Professor Wu Ke-li, a professor in the Department of Electronic Engineering from the Chinese University of Hong Kong (CUHK’s) and his graduate students, Zhao Luyu have discovered a way of counteracting the interference that that hinders the function of the phone due to the electromagnetic waves that are picked up by several antennas working in the frequencies very close together or even overlapping each other by a passive circuit. The researchers used some of the power emitting from the phone’s transformers to “eat up” the opposite signal that creates the unwanted interference. Instead of blocking a signal – the current approach – Professor Wu’s strategy turns the signal on itself, creating a negative path for the same amount of signal to cancel the interference from the air.
Perfecting smart-phone service is bound to be a key market. Last year, smartphone sales outdid sales of regular phones for the first time, with 968 million smartphones sold, 54 per cent of the global mobile-phone total, according to the consulting group Gartner, and an increase of 54 per cent over the previous year. For example, if you’re using an iPhone, Apple’s operating system that has a distinctive pattern of its own. You may not notice it, but the phone will not be downloading data while you are talking. That’s because the two antennas involved are separated, with one blocked from the other when they are operating. Likewise the current smartphones in the market has around seven antennas, if not more. Each generation of phone and system – 3G, 4G, WiFi, Bluetooth – adds to the phone’s complexity.
But in a facility that gives a reading which appears as if a mobile-phone signal goes on forever surrounded by foam cones, antennas, a circle of sensors and foam pyramids that are designed to absorb any electromagnetic waves sent out of them, Prof. Wu Ke-li demonstrated an insights that gives us a glimpse of the future for mobile-phone use, and how we interact with each other. Through a better understanding of the antennas in a smart phone, Professor Wu hopes to improve our way of communicating with each other.
Earlier in the research, it was Professor Wu’s graduate student Zhao Luyu who first noticed the ability to decouple the signals using a simple network. “At first I didn’t believe it happened,” Zhao recalls, and wasn’t too sure of its significance. Professor Wu drew on his years of experience in both the corporate world and academia to realize how significant the discovery could be for smart phone makers. “This is a very well-known outstanding problem in the industry,” Professor Wu says. “We can reduce this interference by hundreds times.”
Professor Wu wants to figure out how his research can be used in smart phones. One goal is to be able to mass-produce these already-tiny components – Professor Wu’s group has developed the component in a multilayer ceramic part that is only 1 cubic millimeter – in even-smaller sizes.
Professor Wu is the director of the lab in the only facility of its kind on an academic campus in the world, a radio-frequency radiation research lab, which opened at CUHK in 2006. He hopes that the same results can lead to the formation of a spin-off company that fosters the technology for commercial use. Already, the University holds the intellectual property to the now-patented decoupling technology. “At this stage, it is just a start,” Professor Wu says. “We can apply this new technology to various interference problems in a smart phone and wireless base stations, where the interference between co-existing systems in close frequency bands can be reduced by thousands time.”
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