Forget about 5G! A new, revolutionary device already opens the door to the 6G wireless network –

PHILADELPHIA – If you’ve ever used a smartphone, streaming device, or other wireless gadget, you’ve experienced the magic of radio frequency (RF) filters firsthand. These unsung heroes sort through the jumbled mess of signals bouncing off the radio waves to tune in to the exact frequencies your device needs, while blocking out all the noise and interference. Now, a revolutionary new filter just one quarter in size could soon open the door to 6G wireless signals!

Penn Engineering researchers explain that as new technologies such as 5G and eventually 6G emerge and the number of wireless bands rapidly increases, the old approach of using separate fixed filters for each channel becomes unsustainable. It’s like you need another security guard to usher you into every room you enter. The complexity and inefficiency would be overwhelming.

That’s why a new, innovative “all-in-line filter” developed by engineers at the University of Pennsylvania could be a game-changer. It is a single miniature filter that can dynamically adjust itself to pass any frequencies while protecting noise. One filter to rule them all, so to speak.

“I hope this will enable the next generation of wireless communications,” says Troy Olsson, associate professor of electrical and systems engineering (ESE) at Penn Engineering and lead author of the new study in Nature communication.

The key lies in an ultra-thin layer of magnetic material called yttrium-iron garnet (YIG). When exposed to a magnetic field, YIG film can generate microscopic waves called magnetostatic waves, which resonate at different frequencies depending on the strength of the applied magnetic field.

It works similarly to how tightening or loosening a guitar string changes the pitch of the vibration. Except in this case, “strings” are created by spin waves rippling through the molecular force fields of magnetized atoms. By carefully manipulating the magnetic field across the YIG film, the frequencies of these magnetostatic waves can be continuously tuned.

One of the toughest challenges was finding a way to generate a tunable magnetic field in an ultra-compact, low-power package suitable for today’s slim mobile devices and internet sensors. Traditional YIG filters often rely on bulky, power-hungry electromagnets the size of a soda can – completely impractical for modern smartphones and wireless equipment.

Penn’s engineers solved this problem with an extremely simple but ingenious magnetic tuning circuit about the size of several AA batteries. It combines a permanent magnet with moving “programmable” magnets that can change the magnetic field pattern on demand using short electrical pulses. But here’s the brilliant part – once the moving magnets align in the desired magnetic state, the circuit uses literally zero power to maintain that magnetic tone.

Their proof-of-concept filter measures just 1.68 cubic centimeters – about the size of a typical small Lego figure. However, this tiny device can tune over an incredibly wide frequency range from 3.4 to 11.1 GHz, covering the entire planned 6G spectrum and beyond in one continuously tunable filter.

“We are currently working from 600 MHz to 6 GHz,” explains Olsson. “This is 5G, 4G, 3G.”

“The FR3 band will most likely be introduced in 6G or Next G networks,” Olsson continues, referring to next-generation cellular networks, “and currently the performance of switch technologies with small filters and low-loss switches in these bands is very limited. Having a filter that can be tuned in these bands means you don’t have to install another 100 filters on your phone with lots of different switches. A filter like the one we created is the most viable route to using the FR3 band.”

But it’s not just about the phenomenal tuning range. The filter also features extremely low signal loss of just three to five decibels and excellent rejection of interfering signals in the out-of-frequency bands. These are extremely important features that help prevent wireless crosstalk and maintain signal integrity in crowded environments.

While the most obvious initial use is to improve radio interfaces in smartphones and internet devices, the potential impacts extend far beyond consumer mobile products. This tuning ability could be transformative for cognitive radios, satellite communications, multi-band radar systems and reducing interference at base stations for 5G, 6G and other advanced wireless networks.

“Tunability will be really important,” Olsson continues, “because at higher frequencies there won’t always be a dedicated block of spectrum available just for commercial use.”

Just as quartz crystals enabled the precise timing circuits now embedded in all electronics, these magnetostatic tunable filters could become an essential design element of any system requiring intelligent filtering and frequency flexibility over a wide range of the radio spectrum.

The ability to instantly hop between any wireless frequencies in a small, low-power package opens up new possibilities for designing multi-frequency systems and effectively managing the increasingly crowded and valuable commodity of radio spectrum. Whether you’re streaming Ultra HD video, managing a fleet of autonomous vehicles, or orchestrating future smart city operations, these tunable filters can harmonize the wireless symphony of our hyper-connected world.

StudyFinds Editor Chris Melore contributed to this report.