Broadband Flat Panel Antennas: A Paradigm Shift for High-Speed Rail Connectivity
Staying connected has never been so important. It tops the list of priorities for pretty much everybody today, and this is becoming a very hot issue for train operating companies.
The ability to offer ubiquitous broadband access to passengers is a differentiating factor and reliable broadband connections on board puts any passenger rail company at an advantage over competitors and unconnected transport alternatives. Additionally, this capability is essential for rail operations, supporting applications such as scheduling, track condition monitoring, logistics updates, crew communications, security and telematics that monitor the train performance and health of systems on board.
Basic rail connectivity solutions available today rely heavily upon oversubscribed terrestrial wireless services, which are not uniform and can degrade rapidly in more densely populated areas, as well in regions where coverage is poor, such as outside city centres.
SATCOM Antenna Technology
The one, ubiquitous means of ensuring connectivity on board trains is to connect via satellite. Satellites can be accessed anywhere, and they provide a reliable means of communication. To access one, all that is required is a clear line-of-sight to the satellite. Satellite communications (SATCOM), working in complement with terrestrial wireless connectivity, has the potential to enable universal, consistently powerful broadband access for rail passengers and operators, but only with powerful and reliable SATCOM antenna technology.
SATCOM antenna technology has come a very long way, and the growing demand for mobility has seen it pushed even further. The rise in popularity of the smartphone, the tablet and other mobile devices has brought data-centric activity to the forefront. In addition, people want to use these devices no matter where they are to run a plethora of applications from social media, web browsing, streaming services, email – and much more. This need for “always on” connectivity has created a demand for broadband-capable antennas that can meet the requirements of performance and much higher throughput than ever before, and for rail specifically, the requirement for a suitably rugged, reliable and low profile form.
Flat Panel Antennas
So why flat panel antennas? The rail industry is under pressure to cater to the broadband needs of passengers, many of whom are business travellers and commuters that require access to their work email, internet and social media. Until now, rail operators who wished to deploy SATCOM networks have depended upon traditional parabolic antennas that employ mechanically steered mounts to enable the dish to rotate to maintain pointing towards the satellite and to avoid interference. This requires complex, motorised systems with many continuously moving parts. When they do fail, it takes time for parts to be obtained in order to repair them, which involves the train being taken out of service. Furthermore, these traditional antennas are bulky and must sit under large radomes, affecting their clearance and ability to fit beneath tunnels.
It’s not ideal. But there is an alternative to large, domed antennas – very low profile, solidstate, electronically steered antenna technology. These are sometimes called Flat Panel Antennas, but there is a subtle difference in the latest developments.
Flat Panel Antennas (FPAs) have been in use since the 1980s. Narrowband FPAs, which operate in L-Band, can only produce moderate connectivity speeds and airtime can be prohibitively expensive. The new development is for “wideband” FPAs (in the Ku and Ka frequencies) which have the potential to empower true broadband connectivity. However, there have been two principal factors that have held their mainstream deployment back – cost and performance. They are complex pieces of technology and that is why it has taken time to develop FPAs that can finally meet expectations and price points that will enable them to hit the mainstream market. In a report by Northern Sky Research, NSR’s Flat Panel Satellite Antennas, 2nd Edition, published in February this year, it was forecast that cumulative FPA equipment sales will reach $9.1 billion by 2026.
A Revolution in the Satellite Communications Market
It may also help to take a brief look at what is going on in the satellite sector at the moment. There is a revolution occurring in the satellite communications market. Traditional wide-band geosynchronous (GEO) satellites are being designed for mobility with very powerful, interlocking spot-beam coverage areas. These are also called GEO-HTS satellite constellations, and include operators like Intelsat and SES. Additionally, new small satellites, which were previously the preserve of the scientific and academic communities, have proved to be highly capable and are moving into commercial deployment.
The developments in the market mean that small satellites in Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) will provide high throughput connectivity and therefore can deliver mobile broadband applications in more locations globally. There are several LEOHTS mega constellations on the table that will be deployed in the near future such as LeoSat, OneWeb and SpaceX. The wide-band FPA will be the key enabler for both the GEO-HTS and LEO/MEO constellations, empowering the delivery of mobile broadband services to passenger vehicles globally. There are several manufacturers of Flat Panel Antennas that are working towards commercial deployment and they use different technologies. Therefore, it is important to point out that different FPAs will have different capabilities and different strengths in different applications.
It is important to realise that not all FPAs are the same. Certain FPAs will be more suitable for use in the consumer market with lower cost but also lower performance, whereas others will be highly suited to mission critical enterprise communications applications. Consideration must be given to the requirements of the user. What applications will be run over the service? What level of performance is required? Can the user withstand any interruption in service? How robust, powerful and flexible is each technology?
Flat Panel, Electronically Steerable Antennas
Phasor will be making its unique Electronically Steerable Antenna (ESA) available to the high-speed rail market for commercial service in 2018. As a flat panel, software-defined antenna, this will not only meet but exceed the requirements of the market, which necessitates enterprise-grade connectivity to meet the demands of on-board users and operations. Its sleek and extremely compact design (under 2 inches high), will allow it to conform to the train roof and it will only require nominal maintenance as it is completely solid state with no moving parts. The Phasor antenna is also “future proof”, and it will operate and interoperate between GEO-HTS and LEO/MEO constellations in the same frequency. It is able to track two satellites simultaneously – essential for LEO small satellite systems. It is part of a wave of new antennas that will soon come to market to accommodate the insatiable demand for mobility, which is driving these mega constellations.
Changes in Satellite Technology
Antenna developers must constantly be several steps ahead to prepare for the changes that are to come in satellite technology and capabilities. One size will not fit all in this market, so IT managers and rail operators will need to carefully assess their connectivity requirements in order to make the right choice.
The market for mobile broadband is set for explosive growth across all market sectors, and the high-speed/passenger rail market is integral to this, and demands a very high standard of connectivity. Phasor looks forward to serving this market with a highly reliable, high-performance ESA that redefines the on-board connectivity experience.
