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Tightly Coupled Dipole Array with Integrated Phase Shifters for Millimeter-Wave Connectivity

Abumunshar, Anas Jawad
http://rave.ohiolink.edu/etdc/view?acc_num=osu1491172877293751

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Advanced satellite communications (SATCOM) applications and multifunctional apertures at Ka-band have created a growing interest for compact, agile, beam scanning, wideband antennas. Phased arrays are of particular interest as they offer beam-steering agility, lower profile and much wider bandwidth compared to conventional mechanical beam steering techniques that are bulky, introduce mechanical noise, and quite slow in steering the beam. Recently introduced tightly coupled dipole arrays (TCDAs) achieve ultra-wide bandwidth performance while having extremely low profiles. However, the size, weight, loss, and complexity of the feed network still make such front ends impractical for many applications. In addition, scaling the TCDA to a higher frequency bands, such as Ka-band, creates issues that have never been addressed before. Most importantly, fabrication limitations arise due to size reduction and material loss at increased frequencies must be addressed in the design. The development of low-cost, simple, lightweight and low-loss wideband phased arrays at Ka-band is critical to improve the capabilities of small platforms such as wireless sensors and unmanned aerial vehicles. This work represents a novel TCDA at Ka-band and addresses the following challenges: 1) An accurate equivalent circuit for the TCDA unit cell at Ka-band; 2) Practical realization of the TCDA at Ka-band; 3) Size, weight, and power (SWAP) performance, and 4) The complexity of the feeding network. To address these challenges, we first introduce TCDA phased array designs using vertically oriented dipoles that can be practically implemented using conventional printed circuit board techniques. The coupling between adjacent elements is used to significantly increase bandwidth while keeping the overall height of the array above the ground plane. To save time in the design process, a simple circuit model is used initially to extract the design parameters of the unit cell. We improved the accuracy of the previously published circuit model by adding the model of the feed gap. Full wave simulations are used to validate the circuit model by using Ansoft HFSS software. Furthermore, we co-designed the feeding network with the phased array antenna to achieve lower loss and higher compactness. Up to date, researchers have focused either on phased array design or on feeding network design. They have never addressed the whole system as a single design; therefore, any possible chance of collaboration or simplification between the feeding network and array antenna is diminished. In this work, we reduce the size and loss of phased array co-designing the arrays with the feeding network. Firstly, we adapted optimum beam forming architecture. This architecture utilizes phase shifter at each unit cell and true time delay at the sub array level. Secondly, we propose to integrate compact phase shifters into each array element of the TCDA using low-loss, low-profile micro-electro mechanical systems (MEMS) technology. This approach is effective in integrating the beam former into the radiating aperture without changing the overall thickness of the array. The phase shifter is designed by using circuit simulation tools such as microwave office and ADS. Subsequently, a full wave simulation of the phase shifter is performed by using Ansoft HFSS. The fabrication challenges that arise due to the smaller features for Ka-band operation, such as the minimum trace width, and the size of the feeding cables and connectors, are addressed by performing the beamforming at the unit cell level, while combining several unit cells through the same connector and feeding cable. The performance of the unit cell with the integrated phase shifter is examined using the full wave simulator Ansoft HFSS. Finally, minimum cost requirements are addressed through the design simplicity, in which, vias, and multi-layer structures are avoided, while the minimum requirements of the affordable PCB fabrication technique are satisfied. The proposed Ka-band TCDA array with integrated MEMS phase shifters is 4.4mm in overall height and covers 18-40GHz continuously with ±45 degrees scan capability.
Kubilay Sertel (Advisor)
Niru K. Nahar (Committee Member)
Fernando L. Teixeira (Committee Member)
James J. Beatty (Committee Member)
209 p.
Electrical Engineering; Electromagnetics; Electromagnetism

Recommended Citations

Citations

  • Abumunshar, A. J. (2017). Tightly Coupled Dipole Array with Integrated Phase Shifters for Millimeter-Wave Connectivity [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1491172877293751

    APA Style (7th edition)

  • Abumunshar, Anas. Tightly Coupled Dipole Array with Integrated Phase Shifters for Millimeter-Wave Connectivity. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1491172877293751.

    MLA Style (8th edition)

  • Abumunshar, Anas. "Tightly Coupled Dipole Array with Integrated Phase Shifters for Millimeter-Wave Connectivity." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1491172877293751

    Chicago Manual of Style (17th edition)

osu1491172877293751
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This open access ETD is published by The Ohio State University and OhioLINK.