Study And Design On Compact High-performance Ultra-wideband Diversity Antennas

With the tremendous growth of modern wireless communications, it becomes the major problem of developing compact high-performance wireless communication devices that how to realize the polarization diversity of multi-antennas in the limited space. Improving the polarization purity of array elements, reducing the mutual coupling and reducing the dependence on the installation of applications are the efficient ways to solve this problem. Thus, it is essential to develop compact high-performance ultra-wideband (UWB) diversity antenna. Design concept is proposed in this dissertation about the compact ultra-wideband diversity antenna which has lower cross-polarization characteristics. The theory and methods are explored about improving the polarization purity to solve the problem of mutual coupling in the antenna elements. Based on studying the ultra-wideband polarization diversity antenna, the dissertation also designs a compact wideband and narrowband combined antenna which has spectrum sensing function. The main content of this dissertation includes:(1) First, the dissertation introduces the concept, basic principles and analysis methods of the ultra-wideband antenna, and reasonably explains the working mechanism of it.(2) Then, based on the theoretical knowledge on UWB antennas, the dissertation studies the coexistence probelm of multiple compact ultra-wideband antennas in the limited space. Designs and analysizes the ultra-wideband polarization diversity antenna, wideband and narrowband combined antenna, both of which obtain gain by using vertical polarization and horizontal polarization. The average isolation between the elements is improved to higher than 30 dB.(3) Finally, a compact ultra-wideband diversity antenna, wideband and narrowband combined antenna are designed by using IE3D. The two antennas are numerically and experimentally studied for their performance.