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Millimeter-wave Antenna Arrays with High Efficiency

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2021, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
As the increasing demand for wireless connectivity now causes data traffic congestion at the traditional microwave spectrum, the possibility exists for using untapped millimeter-wave (mmWave) bands to reduce this congestion. While the availability of the 7 GHz unlicensed band (57-64 GHz) makes the 60 GHz band a prime candidate for these next-generation indoor communication systems, difficulties continue to hinder the adoption of mmWave technology. For example, the impaired wave propagation by severe path loss, necessitates the use of high-gain antenna arrays. In addition, given the need of the transmitter and receiver movement and for multi-beam operations, mmWave arrays capable of scanning large angles with high gain are of critical importance. A major shortcoming of current silicon-based millimeter-wave (mmWave) on-chip antennas is the low radiation efficiency (<50%). In this work, we present a novel on-chip antenna array with the radiation efficiency >80% at 60 GHz. The proposed array addresses the issues of on-chip air-suspension using micro-electro-mechanical systems (MEMS) processes, thus elevating the hovering radiating elements on a substrate at the height of 35 μm. The micofabricated SU-8 posts serve as the vertical support, ensuring mechanical stability and monolithic integration. The simulated -10 dB fractional bandwidth of this array is 5.5% or 3.4 GHz at 60 GHz. Further, the designed array is capable of scanning of 55° in the E plane and 58° in the H plane. The non-contact backscattering method is proposed and employed to derive the radiation efficiency from measured Radar Cross-Section (RCS) data. The RCS measurements are performed using a precision 6-axis robotic arm with the spatial repeatability of 20 μm . The measured boresight radiation efficiency is 82% at 60 GHz. The measured peak gain of 9*9 array is 23.3 dBi vs. simulated value of 23.6 dBi. Fundamental enhancement in a suspended array efficiency is achieved by eliminating unwanted radiation in the silicon substrate. Compared to other on-chip integration approaches, the proposed array can be monolithically integrated on a silicon substrate while maintaining high radiation efficiency. In addition to a monolithic on-chip antenna solution, we present a low-cost and high-efficiency antenna array fabricated using a printed circuit board (PCB) process. The optimized via-fed configuration not only enables off-chip antenna measurement in a laboratory environment, but also permits future direct flip-chip integration on a transceiver. Moreover, embedded thin-film resistors are used to fabricate termination and calibration elements on the same board, thus removing associated lossy and bulky external loads and calibration kit. A highly precise robotic antenna measurement system is adopted to measure the performance of the fabricated array. The proposed 5*5 antenna array is matched at 60 GHz with the -10 dB bandwidth of 3.6 GHz (6%). The peak realized gain of the finite 5*5 array is 18.5 dBi, and the measured boresight efficiency is 85%. Further, the maximum scanning volume is 40° in the E plane and 45° in the H plane. Therefore, the proposed array achieves low-cost, high-efficiency, moderate scanning range with a potential for easy on-chip integration for future communication and sensing applications. We present another design of a dual-polarized tightly coupled dipole array with large scanning volume and ultra-wide impedance bandwidth. To improve the scanning volume without exciting surface wave modes, two types of superstrates are evaluated on a finite dual-polarized tightly-coupled dipole array: (1) dielectric superstrate and (2) novel planar frequency selective surface (FSS). The latter architecture is capable of scanning 70° in the E Plane and 65° in the H Plane and shows, on average, 5° scanning improvement to the former. The impedance bandwidth is 5.25:1 (0.8-4.2 GHz) at the broadside (VSWR<2). The bandwidth reduces to 4.3:1 (0.9-3.9 GHz) when maximum scanning angle increases to 65° for the H plane and 70° for the E plane (VSWR<3.2). Therefore, this proposed array is a great candidate for wide-angle wide-band scanning applications covering the entire L and S bands.
Nima Ghalichechian (Advisor)

Recommended Citations

Citations

  • Li, J. (2021). Millimeter-wave Antenna Arrays with High Efficiency [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1608028409318704

    APA Style (7th edition)

  • Li, Jiantong. Millimeter-wave Antenna Arrays with High Efficiency. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1608028409318704.

    MLA Style (8th edition)

  • Li, Jiantong. "Millimeter-wave Antenna Arrays with High Efficiency." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1608028409318704

    Chicago Manual of Style (17th edition)