Theroratical Study of Fully Printed Magnetically Tunable Reconfigurable Patch Antenna

Due to varying wireless standards in different regions, there is a big desire to have reconfigurable and tunable components which can be tuned to the frequency of interest. At present a single wireless device, such as a mobile phone contains multiple antennas, filters, all of them working at different frequencies. It will be great if an antenna or a filter can be tuned to work at different frequencies, thus the overall number of antennas or filters in a device can be reduced. This control is possible through a magnetic field, if these components are built on a magnetic substrate. Traditional magnetic substrates are expensive that involve complicated fabrication process and operate the material in saturated state making them inefficient. A better approach would be to operate the antenna or any other microwave device in the partially magnetized state. In this work, the authors present the theory and design of a polarization reconfigurable patch antenna with frequency tunablity in the unsaturated state. Operating away from the saturated state can improve the overall efficiency of the RF components. The analytical model is initially verified using a high frequency simulator to predict the antenna performance on a magnetic substrate with normal bias. A low-cost printing technique where the substrate could be realized using magnetic ink is used for the implementation of the antenna. A circular patch antenna working at 6 GHz is used for the validation of the theory. When triggered by an external magnetic field, the as-fabricated antenna shows a maximum tuning range of ~16% and ~5% for the two splitted frequency points. A good match is achieved between the theory, simulations and measurements of the antenna.