Reconfigurable Antenna: Narrowband Frequency Reconfigurable Antenna

Background

As described in Bernhard, J. T. (2007), the idea of reconfigurable antenna has been started in early 1930s. In 1979, a pattern reconfigurable antenna has been designed for satellite communication. The proposed antenna is capable to reconfigure to six different beam angles. A pattern reconfigurable antenna with multi beam reconfiguration for satellite communication is also been reported in Capone, E. & Pelaca, R. (1986). In 1999, a reconfigurable leaky patch antenna using PIN diode has been presented in Chang, B. C. C., Qian, Y., & Itoh, T. (1999). From 1999 until the present day, microstrip antenna has been used as a platform to design reconfigurable antenna.

Instead of multiple or multiband antennas, narrowband reconfigurable antenna offers significant advantages which smaller in size and offers pre-filtering at the receiver. Narrowband reconfiguration is potentially useful for cognitive radio system. Cognitive radio is a system that can change its transmitter parameters based on interaction with it environment which it operates. In general, cognitive radio has the capability to sense an available channel and used to establish communication link. Cognitive radio architecture concepts have been summarized in Haupt, R. L., & Lanagan, M. (2013). This system has been divided to two main categories. The first category is where the system continuously monitors the spectrum while running in parallel with the communication link. A wideband antenna with omni-directional radiation pattern is used for spectrum sensing and a narrowband reconfigurable antenna is used for the communication link. A single wideband antenna can also be used for both sensing and communication. The second category is where spectrum sensing and communication link are sharing a single channel. Threshold mechanism is used to switch between sensing and monitoring. A wideband antenna or narrowband reconfigurable antenna can be used in this type of system. However, the reconfigurable antenna offers pre-filtering in the front end system, which reduces the interference at the receiver.