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Low Cost Ultra-Wideband Millimeter-Wave Phased Arrays

Novak, Markus
http://rave.ohiolink.edu/etdc/view?acc_num=osu1500574802418502

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Many high performance wireless applications continue to be integrated onto increasingly small platforms, such as satellites, UAVs, and handheld devices. Lowprofile and ultra-wideband antenna arrays have emerged as a potential solution, by allowing many disparate functions to be consolidated into a shared, multi-functional aperture. Simultaneously, the demand for high data rate communications has driven these applications to higher frequencies, with many now exploring the use of the millimeter-wave spectrum. However, existing UWB arrays often utilize complex feed structures which cannot scale to these frequencies. The development of wideband millimeter-wave arrays compatible with low-cost commercial fabrication processes is critical to enabling these small and highly connected platforms. Tightly Coupled Arrays are one family of low-profile and wideband arrays which have demonstrated superior bandwidth and wide scanning capability. However, the feed design of these arrays is limited to operation below 5 GHz, and suffers from reduced efficiency when scanning. In this work, the feed is modified to improve efficiency by eliminating a Wilkinson power divider, and mitigating the resultant cavity resonances with the application of shorting pins. Likewise, strenuous fabrication requirements are relaxed, allowing fabrication at higher frequencies. This effort is approached initially through the intermediate frequencies in the X-, Ku- and Ka-bands, and is demonstrated to allow the new design to scale up 49 GHz. An 8x8 prototype operating over 3.5–18.5 GHz is fabricated and measured to validate the design. Infinite array simulations show VSWR < 2 across this band at broadside, with scanning to ±45deg in the H-plane (VSWR < 2.6) and as far 70deg in E-plane (VSWR < 2). At millimeter-wave frequencies, planar co-fabrication of the entire array is critical to achieving repeatable fabrication, by eliminating the need for complex assembly at such small scales. Simultaneously, compatibility with low-cost PCB processes enables the potential for large scale applicability. The limitations of PCB fabrication are discussed, and a planarized balun consisting of only three vias and two metal layers is developed. The design is shown to operate across 24–72 GHz, with VSWR < 2.2 at broadside, and VSWR < 3 for ±45deg scans in the E- and H-planes. The design is validated by fabrication of 3x3 and 5x5 prototype arrays through a commercial PCB vendor. Measurements of the 3x3 array show close agreement with simulations. Finally, we develop a novel measurement technique, necessary for accurate characterization of antennas at or near Millimeter-wave frequencies. This comprises a post-processing algorithm which serves to compensate the measured phase response of the array for otherwise undetectable, millimeter-scale movements occurring during sequential measurements. This is developed through a mathematical model, and is verified through measurements at Ku band (18 GHz).
John Volakis (Advisor)
Robert Burkholder (Committee Member)
Kubilay Sertel (Committee Member)
164 p.
Electrical Engineering; Electromagnetics; Electromagnetism
millimeter-wave; phased array; PCB; printed circuit board; antenna; ultra-wideband; beamforming; smart antenna; 5G; ISM; wideband; broadband; low cost

Recommended Citations

Citations

  • Novak, M. (2017). Low Cost Ultra-Wideband Millimeter-Wave Phased Arrays [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500574802418502

    APA Style (7th edition)

  • Novak, Markus. Low Cost Ultra-Wideband Millimeter-Wave Phased Arrays. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1500574802418502.

    MLA Style (8th edition)

  • Novak, Markus. "Low Cost Ultra-Wideband Millimeter-Wave Phased Arrays." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500574802418502

    Chicago Manual of Style (17th edition)

osu1500574802418502
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This open access ETD is published by The Ohio State University and OhioLINK.