Multi-Band Base Station Antennas

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Berenice Palmer
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1 Multi-Band Base Station Antennas Antenna Systems 215 November 5-6 Las Vegas, NV Igor Timofeev Senior Principal Engineer 1

Agenda Introduction to Multi-Band (MB) Antennas History, Evolution, and Challenges Part 1 - Ways to Mitigate Performance Degradation Nesting, Cloaking,

2 Agenda Introduction to Multi-Band (MB) Antennas History, Evolution, and Challenges Part 1 - Ways to Mitigate Performance Degradation Nesting, Cloaking, Filtering, and Choking Part 2 - Practical Examples of Multi-Band (MB) BSA Part 3 - Multi-Band/Multi-Beam (MBMB) BSA Butler Matrix, Luneburg lens, Cylindrical Lens 2

3 Introduction to Multi-Band (MB) Antennas: History, Evolution, and Challenges 3

BSA are different from Traditional MB Phased Arrays Zaslonradar: 64 L-band & 17 X-band radiators and phase shifters Examples of traditional multi-band phased arrays (Late 7s)

Also, because of PIM requirements, electronic phase shifters cannot be employed only electromechanical PS are used (with motors).

4 BSA are different from Traditional MB Phased Arrays Zaslonradar: 64 L-band & 17 X-band radiators and phase shifters Examples of traditional multi-band phased arrays (Late 7s) S-3 radar: 1+ radiators of different bands MIG31 In contrast with radar systems, BSA have fewer elements dozens, not thousands. Also, because of PIM requirements, electronic phase shifters cannot be employed only electromechanical PS are used (with motors). Beam scanning/tilting is performing in only one (elevation) plane. In azimuth, BSA should have the same beamwidthin all bands (85, 65, 45⁰ are standard) CommScopeis the world leader in design and manufacturing of Multi-Broad Band (MBB) BSA. 4

99GHz) (~1% LB, ~1% HB), 2 motors inside 12 ports: (4x.7-.96 + 8x1.7-2.

5 BSA: Evolution from Narrow-Band to Multi-Broad Band (MBB) 7 MHz 8 MHz Low band (LB) (< 1 GHz) Y2: 1% of BSA are MB Y215: 7% of BSA are MB or MBB PCS AWS 23 MHz 26 MHz High band (HB) (> 1 GHz) 4 ports: (2x MHz + 2x GHz) (~1% LB, ~1% HB), 2 motors inside 12 ports: (4x x GHz) (33% LB, 45% HB), 6 motors inside One multi-broadband BSA can replace up to 12 single band antennas Instead of jungle on the roof, there is jungle inside antenna 5

Challenges of Multi-Broad Band (MBB) Antennas Coupling / blockage between elements could cause pattern distortion and degradation of RL, isolation and

receive band) - AWS1/3 combined with 7 results in 3rd order PIM hits in the 7 band.

6 Challenges of Multi-Broad Band (MBB) Antennas Coupling / blockage between elements could cause pattern distortion and degradation of RL, isolation and gain. x x X x x x x X x x Grating lobes / parasitic lobes Asymmetry of Az pattern (squint, F/B) MBB increases potential harmful PIM (PIM that falls in the receive band) - AWS1/3 combined with 7 results in 3rd order PIM hits in the 7 band. - Download CommScope PIM calculator (see link below*) The goal of MBB design is minimize these performance degradations. * 6

7 Part 1 -Ways to Mitigate Performance Degradation: Nesting, Cloaking, Filtering, and Choking 7

8 Nesting: HB is nested inside LB US Patent , 74571, , For all cases below, the goal is to obtain 65⁰ Azbeam in all bands with minimal antenna width. With nesting, it is difficult to obtain UWB HB operation ( GHz is OK, is challenging). LB MAR LB Microstrip Annular Ring (MAR) HB1 ( GHz) HB2 ( GHz) Directors are moving the HB center of radiation higher and shaping the HB radiation pattern LB circular-type folded dipole array Box-type HB radiator 8

9 Filters / Chokes /Traps in LB dipole: Trade-off Between HB Performance and LB Return Loss Printed low-pass filter LB current λ/4 chokes HB current Chokes/filters improve Azbeam stability across the band but could degrade LB RL 9

10 Cloaking of LB dipole Trade-off Between HB cloaking and LB Return Loss Dk=4.4 Cu pattern Test results of LB dipole w/o covered free space Prof. Andrea Alu, UTA 1

11 Part 2 -Practical Examples of Multi-Band (MB) Base Station Antenna (BSA) 11

2-Band BSA with 85⁰ Az Beamwidth DBXRH-8585C-VTM (US Patent 753852, 7639198) Frequency Band, MHz 698 86 86 896 87 96 171 188 185 199 192 218 Gain, dbi 15.1 15. 16.2 17. 16.7 17.

12 2-Band BSA with 85⁰ Az Beamwidth DBXRH-8585C-VTM (US Patent , ) Frequency Band, MHz Gain, dbi Beamwidth, Horizontal, degrees Beamwidth, Vertical, degrees LB element HB and LB elements are placed in one layer to minimize mutual distortions and achieve very stable Az beamwidth over both wide frequency bands Beam Tilt, degrees USLS (First Lobe), db Front-to-Back Ratio at 18, db CPR at Boresight, db CPR at Sector, db Isolation, db Isolation, Intersystem, db VSWR Return Loss, db PIM, 3rd Order, 2 x 2 W, dbc Input Power per Port, maximum, watts Polarization ±45 ±45 ±45 ±45 ±45 ±45 Impedance 5 ohm 5 ohm 5 ohm 5 ohm 5 ohm 5 ohm 12

2-Band BSA with 45⁰ Az Beamwidth US patent 8,58,424 LB elevation pattern, tilt 16⁰ -9-8 -11-7 -12-6 -13-5 -5-14 -4-15 -15-3 -16-25 -3-17 -35 18-4 17 1 9xHB elements with 5 directors on each HB

13 2-Band BSA with 45⁰ Az Beamwidth US patent 8,58,424 LB elevation pattern, tilt 16⁰ xHB elements with 5 directors on each HB elevation pattern, tilt 1⁰ LB azimuth pattern, tilt 16⁰ HB azimuth pattern, tilt 1⁰ Sector power ratio < 3% in both bands (SPR is the most important for LTE)

14 Tri-pole: Solution for LTE MBB BSA US patent 9777 Currents distribution 79 96MHz tri-pole RL, Isoand Azpattern, 79-96MHz 69 96MHz Elephant Ear tri-pole 14

Independent tilt for high bands and single tilt for low bands

Independent tilt for high bands and single tilt for low bands Electrical Specifications 8-port sector antenna, 2x 698 787, 2x 824-894 and 4x 1695 2360 MHz, 65 HPBW, 3x RET and low bands have diplexers Interleaved dipole technology providing for attractive, low wind