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A Tri-Band Shared-Aperture Base Station Antenna Array Covering 5G Mid-Band and 6G Centimetric Wave Band

Shang-Yi Sun, Hai-Han Sun, Can Ding, Y. Jay Guo

TL;DR

This paper addresses cross-band scattering and coupling in a tri-band shared-aperture base-station antenna array for 5G mid-band and 6G centimetric bands. It introduces a CMA-guided segmented spiral LB radiator to suppress scattering across a wide range and uses serial resonators in the LB balun to restore impedance matching, yielding LB operation over $3.05$–$4.68$ GHz. MB/HB elements employ planar magnetoelectric dipoles to avoid common-mode resonances and maintain undistorted patterns with isolation $>20$ dB across bands. Measured results align with simulations, showing broad coverage across LB/MB/HB and scattering/coupling suppression (4.7–21.5 GHz RCS reduction) with practical beam-scanning capabilities, supporting 6G base-station viability.

Abstract

This work proposes a tri-band shared-aperture antenna array with three wide bands, covering the 5G mid-band and the 6G centimetric band, which is a promising candidate for future 6G base station antennas. The challenge of suppressing interferences, including scattering and coupling, in the tri-band array is holistically addressed across wide bands. Guided by characteristic mode analysis (CMA), a segmented spiral radiator is efficiently developed to mitigate scattering and coupling at high frequencies while preserving radiation performance at low frequencies. Compared to a conventional tube radiator, the proposed spiral exhibits a reduced radar cross-section (RCS) over an ultra-wide range of 4.7-21.5 GHz (128.2%). With the aid of serial resonators, impedance matching of the segmented-spiral-based dipole antenna is achieved across the low band (LB) of 3.05-4.68 GHz (42.2%), spanning the 5G band 3.3-4.2 GHz. Moreover, suppressors are placed near the LB ports to further reduce the cross-band coupling. Middle band (MB) and high band (HB) antennas operate in 6.2-10.0 GHz (46.9%) and 10.0-15.6 GHz (43.8%), respectively, collectively covering the anticipated 5G-Advanced and 6G centimetric band of 6.425-15.35 GHz. Both the MB and HB antennas employ a planar magnetoelectric (ME) dipole structure, which prevents common-mode resonances in the LB and MB, and mitigates the scattering from the MB antenna in the HB. In this tri-band array, radiation patterns remain undistorted across the LB, MB, and HB, and the isolation between any two ports exceeds 20 dB over all three bands.

A Tri-Band Shared-Aperture Base Station Antenna Array Covering 5G Mid-Band and 6G Centimetric Wave Band

TL;DR

This paper addresses cross-band scattering and coupling in a tri-band shared-aperture base-station antenna array for 5G mid-band and 6G centimetric bands. It introduces a CMA-guided segmented spiral LB radiator to suppress scattering across a wide range and uses serial resonators in the LB balun to restore impedance matching, yielding LB operation over – GHz. MB/HB elements employ planar magnetoelectric dipoles to avoid common-mode resonances and maintain undistorted patterns with isolation dB across bands. Measured results align with simulations, showing broad coverage across LB/MB/HB and scattering/coupling suppression (4.7–21.5 GHz RCS reduction) with practical beam-scanning capabilities, supporting 6G base-station viability.

Abstract

This work proposes a tri-band shared-aperture antenna array with three wide bands, covering the 5G mid-band and the 6G centimetric band, which is a promising candidate for future 6G base station antennas. The challenge of suppressing interferences, including scattering and coupling, in the tri-band array is holistically addressed across wide bands. Guided by characteristic mode analysis (CMA), a segmented spiral radiator is efficiently developed to mitigate scattering and coupling at high frequencies while preserving radiation performance at low frequencies. Compared to a conventional tube radiator, the proposed spiral exhibits a reduced radar cross-section (RCS) over an ultra-wide range of 4.7-21.5 GHz (128.2%). With the aid of serial resonators, impedance matching of the segmented-spiral-based dipole antenna is achieved across the low band (LB) of 3.05-4.68 GHz (42.2%), spanning the 5G band 3.3-4.2 GHz. Moreover, suppressors are placed near the LB ports to further reduce the cross-band coupling. Middle band (MB) and high band (HB) antennas operate in 6.2-10.0 GHz (46.9%) and 10.0-15.6 GHz (43.8%), respectively, collectively covering the anticipated 5G-Advanced and 6G centimetric band of 6.425-15.35 GHz. Both the MB and HB antennas employ a planar magnetoelectric (ME) dipole structure, which prevents common-mode resonances in the LB and MB, and mitigates the scattering from the MB antenna in the HB. In this tri-band array, radiation patterns remain undistorted across the LB, MB, and HB, and the isolation between any two ports exceeds 20 dB over all three bands.

Paper Structure

This paper contains 11 sections, 29 figures, 2 tables.

Table of Contents

  1. Introduction
  2. LB Antenna Design
  3. LB Radiator Design Guided by Characteristic Mode Analysis (CMA)
  4. LB Balun Design for Impedance Matching
  5. MB and HB Antenna Design
  6. Holistic Suppression of Scattering and Coupling in The Tri-Band Array
  7. Results and Discussions
  8. Experiment Results
  9. Beam Scanning Performance
  10. Comparison and Discussion
  11. Conclusion

Figures (29)

  • Figure 1: Configuration of the developed tri-band antenna array.
  • Figure 2: (a) Geometry of the tube and even spiral, (b) |MWC| of the tube and even spiral, and (c) modal E-field distribution of Mode e2 and Mode e3.
  • Figure 3: (a) Geometry of the segmented spiral, (b) |MWC| of the segmented spiral with different width of slots (g), and (c) modal E-field distribution of Mode 2.
  • Figure 4: (a) Monostatic RCSs and (b) total SCSs of the tube, the even spiral, and the segmented spiral.
  • Figure 5: Bistatic RCSs of the tube and the segmented spiral at two sample frequencies.
  • ...and 24 more figures