Article by RFMW CEO Joel Levine

In 2024, the RF and microwave industry remains at the forefront of telecommunications, defense, and aerospace, where the demand for higher frequencies and bandwidths is soaring. The deployment of 5G and increasing reliance on satellite communications will have significant impacts throughout the year. The industry also faces challenges, including needing cost-effective, miniaturized, and energy-efficient components. Rather than attempting to cover every application, I’ve decided to focus on some of the important and some, like quantum, that are years away from realization but will be a massive market for us when they arrive.

Reconfigurable Surfaces

The evolution of RF and microwave technology is closely linked to materials science, and one of the most promising technologies right now is reconfigurable surfaces that control the phase, amplitude, frequency, and polarization of incoming electromagnetic waves. By adjusting these parameters, these surfaces can direct or shape the propagation path of these waves. In wireless networks, they can be used to improve signal quality by redirecting signals towards intended receivers. Since they can more efficiently direct signals, they can reduce the DC power requirements of transmitters, which is a benefit for IoT devices and other battery-operated devices in which power efficiency is crucial.

The potential applications of reconfigurable surfaces go beyond improving wireless communications. They could be pivotal in areas like radar technology, medical imaging, and even in the development of cloaking technologies that make objects less detectable to electromagnetic waves.

Advances in Packaging

Advanced packaging technology will play a crucial role in the future development of microwave components. By reducing the distance between interconnected components, signal transmission can be faster and more efficient and advanced packaging techniques can help reduce signal loss and crosstalk between components, improve heat dissipation, and reduce costs.

One impressive advancement is Advanced Glass Packaging Technology (AGPT) developed by ED2 Corporation, which uses fused silica, a type of synthetic quartz, as the primary substrate in heterogeneous semiconductor packaging. Fused silica has exceptional thermal conductivity and a low dielectric constant, which enables efficient heat dissipation and faster signal transmission within the package. This improves performance and stability, especially for high-power and high-frequency applications.

AGPT (and heterogeneous semiconductor packaging in general) combines multiple types of semiconductor materials within a single package, including silicon and compound semiconductors such as gallium nitride alone or in combination. AGPT is well-suited for 2.5D and 3D integration techniques, where multiple chips are stacked vertically, which makes it possible to create highly complex multifunction modules with reduced footprints and improved performance.

Another significant development is PolyStrata technology from Nuvotronics. This Cubic Corporation subsidiary has spent the last 16 years developing the technology, which resulted in the world’s first 3D air-dielectric circuit board. PolyStrata technology is an air-dielectric circuit board that uses tiny, metal-coated channels embedded within a polymer substrate to carry electrical signals. The channels, known as micro-coaxial transmission lines, offer superior electrical properties compared to traditional planar circuits. Circuits designed with the technology have been shown to show a 10 to 100 times improvement in size, weight, and power.

The technology also delivers lower loss, higher isolation, better thermal management, and the ability to handle high RF power levels. In addition, PolyStrata allows seamless integration of devices fabricated in different technologies, such as GaN, SiGe, and silicon, within a single package. The result is smaller, lighter, and more efficient, components with superior electrical and thermal properties than traditional planar circuits. The Nuvotronics wideband 90-degree hybrid coupler family showcases these properties well.

Integration of AI and Machine Learning

We’ve all been hearing about AI for years, but when OpenAI launched ChatGPT, it finally became something tangible for mere mortals, and it’s now virtually impossible to read the news without constantly being bombarded with the latest developments. That said, AI and machine learning will play a significant role in RF and microwave technology because AI algorithms can optimize network performance, predict the need for maintenance, and enhance signal processing capabilities. Integrating AI in RF systems will lead to more intelligent, adaptive, and efficient communication networks.

Satellite Communications

While it has yet to happen, Starlink and eventually other satellite broadband providers using low Earth orbit (LEO) satellites will need spectrum higher than Ka-band. V-band at 40 to 75 GHz is a likely target, as well as E-band (60 to 90 GHz) because they offer immense available spectrum required to achieve higher data rates that will ultimately be needed for applications such as high-definition video streaming, large data transfers, and “direct-to-cell” wireless services. The next step for cellular technology is the integration of satellite networks with terrestrial microwave systems that will expand coverage to places still underserved (or not served at all) by terrestrial networks.

This will require ground stations and user terminals capable of communicating effectively with terrestrial networks and satellite constellations. Developments in microwave antenna design, such as phased array antennas, allow for more precise and dynamic beamforming and enable rapid repositioning of antenna beams, essential for tracking satellites in lower orbits.

Microwave Technology In Defense Systems

The defense industry in the US is currently undergoing its greatest challenges since the end of the Cold War, as stocks of everything from ammunition to air defense systems must be replenished after two years of war in Ukraine and, most recently, supporting the Israeli Defense Force. From a technological perspective, advances in microwave technology for defense will significantly improve, spanning communication and surveillance to weaponry and electronic warfare. Microwave technology advancements will enable radar systems to achieve higher-resolution imaging, which is crucial for accurately identifying and tracking smaller or more distant targets. Improvements in Active Electronically Scanned Array (AESA) radars powered by GaN devices will continue to replace vacuum electron devices to deliver RF power and allow for more agile and accurate tracking of multiple targets simultaneously.

Although lasers get most of the media attention, high-power microwave (HPM) direct energy weapons will play an increasingly important role in the coming years because they have benefits that lasers do not. For example, while microwave and lightwave energy travel at the same speed, their capabilities are different. It takes longer for a laser to fire, and the beam must reside on the target long enough to destroy it. Although firing a laser is far less expensive than a missile, the effect is the same: one laser shot (hopefully) equals one dead drone (or in recent examples, a few. In contrast, HPM fires in less than a second, has a deep magazine (i.e., the ability to fire many times), and can simultaneously destroy or degrade multiple targets.

Although most HPM systems currently use traveling waves to amplifiers to deliver the necessary massive amounts of radiated power, GaN technology has advanced to the point where it’s become a viable alternative. The first company to break the mold is Epirus, whose Leonidas system uses GaN-based RF power amplifiers to generate the RF power in an active phased array. While tubed-based HPM technologies can be the size of a shipping container, Leonidas can fit in the backup of a pickup truck.

The Transition to 6G

As 5G networks continue to roll out globally, the focus will shift towards developing 6G, which aims to provide data transfer speeds 10 to 100 times faster than 5G, with latency as low as 1 ms. This will open doors for remote surgery, immersive gaming, and emerging applications operating at higher frequencies into the terahertz range. It will also enable ultra-high-speed wireless communication and support for new applications such as augmented reality (AR) and virtual reality (VR) on a larger scale.

6G’s higher frequencies will also unlock new possibilities in sensing and imaging. From high-resolution medical scans to real-time environmental monitoring, 6G-powered sensors will gather vast amounts of data, enabling better disease diagnosis, precision agriculture, and improved disaster response. And, of course, AI will also play a central role here.

Quantum Computing

While quantum computing and microwave technology might seem worlds apart, they have a shared history. In fact, quantum computing and microwave engineering share a common ancestor in the pioneering work that led to the development of radar in the 1940s. While quantum computing has many years to go before it becomes fully realized, once that happens, its effect on the microwave industry will be immense because quantum systems require a diverse array of microwave components, from signal sources to pulse generators, coaxial cables and connectors, RF power amplifiers, mixers, isolators and circulators, attenuators, and filters.

The superconducting type is one of the most promising and widely researched qubits in quantum computing. In superconducting quantum computers, microwave pulses implement quantum gates, which are the basic operations that manipulate qubits. The precision and coherence of these microwave pulses are critical for the accuracy of quantum computations.

Microwave signals are also essential for reading out the state of qubits in some quantum computing architectures. The qubit state affects the phase and amplitude of the microwave signal, allowing for the determination of the qubit’s state. Microwave technology can also facilitate the coupling between qubits, enabling them to interact and become entangled.

In addition, microwave energy can act as a quantum bus, transferring quantum information between qubits in a quantum processor. As superconducting qubits operate at temperatures near absolute zero, there will be an increasing need for microwave components that can operate at these temperatures. Finally, microwave technology is used in cooling systems like dilution refrigerators, essential for maintaining these low-temperature environments.

In Conclusion

The applications I’ve described here are just a few of the many exciting developments that will be taking place this year and throughout the rest of the decade. It’s a great time to be a microwave engineer.