Amplifier Technology: Reflecting the Change in the Industry

The satellite world is buzzing with the emergence of new HTS players in Geostationary Equatorial Orbit (GEO), Medium Earth Orbit (MEO), and mega constellations in Low Earth Orbit (LEO).

As users of technology, we all want more. More data, ubiquitous connectivity, and high reliability, so satellite operators are meeting our hunger for bandwidth by building more powerful satellites and smallsats in very high volume. However, these new satellites, both large and small, will need to be supported by more advanced ground equipment. This presents a variety of challenges for HPA manufacturers that are trying to satisfy demand for smaller, lighter, and cheaper amplifiers with equal or better reliability and performance.

Lofty Ambitions

The explosive growth of the smallsat sector is rocking the industry with a rise in data demand and governments that are committed to providing universal access. Satellites are being built and launched more cost-effectively with shorter development cycles. But what significance does this hold for the amplifier community? The promised deployment of thousands of small satellites from operators such as LeoSat, SpaceX, Sky and Space Global, and Telesat is surely set to drive a new requirement for suitable ground technology. But is this really the case?

“Given these developments, capacity is expected to dramatically increase,” says Communications and Power Industries (CPI) Satcom and Medical Products (SMP) Vice President of Business Development Gerard Charpentier. “Historically, this does not necessarily mean that a subsequent, immediate boom in ground equipment will follow. More likely, the investment in ground infrastructure will grow steadily over time as technological advances occur that either allow more user access or consume more bandwidth per transmission.”

Steve Richeson, vice president of sales and marketing at Mission Microwave, also does not expect a rush of new business. “Today, the smallsat sector generally supports the LEO sector; there is some demand for gateways in support of LEO operations,” he says. “In general, the smallsat industry as it stands today offers little opportunity for high power amplifier manufacturers. We are all keeping an eye on it, though.”

However, Canadian communications solutions provider Norsat predicts an enormous rise in the volume of ground equipment as the main effect of the smallsat boom. “With the target markets that the smallsat sector is going after, the volumes could be tremendous with amplifier and antenna demand being one or more order of magnitude higher than today,” says Brian Donnelly, vice president of sales and marketing at Norsat. “This will challenge the ground equipment manufacturers to be able to hit new low price points that may not have been feasible previously.”

From Advantech Wireless’ perspective, pushing the costs down is going to be the main challenge and this will result in fundamental changes in terminal manufacturing. With LEO bandwidth costs expected to hit the range of a few hundred dollars per MHz per month, the end users will expect a similar kind of reduction in the overall terminal cost. “That will require a totally different manufacturing process than the one is largely being used today,” says Cristi Damian, vice president, business development at Advantech Wireless. “For GEO satellites, we see the same trend. As we start transmitting more Ultra-HD 4K content, we need to use more bandwidth, or higher modulation rates. Both of them require proportionally larger SSPA power. A few years ago, a typical teleport would require 200-500W of RF power. Now it requires up to 10 KW of RF power.”

Another significant challenge for HPA manufacturers (in terms of smallsat development) will be supporting the handoff from one antenna to another when a satellite goes beyond the horizon. Donnelly explains that having two antennae on a terminal to track multiple satellites will have cost implications. The alternative would be to have one fast antenna, which may then require the antenna to feature extreme speed and acceleration to re-acquire a new satellite once the locked satellite breaches the horizon. There could also be new requirements for amplifiers if satellite operators are looking to share one amplifier between two antennae, or the amplifier may need to be outfitted with extra fast switching capability to mute or unmute when transitioning satellites.

Almost certainly, the rapid growth in the smallsat sector is set to fuel amplifier development. “Smallsat constellations operating at any frequency will dramatically increase the amount of overall available communications capacity, which history suggests could fuel consistent, stable growth in the industry — not only for the next two to three years, but potentially for the next decade,” says Charpentier.

Some emerging operators have ambitious plans for their satellites. The sheer number that will eventually be deployed creates unique and unprecedented challenges for ground equipment manufacturers. Steve Richeson sees the HPA sector pushing the envelope in terms of applications. “The new technology to reliably manufacture low Size, Weight, and Power (SWAP) and high power Ka-band products enables new applications for mobile terminals — actually increasing demand as applications that were impractical can now be practicable.”

Gallium Nitride: The Way Forward

Despite the challenges ahead, manufacturers are confident in their abilities to meet the changing demands, especially now that Gallium Nitride (GAN) technology has taken the amplifier market by storm. Solid-State Amplifiers (SSPAs) are gradually replacing Traveling Wave Tube Amplifiers (TWTAs) due to their high reliability and high performance. Prior to the availability of GAN-based semiconductors, a serious limitation of solid-state amplifiers was the inability to provide enough bandwidth for certain applications.

“The advent of GAN-based technology has changed that scenario for the better,” explains Charpentier. “Solid state amplifiers using GAN can accommodate higher frequencies and greater bandwidth applications much more readily than their predecessors. As more and more high and non-standard frequencies emerge, the development of GAN could not have come at a better time.”

CPI’s solid-state development efforts are taking advantage of the flexibility offered by GAN technology. In addition to allowing the team to develop SSPAs at higher frequency bands, GAN technology has also been helpful in enabling the company to increase Radio Frequency (RF) output power in more efficient ways.

“I would say that the technology is ahead of the market,” comments Damian. “We estimated massive data rate increase back in 2010, when we decided to start the Gallium Nitrate (GaN) SSPA development program. We have upgraded thousands of SNG trucks, maritime and airborne terminals to GaN technology. All these are now ready to operate to all extensions of DVB-S2X. This spring, we achieved 256 APSK transmission from a truck with a 400W C-band GaN SSPA and a 4.5m antenna and it worked perfectly. We could not get the same performance 10 years ago with an 800W amplifier and a 30M antenna.”

Traveling Wave Tube Amplifiers

Though many in the industry talk about the replacement of TWTAs, it should also be noted that Traveling Wave Tube (TWT) technology is also keeping up the pace with new satellite operator’s ambitious plans. Charpentier explains that TWTAs can offer power and bandwidth combinations that are not viable with SSPAs. “For instance, Ka-band TWTAs have been providing multiple hundreds of watts in this frequency range for some 15 years, long before SSPAs could accommodate these requirements,” says Charpentier. CPI’s product advancements in GAN and TWT help to increase RF power, develop new SSPAs in Q- and V-bands, and boost the RF power of TWTAs in those frequencies.

Where’s the Growth?

As the industry gradually transitions over the next two to three years, HPA sector growth is expected to come from different angles.

A great amount of growth will come from the mobility sector, which places extra demands on HPA technology. “We see major growth through design wins in innovative mobile and portable terminal designs, as well as in the replacement of TWT and earlier generation solid-state amplifiers in broadcast and gateway facilities,” says Richeson.

From CPI’s perspective, the aerospace In-Flight Entertainment and Connectivity (IFEC) market will be significant, as well as the growth in higher frequencies. “Higher frequencies such as V-band — and even W-band — will provide more bandwidth, which will be consumed by large data requirements in segments such as military and commercial broadband,” says Charpentier. He notes that the challenge in those bands is to design HPAs — and, more generally, uplink RF systems — with enough margin to compensate for atmospheric attenuation, as rain attenuation is even higher in V- and W-bands than in Ka-band.

Charpentier also believes that smallsat sector growth will bring industry stability. “Smallsat constellations operating at any frequency will dramatically increase the amount of overall available communications capacity, which history suggests could fuel consistent growth in the industry — not only for the next two to three years, but potentially for the next decade,” he says. Traditional Earth station operators and their suppliers should also benefit from the increased space capacity provided by smallsat constellations. In the shorter term there is expected to be some demand for ground infrastructure to manage Telemetry, Tracking, and Command (TT&C), as well as for the initiation of some communications programs.

Advantech’s Damian is in agreement in terms of smallsat sector potential, pointing out that it is “incredible” and “disruptive”. Advantech’s heritage in the field harks back to the company’s involvement in the Iridium and Globalstar projects, around 20 years ago - the precursors of today’s LEO and smallsat constellations. “The RF technology required to transmit thousands of carriers is quite different from the traditional SSPA used today in GEO applications. But the knowhow is here, and we are building on this long time expertise,” says Damian.

Advantech envisions growth in government applications such as border control, disaster recovery, satellite imagery, and military applications, coupled with great potential in upgrading older teleports to GaN SSPA technology. Damian explains that, in many of these teleports, the initial investment is recovered in 12 to 18 months of electricity savings alone. That said, the company is not dependent on a single customer or application. “Nobody can predict the market. For sure we will have many ups and downs. This is why we are addressing now several market verticals at the same time,” says Damian. “We have a very large portfolio of RF products, which extend from Satcom to Radar, or Troposcattering links . If the new generation of LEO satellites for satellite imagery will use X-band radars, than we have a product today. We see a lot of potential in this cross market synergy.”

A Bright Future

All HPA manufacturers are carefully watching the market and striving to anticipate its changes. Working with customers to tailor products and services will be key in terms of meeting the new challenges that the evolving market is bringing with it, whether that is meeting requirements for mobility applications, HTS, smallsats or Ka-band. Moving forward, dialogue with customers will be critical. For the new smallsat operators especially, requirements are not yet defined.

“Not all the companies launching the new satellite constellations are clear on their ground equipment requirements, which means suppliers must be careful during their design processes or risk developing products that may not be tailor-made for the customer base,” Donnelly explains. He goes on to add that there has not yet been much discussion about sizes, form factors, and weight of new ground equipment and that these issues will drive some interesting design challenges. However, with sufficient time, manufacturers should be able to meet the new requirements.

CPI’s Charpentier envisions a focus on antenna size, in which amplifiers play a critical role. “We believe the nature of the business going forward will be to minimize system footprints while improving performance, and so integrators will want to continue to minimize antenna size. Since there is an inverse relationship between antenna size and output power, the burden of more bandwidth and power will rest with HPA manufacturers.”

In terms of the wider amplifier market, Richeson points out that the number of vendors has grown rapidly. There is heavy competition as multiple companies have started re-selling products manufactured from a few sources in Asia. Key technological challenges for the future include the availability of advanced GAN devices and the limited supply of RF design engineers.

The advent of 5G could also provide a considerable opportunity for HPA manufacturers and Advantech will be carefully tracking developments. “LEO/MEO/GEO all have a potentially great contribution to the success of 5G, and are a perfect technological match,” comments Damian. “The amount of traffic that 5G is expected to generate will rely heavily on satellite backhauling. This will demand even more RF power in the teleports, and this is where we are focusing right now. We are working on a new generation of GaN based SSPAs that will have much higher linearity over a very wide bandwidth.”

This is an exciting period for amplifier manufacturers. There may be many challenges that lie ahead, but this is what manufacturers do best. They innovate while focusing on investment in research and development, and continue to produce models that are smaller, lighter, and more portable, yet can power even the most demanding applications. Above all, they relish the challenge. The industry may be in the midst of change, but it is these changes that propel technology forward. VS