Short Range Wireless
5G drives mmWave technology across multiple industries
By Keith Benson, director, amplifier products, Analog Devices T
he technology in today’s world continues to move higher in frequency to solve problems and improve performance. It is these millimeter wave (mmWave) frequencies that offer hope in solving the toughest requirements in many industries such as communications and defence. 5G communication systems benefit from years of research done by defence companies for different applications but similar needs. In telecommunication links, where the need for higher data rates continues to surpass existing techniques, solutions are moving to 28GHz and 39GHz.
The intertwined world of wireless electronics
Industries can often benefit from technology created for a different industry’s application. The microwave oven is generally credited to an engineer working on radars who noticed his lunch was melting during testing. We see this happening today with 5G telecommunications trying to realise the benefits that the defence industry has created with phased array antennas. Satellite communications are undergoing a shift in technology by moving away from geosynchronous equatorial orbit (GEO) or geostationary satellites and exploring low Earth orbit (LEO) satellites that will offer higher data throughput with better coverage of the planet. This idea moves from one or just a few GEO satellites orbiting the Earth to potentially thousands for a given network. There are many operators currently trying to create new LEO constellations for broadband internet use, while many of the companies vying to supply the satellites are the same defence companies that perfected the GEO satellites that are critical for military surveillance and communications.
Higher frequencies enable higher data rates and wider communication bandwidths Every few years, there has been a new wireless standard introduced that defines new protocols to increase data
42 November 2022 Figure 1. Modulation bandwidth centered on carrier frequency
throughput. These improvements in throughput are often correlated to more sophisticated modulation schemes, which can simultaneously transfer multiple pieces of information. As the modulation schemes become more sophisticated, the ability to transfer more data grows. There comes a point where additional increases in modulation complexity do not offer a significant improvement in throughput. A common way to modulate a signal is to spread it over a range of frequencies around a carrier frequency. Another way to improve the throughput is to increase the bandwidth of the modulated signal (FBW) by spreading it over a wider frequency range. In order to continuously increase the amount by which we can spread the signal, we need to increase the carrier frequency (FC) as to not extend below dc. This ability to transmit more data simultaneously by moving to higher frequencies is pushing applications toward mmWave frequencies.
How electronic warfare is impacted by 5G
Military conflicts are increasingly fought electronically, bringing rise to the idea of electronic warfare. One of its key components is radar, which simply transmits a signal and waits for it to return, mapping the field-of-view of the radar. Radar systems have been developed for over 100 years with the key benefit of detecting and mapping objects that are beyond human visibility. This gives the
Components in Electronics
radar operator a considerable advantage over the adversary who does not have radar. For this reason, radar technology has been continually developed.
We now see radar used in daily weather reports, air traffic control, and emerging applications such as in the automotive industry, where radar is used to sense the distance between a car and an object. Traditional low frequency radar systems in UHF and VHF frequencies have been used as early detection radar over very long distances. Fast moving aircraft more often operate at X-band frequencies (8GHz to 12GHz) that benefit from a higher resolution and smaller antennas. Radar systems used in fighter jets to deploy and target missiles often operate at Ka-band frequencies (33GHz to 37GHz). There is increased development happening at 94GHz for guided munitions and missiles. There are several benefits in moving to higher frequencies for radar systems and we can see the benefits by looking at the range resolution and angular resolution that help to characterize the ability to resolve an object. The first benefit of moving to higher frequencies is that the size of the antenna shrinks to obtain a given angular resolution, which is the key to fitting into a small munition. Another way to view it is that the angular resolution increases at higher frequencies for a given antenna size. The range resolution of the radar is proportional to the modulation bandwidth and, as previously discussed, improves at
higher frequencies. As applications need higher resolution, there is a benefit in moving to higher frequencies. Electronic warfare systems for defence companies have operated between 2GHz to 18GHz, which covers S-, C-, X-, and Ku-band radars. As the range of threats increases, so will the electronics to listen for them, and ultimately counteract them. We can see that 5G equipment operating at 28GHz and 39GHz is close to the existing Ka-band frequencies used for missile guidance. New requirements for electronic warfare systems will extend to cover the 5G frequencies ranging from 24GHz to 44GHz. There will be more electronics available at these frequencies for militaries to consider on the battlefield. The main roles of electronic warfare are to listen for a threat and then jam the threat electronically, while remaining undetected. Since a threat can come from various frequencies, the listening equipment, followed closely by the jamming equipment, need to address wide frequency bands of operation. A key technology that has been used in defence applications for many years has become desirable for 5G telecommunications. Phased array antenna technology is desirable for 5G with several features that the defence industry also finds valuable. Such key attributes include the ability to transmit multiple data streams or radiation patterns. In defence applications, this could allow a fighter jet to track multiple targets at one time, while in 5G telecommunications, it allows them to transmit data to multiple users at one time. Similarly, defence applications desire a beam where the energy is targeted in one direction, providing a low probability of intercept or jamming. Telecommunications benefit from consuming less power dissipation because they are more efficiently able to target the information to the user. Both applications benefit from the ability to reposition the beam almost instantly. There are many additional benefits that both the telecommunications and defence industries will appreciate that make this technology attractive.
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