Antennas and beam-steering arrays for polarization diversity and full-duplex applications
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This thesis presents new designs for polarization diverse dielectric resonator antennas (DRAs) as well as antennas that can offer efficient full-duplex (FD) functionality. Basically, this research effort has been completed to meet the demands of modern tracking systems as well as in-band full-duplex communication systems. For these applications antenna polarization control, compatibility, co-location, and isolation are the important parameters to support these high-performance systems. The first part of the thesis covers the challenges of modern radio frequency (RF) environments where the proposed polarization reconfigurable antennas are introduced. At first, a multi-port DRA is outlined as a possible candidate for the global positioning system (GPS) and the Global Navigation Satellite System (GNSS). To further advance this original design, and in an effort to reduce the size whilst maintaining polarization control, an integrated circuit was also proposed and tested. Advancing from the research work of phase polarization control using DRAs, the second part of the thesis studies other new antennas which are suitable for FD communications. Those antennas offer high isolation which makes the signal recoverable for those FD systems. To advance the state-of-the-art, an H-shaped slot antenna arrangement with parasitic patches and dual-differential feeding was proposed. The antenna architecture was investigated with both external and integrated feed systems and both prototypes offer high isolation levels. The single-element was further integrated into a 1×4 antenna array which was shown to offer similar isolation levels and with the capability to beam steer. Further research included high isolation antennas for operation in the 5G mm-wave band. In particular, a new FD pattern reconfigurable antenna was proposed which can be used in dual-polarized radars and other FD systems. Depending on the input phase excitation, the beam pattern control can be established with sum or difference patterns or both. Also, the antenna concept was further extended into a novel FD antenna array. This array has a similar common and/or differential feeding which can provide sum or difference patterns in the far-field. Also, an external Butler matrix was used to investigate the beam-steering capabilities of the array. These antenna systems also have applications for dual-polarized radars, retro-directive arrays, and other beam-tracking scenarios which require high inter-port isolation.