In today’s world, communication must be instant and reliable, regardless of location. Operating from 37 to 52 GHz, Q- and V-Bands open the door to significantly larger data pipelines; however, reaching these higher frequencies presents a new set of technical challenges. While many feeder links in the satellite communications (satcom) market today operate at Ka-Band, the push toward Q- and V-Bands is gaining momentum. This shift is being driven by the ever-growing need to move larger volumes of data, especially in satcom and Earth observation.
The Q- and V-Bands open far more spectrum, with bigger and more continuous bandwidths than Ka-Band, enabling higher data rates and more efficient transmission between satellites and ground stations. However, moving to higher frequencies presents challenges. For example, design becomes significantly more complex, and today, few commercial products operate effectively at 50 GHz and above. High-power systems are particularly challenging and typically rely on traveling-wave tube amplifiers (TWTAs). Although TWTAs are effective, they are expensive, complex to manufacture and have a limited lifetime.
This is where solid-state alternatives come into play, thanks to advances in semiconductor processes. The shift from GaAs to GaN, the industry migration to shorter wavelengths and the combination of low loss and waveguide combining make solid-state amplifiers a rival to TWTAs. In addition to similar performance, solid-state amplifiers offer advantages in cost, scalability, production speed and lifetime.
The Q- and V-Bands are also attractive due to the structure of the available spectrum. The Q- and V-Bands complement each other, and using both together maximizes spectral efficiency and ensures operators benefit from the available bandwidth.
ARTES PROGRAM AND SATELLITE NETWORKS
A new development in satcom is the ARTES program, a European Space Agency (ESA)-backed initiative designed to push the envelope in satcom technology. Filtronic recently secured a contract with ESA to develop RF solutions for next-generation satellite networks at Q- and V-Bands, as well as K- and Ka-Bands.
As part of ESA’s ARTES 4.0 program, Filtronic will design high-power RF solutions for next-gen satellite networks. The networks focus on cost-effective feeder links for ‘new space’ satellite payloads to enable high-throughput communications and efficient transmission. The satellite uses Q-Band for transmitting and V-Band for receiving, accessing a large bandwidth for higher data rates. This approach is key to enhancing broadband communication for satellite constellations, which are increasingly relied upon to meet the growing demand for data.
One key aspect of this project is its adaptability. While it is focused on LEO applications, the technology being developed can be adapted for use in medium Earth orbit (MEO) and geostationary Earth orbit (GEO) satellites. This flexibility can support a range of applications from commercial satellite networks to military communications, making it a resource for both civilian and defence sectors.
A persistent challenge in the industry is the volume of data these networks need to handle. While the K- and Ka-Band systems are currently sufficient, they are increasingly strained as data demands grow. With recent developments in higher frequency solutions, such as Q- and V-Bands, the work being done in this program is laying the groundwork for advancements.
The project’s goal is to create a flexible, high performance system that can operate across different orbits. By blending LEO, MEO and GEO satellite networks, it is possible to create a more resilient and efficient communication system that can better handle the increasing data load. Additionally, the potential defence applications expand the importance of the program. As the demand for secure and reliable space-based communications rises, technologies that can adapt to both commercial and military needs are becoming more valuable.
This program is setting the stage for future satcom systems that will meet the growing data demands of today’s connected world. It is an exciting time for space communications, and this initiative is a step forward in making commercially viable, robust satellite networks a reality.
SECURE BATTLEFIELD COMMUNICATIONS
Unlike lower frequencies, which tend to spread signals over a broader area, the narrower beam widths produced at higher frequencies are harder to intercept or jam. This makes mmWave frequencies like Q- and V-Bands particularly attractive for secure battlefield communications.
Although tactical communications using mmWave are still emerging, their potential for secure, high data rate transmissions is undeniable. With growing interest in using Q- and V-Band frequencies for military satcoms, a clear trend is emerging toward higher frequency solutions to enhance secure communications in both tactical and strategic settings. Additionally, they are more resistant to jamming, as the power required would exceed that of conventional systems.
The advances in semiconductor technology, particularly with GaN, have enabled improvements in the power density of devices operating at high frequencies. This has enabled Filtronic to push the boundaries of power output, providing solid-state solutions capable of supporting high-power applications, such as those required in defence communications.
mmWave technology is also making an impact in missile systems, particularly with mmWave seekers. These systems utilize high frequency signals to achieve superior spatial resolution, thereby enhancing the accuracy of target detection and tracking while maintaining the same level of protection from jamming in contested and congested environments. In the U.K., the defence sector is exploring high frequency solutions, displaying the military and government sectors’ increasing focus on next-gen systems to enhance secure communications. By combining GEO, MEO and LEO satellite systems with Q- and V-Band frequencies, these advancements will increase the security and resiliency of communications.
CHALLENGES AT Q- AND V-BANDS
High frequency systems bring many benefits but introduce thermal management challenges. As operating frequencies rise, device efficiency typically declines. While lower frequency devices may reach efficiencies of 40 to 50 percent, systems in V-Band often see efficiencies drop to just 10 to 20 percent. This means much of the input energy is converted into heat, creating a significant engineering challenge, especially in compact satellite and defence systems where space and weight are limited.
Historically, GaAs devices at these frequencies offered modest output power, helping mitigate thermal issues. However, with advances in semiconductor technology and a move to GaN, power output has increased significantly. Filtronic, for example, has increased power output by 4x to 5x within the same footprint compared to earlier designs. While this boost is essential to overcome atmospheric attenuation at Q- and V-Band frequencies, it damages the manageability of the thermal load.
Addressing these challenges requires a holistic approach. High performance thermal interface materials, die attach solutions and heat spreaders are all crucial for optimising heat extraction while maintaining mechanical reliability. Additionally, system-level design plays a key role. Combining multiple smaller devices into a module can evenly distribute heat and improve overall thermal stability. Continuous improvements in thermal management — from advanced materials to precision assembly techniques — will be key in enabling the reliable operation of high frequency, high-power systems in space and defence applications.
Scaling up production introduces a layer of complexity. Scaling from prototype to high volume manufacturing presents significant challenges since high frequency mmWave devices require precision at every step. Tiny imperfections in materials or interconnects can have a substantial impact on RF performance. Because of this, manufacturing techniques must be precise and require advanced processes that can handle the tight tolerances necessary for these high frequency applications. Additionally, supply chain security is a risk. Currently, many high-reliability packaging facilities are offshore, which raises security concerns, especially regarding critical applications in defence and infrastructure.
PROMISES AND CHALLENGES OF GAN
GaN is gaining traction in high-power and high frequency applications. With its properties such as a high breakdown voltage, excellent electron mobility and superior thermal conductivity, it is proving to be a disruptor in industries such as satcoms, radar and defence systems. Unlike materials such as silicon or GaAs, GaN enables more efficient and higher-power output, which opens up new possibilities for next-gen technologies.
However, as with most breakthroughs, these advantages come with challenges. One of the biggest hurdles, similar to Q- and V-Band challenges, is thermal management. GaN devices, especially those operating at mmWave frequencies, generate intense power densities. GaN devices tend to generate high heat densities with hot spots around transistor gates, creating a significant heat dissipation problem. Managing that heat is crucial for maintaining peak performance and extending the lifespan of devices.
The challenges are applicable in defence and space as well. These systems are designed to endure extreme conditions, from wide temperature fluctuations to exposure to radiation and mechanical stress. As a result, GaN packaging must do more than protect the device — it must keep things running smoothly in harsh environments. The packaging must ensure that thermal stability and signal integrity are maintained, even in harsh conditions such as the vacuum of space or on the battlefield.
Lastly, the heat generated by GaN demands a packaging solution that strikes the right balance. The materials used must withstand the intense thermal load while also accounting for the differences in thermal expansion between the device and traditional packaging materials. Without striking this balance, the device could face mechanical stress, cracking or delamination during thermal cycling, therefore disrupting its performance.
MATERIALS AND TECHNIQUES FOR HIGH FREQUENCY
To tackle the challenges of high frequency systems, the industry is exploring advanced materials and techniques. Technologists are testing sintered silver, particularly in die attach methods. This material offers high conductivity, void-free bonds that effectively draw heat away from the device, ensuring better performance while maintaining mechanical robustness. Sintered silver is especially appealing for industries such as aerospace, defence and satcoms, where high-reliability performance is crucial, particularly under extreme conditions like high temperatures and mechanical stress. It also has advantages in high volume production environments. For mission-critical applications, eutectic gold-tin (AuSn) bonding is the preferred choice. Its ability to handle rapid thermal cycling and vacuum environments makes it a reliable material for systems where stability and reliability are non-negotiable.
Additionally, substrate materials have a high impact on performance. For example, copper-tungsten (CuW) and copper-molybdenum (CuMo) are great choices because they offer a thermal expansion match to GaN and provide high thermal conductivity. This helps reduce stress at the interface and prolongs device life. Meanwhile, diamond heat spreaders can be used alone or combined with innovative cooling techniques, such as liquid cooling. Another popular choice is aluminium nitride (AlN), which balances thermal performance, electrical insulation and manufacturability — increasingly crucial as systems become more compact and power-dense.
The techniques used for packaging are also evolving to meet the demands of high frequency systems. Traditional wire bonding remains reliable; however, it can introduce inductance and loss, which limits bandwidth and efficiency. These limits are especially detrimental at mmWave frequencies. As a result, newer methods such as flip-chip mounting, embedded passive structures and 3D packaging are gaining traction. These approaches reduce interconnect lengths, minimise parasitic losses and optimise thermal paths, making modules more compact, lightweight and efficient. With the communication demands of today’s world, industries such as satcoms and defence are pushing further into the high frequency Q- and V-Band ranges.
As industries pursue these higher frequencies, challenges around thermal management, packaging and device reliability are becoming more pronounced. Yet Q- and V-Bands also open the door to advancements, with the potential to expand data capacity and spectrum, improving global connectivity and secure communications.
Pushing into these higher frequencies will continue to challenge the industry, especially from a design perspective. However, the progress underway today is laying the foundation for the next generation of high performance, resilient satellite networks, thanks to more data bandwidth capacity.
