves quickly across the sky to detect planes and missiles. Phased array antennas are electrically steered and offer numerous benefits compared to traditional mechanically steered antenna such as low profile/less volume, improved long-term reliability, fast steering, and multiple beams. With these benefits, the industry is seeing adoption in military applications, satellite communications (satcom), and 5G telecommunications including connected automobiles.
Phased array antennas are also important for applications such as SATCOM On-The-Move (SOTM) which offers a means for Beyond-Line-Of-Sight satellite communications. Satcom on the Move (SOTM), or satellite communications on the move, is a phrase used in the context of mobile satellite technology, specifically relating to military ground vehicles, Maritime and Airborne platforms. The basic principle behind Satcom On The Move is that a vehicle equipped with a satellite antenna is able to establish communication with a satellite and maintain that communication while the vehicle is moving. Ubiquitous SOTM requires mobile-based tactical ground terminals with reduced cost, size, weight and power (CSWaP). Phased-array beamforming antenna technology enables fast electronic beam steering without moving antenna apertures and is a key technology enabler for SOTM. However, phased arrays have yet to be widely deployed mainly because of high implementation cost.
Military requirements for phased array antenna
Expanded mission areas and the implementation of additional data routing resulting from future warfighting capabilities place more demand on data distribution services in the form of higher data bandwidths and reduced latencies. These demands require improvements in Radio Frequency (RF) spectrum utilization and advances in antenna technologies. Digital array antenna technology promises to enable these improvements by dramatically increasing operational flexibility.
Semiconductor IC-based phase adjustments can be made in nanoseconds such that we can change the direction of the radiation pattern to respond to new threats or users quickly. Similarly, it is possible to change from a radiated beam to an effective null to absorb an interferer, making the object appear invisible, such as in stealth aircraft. These changes in repositioning the radiation patterns or changing to effective nulls can be done almost instantaneously because we can change the phase settings electrically with IC-based devices rather than mechanical parts. An additional benefit of a phased array antenna over a mechanical antenna is the ability to radiate multiple beams simultaneously, which could track multiple targets or manage multiple data streams of user data. This is accomplished by digital signal processing of the multiple data streams at baseband frequencies.
The AN/SPY-1 phased array radar, part of the Aegis Combat System deployed on modern U.S. cruisers and destroyers, “is able to perform search, track and missile guidance functions simultaneously with a capability of over 100 targets.” Likewise, the Thales Herakles phased array multi-function radar used in service with France, Russia and Singapore has a track capacity of 200 targets and is able to achieve automatic target detection, confirmation and track initiation in a single scan, while simultaneously providing mid-course guidance updates to the MBDA Aster missiles launched from the ship. The German Navy and the Royal Dutch Navy have developed the Active Phased Array Radar System (APAR). The MIM-104 Patriot and other ground-based antiaircraft systems use phased array radar for similar benefits.
Phased array radar systems are used by warships of many navies. Because of the rapidity with which the beam can be steered, phased array radars allow a warship to use one radar system for surface detection and tracking (finding ships), air detection and tracking (finding aircraft and missiles) and missile uplink capabilities. Before using these systems, each surface-to-air missile in flight required a dedicated fire-control radar, which meant that radar-guided weapons could only engage a small number of simultaneous targets. Phased array systems can be used to control missiles during the mid-course phase of the missile’s flight. During the terminal portion of the flight, continuous-wave fire control directors provide the final guidance to the target. Because the antenna pattern is electronically steered, phased array systems can direct radar beams fast enough to maintain a fire control quality track on many targets simultaneously while also controlling several in-flight missiles.
The Navy needs a digital communications array to realize simultaneous, multichannel Tx and Rx capability. The digital communications array is a key enabler for higher data throughputs and reduced latency needed to engage evolving threats and enabling significant improvement in utilization of spectrum. This must be done while pushing the boundaries of signal integrity, dynamic range, isolation of signals and resistance to interference to maximize link performance. No technology currently meets all these requirements.
Digital arrays are not off the shelf available; but rather, industry contractors develop digital arrays in response to acquisition efforts. The commercial development of multi-beam 5G networks will focus on small picocells. Lower power levels and reduced linearity challenge leave a significant gap preventing commercial technology from being useful in Navy applications.
Defense Advanced Research Projects Agency (DARPA) efforts have made digital arrays a more off the shelf technology. Notable among these is the Arrays at Commercial Time Scales (ACT) and Millimeter-wave Digital Arrays (MIDAS) program. These programs focus on the transceiver and beamforming functionality of the array as opposed to the aperture. However, this technology is still not off the shelf and integration work would be required to meet the digital array needs even using this technology. The Navy must overcome some technology risks with a critical one being the development of digital array technology that can operate at the necessary bandwidths and frequencies while in complex RF environments.
The Navy seeks to expand and refine the battlespace by improving and expanding tactical network functionality. Increased data throughput is needed to enable the flow of more data and support of new mission areas. Decreased latency is needed to enable new and compressed kill chains against advancing threats as well as larger networks. Increased network throughput and decreased latency will be attained by developing 4-channel Transmit (Tx) and Receive (Rx) capability for digital communications arrays. The level of improvement in the fielded system will depend on the topology, size, and operation of the network. For large, half-duplex (i.e., cannot transmit and receive simultaneously) networks of four-beam nodes having all nodes connected along a line, the level of throughput improvement will approach a factor of 2. For large, half-duplex networks of four-beam nodes having topologies where all the nodes are connected to each other, the throughput improvement will approach a factor of 4. For other networks, the improvement will be somewhere in between. Of course, the fielded system may have a different number of beams per node. Four was chosen based on engineering judgement as a compromise between complexity, technical challenge, and capability improvement.
Navy’s multidomain tactical communications system
The Defense Innovation Unit has released solicitations for a multidomain tactical communications system . The first solicitation seeks proposals for a satellite communication antenna system designed to support multiple links in K-, Ka-, S-, X-, C- and Q-band signals and can be installed aboard DDG 1000-class ships. The Department of Defense wants a satcom antenna that could be integrated into ground stations and other ships. DIU will test the capability of the system to operate in a maritime environment and evaluate the platform’s susceptibility to electromagnetic interference, shocks and vibrations.
Isotropic Systems, a leading developer of transformational broadband terminal technologies, announced an antenna evaluation and development contract with the Defense Innovation Unit (DIU) to test the ability of its patented multi-beam antennas to unlock high-powered bandwidth aboard next-gen Naval vessels at sea. As the U.S. Navy expands the size and communications capabilities of its global fleet, the DIU is reviewing Isotropic Systems’ patented beamforming antenna technologies and circuits as an enabler to fuse multi-band, multi-orbit commercial and military capacity to deliver intelligence data at the tactical edge over a single platform.
ThinKom Wins Defense Innovation Unit Contract
ThinKom Industry Leading and Commercially Available Phased-Array Antenna to Be Evaluated as Enabling Technology for U.S. Navy Future Shipboard Satcom Requirements. The Defense Innovation Unit (DIU) has awarded a contract to ThinKom Solutions to test and evaluate one of the company’s commercial off-the-shelf (COTS) aeronautical phased-array antenna systems as a solution for next-generation communications on U.S. Navy ships.
Under the seven-month contract, ThinKom is delivering a ThinAir® Ka2517 antenna system for on-board testing to meet U.S. Navy requirements for Multi-Domain Tactical Communications (MDTC). The Ka-band antenna, based on the company’s patented VICTS technology, will demonstrate the capability to be integrated onto a U.S. Navy ship. A concurrent design study phase will evaluate performance modifications requested by the Navy.
ThinKom’s COTS Ka2517 satellite antenna meets the DIU requirements for low-cost, low-risk, proven technology for use on U.S. Navy ships, such as the USS Zumwalt (DDG-1000). Photo: U.S. Navy. DIU is a U.S. Department of Defense organization focused exclusively on fielding and scaling commercial technology across the U.S. military to help solve critical problems. Through its agile processes, contract authorities and diverse team of experts, DIU has reduced the time it takes to identify a problem, prototype a commercial solution and implement it into the field to 12 to 24 months.
ThinKom’s industry-leading VICTS phased arrays are currently installed on more than 1,550 commercial aircraft and have accrued more than 17 million flight hours, demonstrating mean time between failure (MTBF) rates well in excess of 100,000 hours. The Ka2517 terminals are in full production and currently operational on a fleet of U.S. government aircraft.
“ThinKom’s VICTS technology currently meets all of the DIU requirements for a low-cost, low-risk COTS solution that can be deployed on a DDG-1000 class destroyer,” said Bill Milroy, chief technology officer for ThinKom Solutions. “With millions of hours of service under the extreme dynamic and environmental conditions of modern commercial and military jet aircraft, ThinKom’s low-profile, compact VICTS antennas are ideally positioned to meet the Navy’s performance requirements on a platform at sea.”
“Our VICTS phased-array antennas are also uniquely capable — and proven — to provide uncompromising emission controls to meet the most stringent requirements for precision sidelobe control and grating lobe suppression, which are critical factors on a modern naval ship. Additionally, VICTS arrays, operating across the spectrum from C-band to W-band, have been verified by multiple third-party system integrators to be RF compatible with low radar cross section and low observable platforms and installations. Sidelobes are suppressed to enhance the low-probability-of-detection/interception and anti-jamming characteristics of the antenna, even when intentionally scanning to low elevation angles.”
ThinKom’s VICTS antennas have successfully completed multiple ground and in-flight tests demonstrating seamless interoperability across satellites in low, medium and geostationary orbits with extremely fast switching speeds of less than one second and very high data throughput rates. In all cases, ThinKom antennas have demonstrated unmatched spectral efficiency, beam agility, interference control, low-angle tracking and seamless inter-constellation operation. .
Phased Array Antenna for SATCOM Applications on Mobile Platforms
ReQutech and Forsway together with a research team from the Linköping University of Technology have collaborated to develop a new Phased Array Antenna solution for Satcom applications on mobile platforms. The proposed system aims to enhance the broadband coverage in areas where cellular network is not available and for high-end applications such as connected vehicles. The project plans to deploy the newly developed flexible, Phased Array Antennas on moving platforms for satellite communication (SatCom), Communication-On-The-Move (COTM), in combination with the next generation of Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) satellites.
Amazon marks breakthrough in Project Kuiper development, reported in Dec 2020
Ka-band is a frequency range that is commonly used for satellite communications. Ka-band offers advantages like wide bandwidth and smaller wavelength, leading to better performance and smaller antenna systems. The most effective way to reduce terminal production costs is to decrease the size, weight, and complexity of its antenna. This is difficult to do in the Ka-band, which requires more physical separation between transmit and receive antennas to cover its wide frequency range. For this reason, legacy Ka-band antennas place the transmit antenna and receive antenna next to one another, requiring a larger surface area and increasing production costs.
Project Kuiper has hit another key milestone on its path to delivering fast, affordable broadband through a constellation of 3,236 low Earth orbit satellites. We recently completed initial development on the antenna for our low-cost customer terminal, a critical part of the Kuiper System that allows customers to connect to satellites passing overhead. The Ka-band phased array antenna is based on a new architecture capable of delivering high-speed, low-latency broadband in a form factor that is smaller and lighter than legacy antenna designs. Our prototype is already delivering speeds up to 400 Mbps (Megabits per second), and performance will continue to improve in future iterations.
Our phased array antenna takes a different approach. Instead of placing antenna arrays adjacent to one another, we used tiny antenna element structures to overlay one over the other. This has never been accomplished in the Ka-band. The breakthrough allows us to reduce the size and weight of the entire terminal, while operating in a frequency that delivers higher bandwidth and better performance than other bands. Our design uses a combination of digital and analog components to electronically steer Ka-band beams toward satellites passing overhead.
The result is a single aperture phased array antenna that measures 12 inches in diameter, making it three times smaller and proportionately lighter than legacy antenna designs. This order of magnitude reduction in size will reduce production costs by an equal measure, allowing Amazon to offer customers a terminal that is more affordable and easier to install.
Phased Array Antenna Market
Key Players in the Phased Array Antenna Market are : ALCAN Systems, Viasat Antenna Company
Phasor Inc, C-COM Satellite Systems, Kymeta, Anokiwave, Ball Aerospace, Chengdu Tianjian Tech, Sichuan SIP Electronic Technology, KEYCOM, Chengdu Ruidiwei, Actenna Technology,