Antennas for cellular base stations — challenges, trends - ARTISAN

43 Pages·2014·2.35 MB·English

Antennas for cellular base stations
— challenges, trends and constraints —
by Jan Hesselbarth, University of Stuttgart
FP7–A meeting, Belfast, January 30, 2014
RTISAN
outline:
- choice of frequency
- antenna radiator types and characteristics
- macro sector antennas
- antennas for in-buiding and in-cabin systems
- wireless backhaul
- what‘s next
< 1 >
January 30, 2014 Jan Hesselbarth
Antennas to provide coverage, throughput, adaptivity
Different requirements for frequency, pattern, adaptivity, size, cost etc.
macro cell
mm-wave mesh
backhaul
Gbit
Gbit
hotspot
Gbit
hotspot
hotspot
micro cell
< 2 >
January 30, 2014 Jan Hesselbarth
outline:
- choice of frequency
- antenna radiator types and characteristics
- macro sector antennas
- antennas for in-buiding and in-cabin systems
- wireless backhaul
- what‘s next
< 3 >
January 30, 2014 Jan Hesselbarth
Choice of frequency
Criteria for mobile cellular:
antenna size, path loss, diffraction, bandwidth, Doppler
low frequency cellular: high frequency cellular:
- low path loss / large cells - high path loss / small cells
- strong diffraction - weak diffraction
- small Doppler shift - large Doppler shift
- small bandwidth - larger bandwidth
- large antennas - smaller antennas
(cid:198) for coverage and mobility (cid:198) for increased throughput
(cid:198) small throughput in rather small cells
(450 MHz) & 700 – 1000 MHz 1700 – 2600 MHz
Example: „NMT“ network in Skandinavia at 450 MHz: 25 km cell radius,
few users (cid:198) congested in some cities as early as 1983
< 4 >
January 30, 2014 Jan Hesselbarth
Choice of frequency
Criteria for wireless backhaul:
path loss, bandwidth, atmospheric attenuation, licensing scheme
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< 5 >
January 30, 2014 Jan Hesselbarth
Choice of frequency
Criteria for wireless backhaul:
path loss, bandwidth, atmospheric attenuation, licensing scheme
(cid:198) long-distance hops (>10km) with
raher low capacity at 6…20 GHz
. dish diameter ~ 1…2 m
(cid:198) medium-distance hops (3…10km) with
high capacity (~ 100 Mbps) at 28…44 GHz
. dish diameter ~ 0.6 m
(cid:198) shortest-distance hops (<1km) with
multi-GBps capacity at 60 GHz
. dish diameter ~ 0.3m
(cid:198) short-distance hops (<2km) with
multi-GBps capacity at 71…86 GHz
. dish diameter ~ 0.3m
< 6 >
January 30, 2014 Jan Hesselbarth
outline:
- choice of frequency
- antenna radiator types and characteristics
- macro sector antennas
- antennas for in-buiding and in-cabin systems
- wireless backhaul
- what‘s next
< 7 >
January 30, 2014 Jan Hesselbarth
Antenna radiator types and characteristics
For most antennas with sectorial pattern (not: omnidirectional ones),
a groundplane provides suppression of backward radiation and is used
for mounting purposes.
Radiators with groundplane:
patch dipole over ground backed slot
° °
… all similar in gain (5…9 dBi) and in beamwidth (90 …140 )
< 8 >
January 30, 2014 Jan Hesselbarth
Antenna radiator types and characteristics
- backed slot antennas: severe problems with bandwidth
(cid:198) no relevant use
- patch antennas: reasonable bandwidth requires very thick dielectric or
stacked patches;
efficiency and cost and weight requirements lead to
mechanically tricky air dielectric
(cid:198) limited use
example: thick air dielectric patch
(bandwidth~8%@|S |< –10dB)
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< 9 >
January 30, 2014 Jan Hesselbarth
Antenna radiator types and characteristics
- patch antennas:
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example: air dielectric stacked patch 5
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< 10 >
January 30, 2014 Jan Hesselbarth