Broadband and Reconfigurable Filtering Antennas for Next Generation Mobile Wireless Communications Systems
1 online resource (143 pages) : PDF
University of North Carolina at Charlotte
Mobile wireless communications systems, particularly at the base station level, are ever evolving to provide more data with better coverage resulting in continuously evolving antenna technology. From first generation (1G) mobile networks deployed using simple vertically polarized omnidirectional antennas to future fifth generation (5G) networks utilizing advanced dual polarized multibeam antenna solutions, mobile base station antennas have seen rapid development in the last 40 years. Today’sfourth generation (4G) base station antenna systems commonly use multiband, dual polarized antennas where optimal performance is desired in difficult operating environments. Common operating bands for current 4G base station antennas are 698-960 MHz and 1695-2690 MHz where antenna elements covering both bands are usually integrated into a single package. This can make it difficult to achieve desired pattern performance and impedance matching. Furthermore, 600 MHz, 3.5 GHz, and 5 GHz spectrum has been released for mobile base station antennas creating wider bandwidths and more bands in the same radome or collocated under different radomes. Future 5G antenna systems will operate to millimeter wave frequencies (>30 GHz) and deliver data rates much higher than those of today’s mobile networks. Due to the small antenna size for millimeter wave frequencies, many antenna elements can be integrated into a relatively small package enabling high gain, multibeam solutions which will be required to deliver the data rates promised by 5G. Millimeter wave technology is new to the base station antenna industry, and a significant amount of research and development is underway to understand the possibilities and difficulties of millimeter wave use in the mobile wireless realm. Antennas for mobile wireless applications will be forced to integrate 4G and 5G technology into the same package for some installations. As a result, the base station may be forced to cover frequencies as low as 600 MHz while simultaneously covering frequencies as high as 30 GHz or more. Network densification will also be important in the development of 4G and 5G base station antennas. This involves placing many antennas in areas of high data traffic creating a need for low profile antennas withprecise pattern control to minimize sector overlap. Unfortunately, the addition of new spectrum coupled with network densification creates a need for filters to manage interference.Filtering is also an essential part of wireless systems to block unwanted signals that can cause system degradation. Filters can be bulky, expensive, and difficult to implement. Integrating the filter directly into the antenna has tremendous advantages in terms of size, cost, and the ability to control the filter impact on the system. The addition of new spectrum for advanced 4G and 5G systems creates a need for filtering antennas to reject unwanted signals that can degrade the overall system.This dissertation presents the design and analysis of filtering antenna systems to meet the demands of 4G and 5G mobile wireless applications. New and innovative antennas incorporating broadband and narrowband filters are presented to manage interference for tomorrow’s mobile wireless systems.
Weldon, ThomasKakad, YogendraMostafavi, Taghi
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2018.
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