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Wideband Arrays and Heterodyne Beam Steering Techniques for 5G Communications

Foo, Wei Jian
http://rave.ohiolink.edu/etdc/view?acc_num=osu162032625443105

Abstract Details

2021, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Fifth generation (5G) wireless communication systems are being rolled out to meet the explosive demand for high-speed connectivity, driven by increased proliferation of smart devices and availability of online services. One of the key technologies required in the implementation of these 5G systems are mmWave wideband antenna arrays which can support much increased data bandwidth, beam steering, MIMO signal processing, operation in the 24 GHz to 86 GHz mmWave band and be integrated onto compact smart devices. In this dissertation, we have designed, fabricated and measured a pair of arrays that met these requirements. This pair of orthogonally polarized planar arrays were designed to be fabricated using conventional printed circuit board (PCB) technology, which allows for low-cost fabrication for experimental validation of the designed performance. The parallel polarized topology employs a unique variant of the tightly coupled dipole array (TCDA) that incorporates a balanced antipodal tapered balun as its array element, whereas the perpendicularly polarized array is constructed using a newly developed antenna element known as the connected cascaded monopole antennas (CCMA). These arrays achieve good impedance match with VSWR<2.2 from 24 GHz to 86 GHz, and can scan up to ±30⁰. More importantly, they exhibit realized gain between 5.3 dB to 13.2 dB from 24 GHz to 86 GHz. The arrays were fabricated, and their performance was characterized from 24 GHz to 40 GHz. The 8×1 parallel polarized array, which uses the TCDA with tapered balun (TCDA-TB) as its array element, was also further studied, and was found to have two radiating modes: A forward radiating mode, and an axial radiating mode. By modifying the physical dimensions of the TCDA-TD unit element, the occurrence of the axial mode can be shifted in frequency, or suppressed completely. A new study of the TCDA-TB array using port characteristic mode analysis is presented, which was used to identify that the lowest operating frequency of the array can be decreased by manipulating the shape and length of the edge elements, while maintaining coverage of the mmWave band. The edge elements were subsequently modified to achieve VSWR<2 across the 5G sub-6 GHz band (3.2 GHz – 4.2 GHz), thus a novel antenna array system that covers both 5G bands is obtained. Beam steering is also one of the key enabling technologies of 5G. Here, we present a potentially low-cost beam steering approach known as the heterodyne beam steering (HBS) technique. The HBS technique involves the mixing of a pair of separate tuning frequency signals propagating along counter-directional feed lines to generate the required progressive phase difference at each array element for beam steering. Thus, by only controlling the two tuning frequencies, a linear HBS network (HBSN) can be used to beam steer a linear array of any length. We present formulas deriving the bandwidth requirement of the tuning frequency sources, the receive array schematic. This is done by modifying the one-dimensional (1D) HBS using linear frequency modulation (LFM) signals in place of monotone tuning frequencies, and analyzing the signal distortion due to timing delays inherent in 1D HBS. These developments culminated in the development of the 2D HBS technique, which can theoretically 2D beam steer any N×N array using only three independent frequency sources. This 2D HBS transmit circuit was then designed and fabricated to experimentally demonstrate 2D beam steering on a 4×4 patch array. Our work on wideband mmWave arrays have produced the first hardware to enable operation across the entire mmWave band for both polarizations, while the developments in HBS increases its viability as an alternative beam steering technique for implementation in 5G systems due to its ease of control. As such, these findings contribute to the successful development and implementation of future 5G systems.
Kubilay Sertel (Advisor)
194 p.
Electrical Engineering; Electromagnetics

Recommended Citations

Citations

  • Foo, W. J. (2021). Wideband Arrays and Heterodyne Beam Steering Techniques for 5G Communications [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu162032625443105

    APA Style (7th edition)

  • Foo, Wei Jian. Wideband Arrays and Heterodyne Beam Steering Techniques for 5G Communications. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu162032625443105.

    MLA Style (8th edition)

  • Foo, Wei Jian. "Wideband Arrays and Heterodyne Beam Steering Techniques for 5G Communications." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu162032625443105

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.