Multi-band 5G Antenna Designs for Smartphones

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

In the pursuit of increasing data transmission rates, mobile communications have rapidly evolved into the 5G era. With more and more frequency bands being specified and utilized, one of the longstanding challenges in mobile phone antenna design has been to cover multiple communication bands within the limited internal space of a phone. The introduction of Multiple-Input Multiple-Output (MIMO) technology and millimeter-wave (mm-wave) technology, together with the attractive visual appearance of handsets, has presented new challenges for mobile phone antenna design. The first part of this thesis concentrates on frequency-reconfigurable antennas, specifically utilizing lumped components. A full metal-rimmed model serves as a basis in the antenna designs covering hepta-band of 4G and C-band of 5G. A decoupling method of 5G MIMO antennas is also proposed based on the current suppression in a ring slot. Subsequent designs in this part focus on the frequency-reconfigurable antennas in the mm-wave frequency band. Required capacitance is first studied in the frequency band from 24 to 43.5 GHz, and practical antenna design is then implemented with commercially available tunable components, covering a frequency band from 23.2-30.2 GHz with total efficiency larger than -2.5 dB. A novel cluster array concept is introduced in the second part for frequency tunability through the adjustment of feeding weights. Realized gains of antenna arrays are maximized using eigenvalues of electric-field results. The proposed approach can be applied to various antenna designs to improve the spherical coverage in a wide frequency range. For instance, diverse patch and dipole elements, which can be seen as multiple-resonance circuits, are employed to illustrate this concept. The third part presents a dual-polarized end-fire antenna array as a supplement to broadside antennas achieving full spherical coverage required for the 5G mm-wave applications. Multiple resonant modes are generated through the use of a novel stacked antenna with a low profile for vertical polarization. The overlapped bandwidth of the vertical polarization and horizontal polarization ranges from 24 to 43.5 GHz. The methods developed in this thesis achieve the multiple frequency bands for 5G mobile communications. This work contributes to the antenna designs for modern smartphones, incorporating the research between practical applicability and innovative approaches.
Translated title of the contributionMulti-band 5G Antenna Designs for Smartphones
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Viikari, Ville, Supervising Professor
  • Lehtovuori, Anu, Thesis Advisor
  • Ala-Laurinaho, Juha, Thesis Advisor
Publisher
Print ISBNs978-952-64-1629-8
Electronic ISBNs978-952-64-1630-4
Publication statusPublished - 2024
MoE publication typeG5 Doctoral dissertation (article)

Keywords

  • 5G
  • beamforming
  • frequency-reconfigurable
  • mobile phone antennas
  • millimeter-wave
  • Sub-6 GHz

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