A self-contained adaptive antenna tuner for mobile phones: Featuring a self-learning calibration procedure

Mobile phones are continually being required to operate in more frequency bands whilst accommodating an increasing number of communication protocols. However, the space within the phone allocated to the antenna(s) is not increasing: on the contrary, it is tending to decrease due to the demand for thinner devices with screens that occupy a larger proportion of the phone´s surface. Further, the introduction of Long Term Evolution (LTE) makes it mandatory to accommodate two antennas for Multiple Input Multiple Output (MIMO) operation. Since it is well-known that antenna size and bandwidth are inversely related to each other, it is becoming increasingly difficult to design structures that perform well over the bands required.