In the early 2010s, LightSquared, a startup aiming to revolutionize cellular communications, went bankrupt due to problems preventing its signals from interfering with GPS systems. Now, Penn Engineers have developed an adjustable filter that can prevent interference, even in higher-frequency bands of the electromagnetic spectrum, potentially enabling the next generation of wireless communications. The electromagnetic spectrum is a valuable resource, with only a small fraction suitable for wireless communication, controlled by the FCC. Wireless communication has traditionally used lower-frequency bands, but the FCC has recently made the Frequency Range 3 band available for commercial use, which may be used in future cellular networks.
The new adjustable filter designed by Penn Engineers can selectively filter different frequencies without the need for separate filters, making it particularly useful in higher-frequency bands where dedicated spectrum may not be available. The filter utilizes a unique material called yttrium iron garnet (YIG), which propagates a magnetic spin wave that changes frequency when exposed to a magnetic field. This allows for continuous frequency tuning across a broad frequency band, covering the territory opened up in the FR3 band. The tiny size of the filter, comparable to a quarter, and minimal power requirement make it suitable for integration into mobile phones in the future.
The combination of the novel circuit with extremely thin YIG films micromachined at the Singh Center for Nanotechnology has dramatically reduced the new filter’s power consumption and size compared to previous generations of YIG filters. This advancement in filter technology has the potential to simplify wireless communication devices by requiring fewer filters and saving space. The new filter will be presented at the 2024 IEEE Microwave Theory and Techniques Society International Microwave Symposium in Washington, D.C., showcasing the innovation and potential impact of this technology on the future of wireless communications.
The study was conducted at the University of Pennsylvania School of Engineering and Applied Science and was supported by a grant from the Defense Advanced Research Projects Agency and resources sponsored by the National Science Foundation National Nanotechnology Coordinated Infrastructure Program. The development of the adjustable filter represents a significant advancement in filter technology, potentially paving the way for more efficient and effective wireless communication devices in the future. The ability to tune the filter to various frequencies and its compact size make it a promising solution for addressing interference issues and optimizing the use of the electromagnetic spectrum for wireless communication purposes.