As we know, electromagnetic waves from mobile phones and computers have limited amount of bandwidth available on the spectrum. Thus, engineers have envisioned that enabling wireless devices to send and receive information on the same frequency would be one way to overcome that limitation. But incoming and outgoing waves on the same frequency just typically interfere with each other.

With that dilemma in mind, UCLA electrical engineers have designed a solution. The researchers proved that a circulator sharing the same antenna could enable signals to be sent and received simultaneously. Sending signals on the same frequencies that they are received could essentially double the space on the spectrum available for chips to transfer data.

Previous generations of circulators used magnetic material, which cannot be incorporated into current microchips and doesn’t have enough bandwidth for today’s smartphones and other devices. The UCLA prototype uses coaxial cables to route the electromagnetic waves through non-magnetic material, but the device would likely to be built with silicon-based or other semiconductor materials.

The team established an approach called “sequentially switched delay lines,” which is similar to the way transportation engineers route passenger trains from one track to another, to allow multiple trains to enter and exit train stations at the same time and avoid collisions, even if there are only a few available tracks.

circulator_SSDL Figure 1: Similar to a busy train station, electromagnetic waves of the same frequency carrying information are actively switched onto and off inside a chip.  

The design includes six transmission lines, all of equal lengths, connected by five switches. The switches are turned on and off sequentially to distribute electromagnetic waves and allow simultaneous transmission and reception of data-carrying signals.

Previous studies have demonstrated that signals could be sent and received simultaneously using the same electromagnetic frequency, which modulated the signals. But, according to the researchers, this design is the first one that offers unlimited bandwidth.

The team claims it could easily be incorporated into current chip manufacturing processes and within almost all industry-standard designs. Previous concepts would have required the use of components that don’t align with current industry standards, or have only worked in a narrow band of the spectrum. Yuanxun “Ethan” Wang, an associate professor of electrical engineering at the UCLA Henry Samueli School of Engineering and Applied Science who led the research, said that their circulator works from the lowest of frequencies up to radio frequencies and might even work in the visible light part of the spectrum.

To view UCLA researchers’ “sequentially switched delay lines” in action (mp4 animation), click here. The approach switches incoming and outgoing electromagnetic waves along different but equal-length paths to avoid interference.