الفهرس 
Co-Designed Antenna Element for Microwave and Millimeter Wave Frequency BandsOnly 14 pages are availabe for public view
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Abstract
The total number of mobile subscription is constantly increasing in the last few decades. Of course there are continuous updating requirements in each mobile generation and these recent requirements and challenges foster the antenna researchers in different communities to design new flexible antenna systems capable of satisfying these huge demands. The most important problem facing the 5G networks is utilizing higher frequencies than their counterparts used in 4G networks will lead to suffering from higher path losses. Therefore, the coexistence of microwave and millimeter-wave technologies becomes the inevitable trend of future next generation wireless communication systems.
In this thesis, the next generation wireless communications including the transition from 4G to 5G mobile networks are studied and the thesis focuses on the system components such as antennas, filters, filtennas, MIMO antenna elements, and arrays that can be utilized in this 4G/5G mobile applications. Different novel designs are explained, fabricated, and measured for better validation to the design theory and structure analysis for proposed antennas, filters, filtennas, MIMO antennas, and arrays.
This thesis is started by designing a novel dual-band antenna with large frequency ratio in order to support sub-6 GHz and MMW operational frequency bands simultaneously. A perturbation theory is utilized in this design and integrating the microwave element with the MMW element can be viewed as loading the same aperture area with double tuning stubs. The MMW element may be viewed as a parasitic element for tuning the MMW resonating modes since it doesn’t have a separate feed. The important feature of the proposed antenna is that it has a single feeding port and can support dual operating bands with large frequency ratio. Then, we turned ourselves to the design of a new ultra-wideband (UWB) bandstop filter (BSF) in order to achieve sufficient isolation between the microwave and MMW frequency bands.
The thesis includes different novel designs of BSFs in order to separate the 4G (microwave) and 5G (millimeter) wave frequency bands. Also, BSFs can isolate the signals of the sub-6 GHz and 28 GHz gNBs (Next Generation Node B) if it is required to deploy both base stations at the same location. Different methods for designing wideband BSF are presented such as open circuited stubs, single section coupled lines, and three sections coupled lines. In addition, the in-line microstrip coupled line BSF is presented to provide better selectivity and roll-off factor. Most of the proposed BSF structures are symmetric and consequently the even and odd mode analysis method is adopted to analyze the structure. The good agreement between the resuts obtained using different analytical methods (full wave analysis and quasi-static analysis) proves the validation of the proposed analysis and theoretical investigations.
The third contribution is the integration between the presented dual-band antenna with the BSF which are presented in consecutive chapters and a complete integrated filtenna structure is presented. Examples of the presented filtennas are; filtennas based on 3-OCSs BSF, filtennas based on in-line coupled lines besides 3-OCSs BSF, filtennas based on in-line coupled lines besides single section coupled line BSF, and filtennas based on bank of in-line coupled line BSF.
Finally, an interleaved antenna array is presented for mobile base stations and access points while MIMO design is proposed for future mobile smart phone handsets. An interleaved array is formed by inserting 3-MMW elements between 2-filtennas and the design represents a 2-element array at 5.2 GHz and non-uniform 5-element array at 28 GHz. For mobile handsets, 4-port MIMO system is proposed which has the ability to simultaneously operate at the microwave and MMW frequency bands. A tapered slot decoupling mechanism is adopted to enhance the coupling and diversity performance and two MIMO configurations are proposed.
All these designs presented in the thesis are analyzed, fabricated, and measured. Good agreement is found between numerical and experimental results.