We live in a world of communication, which must be instant and reliable, regardless of location. RF plays a critical role here.

We are increasingly seeing a new player entering the sector, and that is the Q/V band, consisting of the Q-band and the V-band covering frequencies from 47 to 52GHz. This combined band promises to more than double the bandwidth of current satellite systems, for faster, more-reliable communication for non-terrestrial and Earth-based networks alike. However, there are some technical challenges to address before the full adoption of this band.

Ka vs Q/V

The Ka-band, covering the spectrum between 26.5GHz and 40GHs, has been enormously important in satellite communications, but the Q and V bands are now being harnessed for next-generation networks. Together they offer a much wider spectrum, which means the new band can deliver faster data speeds to more users, with more efficient communication between satellites and ground stations. This makes it particularly attractive for industries like satellite communications and Earth observation, where the need for faster, more reliable data transfer is always needed.

However, switching to the Q/V band isn’t a simple task. There are some technical hurdles to surmount first, one of them the use of Travelling Wave Tube Amplifiers (TWTAs), which to date have been the well-established, go-to solution. Although these devices provide high power amplification, they are expensive, complex to manufacture and have limited lifetime.

Solid-state technology

Solid State Power Amplifiers, or SSPAs, are a good alternative to TWTAs, particularly those SSPAs that are built with Gallium Nitride (GaN). This type offer similar performance to TWTAs but are smaller, simpler to make, more cost-effective and have a longer lifetime, often extending beyond 15 years. In satellite communications, size, weight and power of components is always a sensitive parameter, and especially for satellites used in military or deep-space missions, there are strict volume and weight limits. Overall, the lower costs and simpler and faster production, make SSPAs highly suitable for cheaper and more scaleable satellite systems. This makes solid-state amplifiers a powerful solution, which is exactly what’s needed for high-frequency systems like the Q/V band. And, as semiconductor nodes continue to shrink — from 0.15 microns to even smaller gates length < 100nm — these devices will only become better performing and cheaper.

Advanced satellite communications

For many satellite operators, the Q/V band is the next step. This band doesn’t have the same level of atmospheric attenuation problems that come with higher frequencies.

A great example of Q/V band technology in action is the European Space Agency’s ARTES initiative, which is driving forward the development of advanced satellite communications. Filtronic has secured a contract with ESA to develop cutting-edge RF solutions for next-generation satellite networks, at Q/V band, as well as the K and Ka bands.

The project focuses on developing high power, high linearity feeder links for satellite payloads. To make this work, different frequency bands are used for specific tasks — the Q-band is used for the downlink, from satellite to ground stations. The high-power feeder link enables high data throughput to meet the needs of expanding New-Space constellations.

For receiving data on the satellite, the V-band is used, which allows access to large bandwidth for significantly higher data rates. This setup makes for a much more efficient data transmission and plays a key role in boosting broadband access. It’s especially important for mega constellations, which are essential for meeting the growing global need for fast and reliable data.

Secure communications

Beyond boosting commercial satellite services, the Q/V band holds great potential for secure communications, particularly in defence and military applications. The narrower beam width at higher frequencies is less susceptible to interception or jamming, which is crucial for military-grade communication systems.

As frequencies increase, the signal becomes more focused. Lower frequencies spread out, making them easier to intercept. But at millimetre-wave frequencies like the Q and V bands, the signal is more targeted and less vulnerable to interference. This makes this band ideal for secure communications, particularly in sensitive, high-risk environments like battlefield operations. They are also harder to jam with interferers as the power required would be beyond conventional systems.

While tactical communications at millimetre-wave frequencies aren’t widespread yet, their potential for better security and more efficient data transmission is driving growing interest within the defence sector.

Higher frequencies are also improving missile technology, particularly in millimetre-wave seekers. The increased resolution of radar and detection systems at these frequencies allows for enhanced spatial awareness, crucial for pinpointing targets with greater accuracy. With the same protection from jamming in contested environments.

The thermal challenge

As promising as Q/V band is, one major challenge it faces is heat management. Higher frequency devices are less efficient, so naturally convert more power into heat, which becomes especially problematic in space or other extreme environments where space and weight are at a premium and thermal management difficult.

The good news is that advances in semiconductor technology, particularly in the aforementioned GaN, are helping to address this. With improvements in GaN, including smaller gate lengths and more efficient designs, it’s possible to increase power output whilst improving efficiency.

To tackle thermal issues, materials like copper-tungsten or diamond heat-spreaders can be used and potentially combined with innovative cooling techniques, such as liquid cooling. These solutions are critical to ensuring systems continue to function effectively in the challenging environments of satellites and military operations.

GaN is key in these efforts. Its high breakdown voltages and excellent thermal conductivity make it perfect for high-frequency applications. However, it’s not without challenges. GaN devices tend to generate high heat with hot spots around transistors, sometimes reaching over 300°C, which can lead to system failures without effective thermal management.

At Filtronic we are tackling thermal management by using waveguide combined amplifier structures, providing very high power, whilst spreading thermal loads across multiple devices instead of concentrating them in one spot. Along with conventional forced-air cooling methods, there’s also the option to use liquid cooling for high-power configurations, giving more flexibility for future system designs.

Significant potential

The Q/V band holds significant potential to transform satellite communications, offering faster speeds, more secure connections and greater efficiency. Whilst there are challenges to overcome — from system design to thermal management and GaN production — the industry is making great strides toward solving them.

With innovations in semiconductor technology, such as solid-state amplifiers, Q/V band will play a key role in the future of communications. Projects like the ARTES initiative and the work happening at companies like Filtronic are pushing this technology forward – and we’re just scratching the surface of what is possible by harnessing this band.

The Q/V band is bringing us closer to a future where data bandwidth capacity will be significantly increased. Whether it’s for global networks or scientific missions, the future is looking bright and Q/V band is going to be at the heart of it.

By Tudor Williams, Chief Technology Officer at Filtronic (Filtronic – RF, microwave and mmWave communication solutions)https://filtronic.com/