- Radio Frequency Systems

The Radio Frequency Systems Bulletin
3rd quarter 2005
R o b o t i c t u n i n g — R F f i l t e rs
on the fast-track
Singapore expressway takes 3G underground
Argentine mobile on the move
Rebanding and the RF filtering challenge
3G indoors with Alcatel
The Clear Choice™
Wireless data heads indoors
04 What’s New
Wideband PCS/cellular TMA lifts
wireless data bit-rate
New I-BSA band-selective amplifiers
FM antenna: lightweight and low-cost
RADIAFLEX ‘A’ RAYU AT
optimally tuned
CELLFLEX ‘A’ premium
attenuation
06 Confined Coverage
3G indoors with Alcatel
Robotic tuning—RF filters on
the fast-track
Rebanding and the RF
filtering challenge
IMPRINT
11 RF Conditioning
03 Editorial
Radio Frequency Systems
WorldWideWeb:
http://www.rfsworld.com
16 Regional focus
Argentine mobile on the move
18 In Touch
Particle accelerator gets RFS ‘in-tunnel’
treatment
RFS makes impact with low-impact
in Singapore
Brunei TV goes digital
PREVIEW: Strumming the HAARP
Publisher: Jörg Springer
Executive Editor/Editor Asia Pacific:
Peter Walters
Editor EMAI: Regine Suling
Editor Americas: Ann Polanski
Managing Editor: Allan Alderson
Production Editor: Christian Michatsch,
Regine Krüger
Art Director: Marilu Krallmann, Matthias Schwedt
Authors: Allan Alderson, Dr Ellen Gregory, Regine
Suling, Anita Talberg
Photos: RFS archives, Alcatel, BAE Systems, CERN,
Brendan Edwards, Getty Images, Paul Khoo/Onion
Design, Ann Polanski
Cover photography: Ann Polanski
Cover art: Marilu Krallmann
Print: Print Design, Minden
Layout and Graphics:
inform Advertising, Hannover
Editorial Services:
Relate Technical Communications, Melbourne
2
Trademarks: CELLFLEX®, BDA®, FLEXWELL®,
MicroTenna™, Optimizer®, RADIAFLEX®,
Radio Frequency Systems®, RFS®, RFS CompactLine®,
SlimLine® and The Clear Choice™ are trademarks,
service marks or registered trademarks of Radio
Frequency Systems.
INDEX
Argentine mobile on the move
In the wake of Argentina’s economic lull,
Radio Frequency Systems is helping to haul
the country’s wireless telecommunications
sector onto a new wave of technology,
headed for 3G.
16
6
3G indoors with Alcatel
Alcatel, Orange France and Radio Frequency
Systems band together to deploy a broadband indoor distribution network at Alcatel’s
Paris headquarters.
Robotic tuning—RF filters on
the fast-track
RFS unveils two RF filter production
innovations that take the grind out of
the all-important—but traditionally
laborious—RF filter tuning stage.
11
13
Rebanding and the RF filtering
challenge
Interference problems in the US public safety
communications sector have led to a massive
800-MHz spectrum rebanding project. Yet
interim interference abatement and longterm RF filtering strategies will also prove
integral to the final solution.
Wi re l e s s d a t a h e a d s i n d o o rs
The mood of operators and building-owners
Radio Frequency Systems takes a broader
horizontal layers of a building. This
with respect to in-building wireless coverage
and more pragmatic view. Our opinion
trategy dramatically cuts long-term system
has changed significantly during the early
is that each building, and the wireless
maintenance costs.
part of 2005. The prospect of tapping into
coverage required within each building, is
the growing revenue stream presented by
unique. The wireless distribution solution for
Lastly, the solution must be genuinely
wireless data is clearly behind this change in
each should be as unique as the building
futureproof and truly broadband. Electing to
mood. In-building wireless has come of age.
itself—the solution should be tailored to the
deploy
For much of the past decade, operators’ and
architecture of the building, and the current
solutions—particularly those founded on
building owners’ interest in in-building
and future needs of its occupants. In contrast
narrowband
wireless has waxed and waned. While
to its techno-centric competitors, RFS sets
prove costly in the longer-term. In the
the technical argument for in-building
out to develop ‘end-to-end’ in-building
fast-growing
world
coverage was strong, the business case
solutions that best meet three essential
factoring
capacity
for ‘voice-only’ or ‘voice plus simple data
performance criteria: premium coverage,
‘growth space’ is essential.
services’ was elusive. Without real applica-
capacity and quality of service (QoS);
tions and quantifiable business benefits,
minimal total life-cycle cost; and genuine
No single technology or architecture can
it was difficult to justify the expenditure.
futureproof characteristics.
meet these performance criteria across the
cheap
in
‘ready-to-go’
distribution
of
in-building
systems—will
wireless
and
data,
technology
A further stumbling block has been the issue
broad range of building configurations and
of just how CAPEX/OPEX might be shared
building occupants’ needs. Rather, the
across numerous participating operators.
optimal solution needs to be tailored, and
Dr Klaus-Dieter Mischerikow
Radio Frequency Systems President
EDITORIAL
The launch of powerful wireless data
developed from a mix of current and
technologies—most particularly 3G cellular
emerging technologies. RFS offers just this
and wireless LAN (WLAN)—has changed
Network coverage, capacity and QoS will be
tailored in-building development service.
all this. The ‘natural home’ of such services
the crucial decider in the in-building wireless
Our 50 years of in-building/in-tunnel design
is clearly in-building, especially in the
data world. While the “stand a little closer
and development experience is backed by
commercial sector. Importantly, the ‘neutral
to the window” strategy was adequate in
the market’s broadest mix of futureproof in-
host’ business model—where in-building
‘voice-only’ or ‘voice plus simple 2G data
building technologies—distributed antenna
wireless
services’
systems, broadband feeder solutions, point-
infrastructure
is
owned
and
environments,
the
world
of
managed by a non-operator party, with
high-speed wireless data is far less forgiving.
of-interface
CAPEX and OPEX costs shared across all
A truly seamless broadband experience
extension systems.
participating operators—is fast gaining
across all operational areas of the building
industry acceptance. Shared in-building
will be essential to win over this demanding
Clearly, in-building wireless is set to grow
market.
dramatically in the coming years, under-
infrastructure,
centred
on
broadband
RF combining solutions that support a multi-
solutions,
and
RF-on-fibre
pinned by the emergence of high-speed
band/multi-carrier environment, underpins
Similarly, minimization of the total life-cycle
wireless data services. But in-building
the ‘neutral host’ strategy.
costs of the distribution system will be a
wireless deployment—particularly in the
vital deciding factor. While the reduced
demanding commercial world—will present
CAPEX
major challenges. Success will come down
The
response
from
the
in-building
of
many
solutions
on
offer
technology sector to this recent upsurge
might initially appear attractive, closer
to total system performance, rather than
of interest in in-building wireless has proven
examination of long-term OPEX reveals
specific technologies. RFS has the total
fascinating, to say the least. Many promote
their
a ‘one-size-fits-all’ approach to in-building
in-building
coverage: that a single wireless in-building
founded on the principle of minimizing
technology and architecture will meet the
the
needs of any building.
throughout the system, particularly in the
weaknesses.
To
this
distribution
number
of
active
end,
RFS
systems
solutions
are
solutions to meet this important challenge.
perspective,
experience
components
Klaus-Dieter Mischerikow
and
3
Wi d e b a n d P C S / c e l l u l a r T M A
l i f t s w i re l e s s d a t a b i t - ra t e
Radio Frequency Systems has unveiled an
The new wideband TMA provides carriers
important new addition to the company’s
with higher data subscriber rates without
comprehensive active RF conditioning suite
reducing capacity, by improving base station
—a new low-noise TMA is specifically
receiver sensitivity and enhancing overall
designed for universal mobile telecommu-
cell coverage. It provides a unique dual-band
nications system (UMTS) PCS-band/cellular-
full-duplex amplifier solution for both cellular
band overlay applications. It provides the
and PCS bands. With a nominal gain of 12 dB,
The new TMA supports transmit/receive
essential gain boost required to ensure
the unit is particularly lightweight (less than
bands of 869 to 894 MHz/824 to 849 MHz
optimal subscriber bit-rate in wireless
10 kg (22 lbs)) and compact, making it ideal
on the cellular side, and 1930 to 1990
data applications.
for tower-top mounting.
MHz/1850 to 1910 MHz on the PCS side.
“Network performance will make or break
This multi-function TMA is available in four
For increased reliability, the unit is equipped
carriers in the emerging wireless data
configurations: co-located cellular/PCS with
with a bypass switch in both bands. The
market,” said RFS Director, Marketing and
amplification in both systems, co-located
TMA features a mid-band noise figure of
Technical Services, David Kiesling. “Accurate
cellular/PCS with a bypass on the cellular
less than 1.7-dB on both cellular and PCS
control and management of RF power levels,
bands, PCS-only, and cellular-only. The TMA’s
sides, and a transmit path insertion loss of
antenna beam direction, and most particularly,
dual-duplex configuration enables the use
less than 0.5 dB. Its precision filter roll-off
signal-to-noise ratio will be the critical
of a single feeder for both transmit and
(15 dB/MHz on the cellular side, 5 dB/MHz
differentiators in the wireless data market.
receive paths. Its integrated diplexer obviates
on the PCS side), ensures improved
Our new wideband PCS/cellular TMA is an
the need for an external diplexer at the
transmit-receive
important element in realizing such solutions.”
tower top, thus reducing tower loading.
absolute delay variation in the uplink.
isolation
and
reduces
strong or weak link from outside the building,
4
regardless of what’s behind the amplifier,
WHAT ’S N EW
the RFS I-BSAs provide a great deal of
flexibility in planning and system set-up,”
New I-BSA
band-selective
a m p l i f i e rs
said Lehmann.
For the European and Asian markets, the
I-BSA900-1 has been specifically designed
for global system for mobile communications
(GSM) in the 900 MHz band. Similarly, for
the American and Asian networks, the
I-BSA800-1 is tailored to suit services in the
cellular 800 MHz band (code division multiple
access (CDMA), time division multiple access
At the CeBIT exhibition in March 2005,
Radio Frequency Systems launched two
Communication Systems. Separate gain
(TDMA) and the analogue advanced mobile
new band-selective bi-directional amplifiers
adjustment for uplink and downlink is
phone standard (AMPS)).
designed for the 800 MHz and 900 MHz
achievable while maintaining the same
Allowing
frequency bands. The compact I-BSA800-1
power output in both directions. As a result,
I-BSA800-1 and I-BSA900-1 feature variable
and I-BSA900-1 amplifiers feature finely
the I-BSA is the ideal point-of-interface
frequency
adjustable frequency bandwidth selectivity
(POI) for in-building systems founded on
0.03 MHz to 25 MHz, and 0.2 MHz to
via a unique PC-based configuration software
external antennas.
25 MHz, respectively. “Such fine-tuning is
tool. The uplink/downlink frequency ranges
According to Lehmann, the I-BSAs have
possible just by connecting a laptop to the
supported are 824 to 849 MHz/869 to
been designed to receive and re-transmit
device,” said Lehmann. The user-friendly
894 MHz and 890 to 915 MHz/935 to
signals derived from antennas outside a
programming
960 MHz respectively for the I-BSA800-1
building, and amplify only the selected
authorized access only, for reasons of security
and I-BSA900-1.
bands for in-building distribution. With the
and asset management—provides the ability
“As the new I-BSAs are sub-band selective
RFS I-BSA series providing the building’s
to configure the I-BSA’s frequency bandwidth,
they are the ideal complements to RFS’s
primary POI amplification and band selection,
amplification and gain. Uplink and downlink
broadband I-BDA bi-directional amplifier
localized signal amplification can be provided
gain is adjustable in 2 dB steps between 20 and
family,” said Stefan Lehmann, RFS Area
throughout the building using RFS’s broad-
60 dB, while output power is 22 dBm (in both
Product Manager Wireless Distributed
band I-BDA units. “Whether you have a
uplink and downlink) at maximum gain.
precision
bandwidth
adjustments,
selection
software—which
the
from
allows
FM antenna:
lightweight
and low-cost
The new single-channel CPF-series side-
The CPF-series is also available pre-
mounted FM antenna from Radio Frequency
packaged in multi-element arrays with a
Systems offers a low-cost, lightweight
range of gains, utilizing high-quality RFS
solution for low to medium power
power dividers and distribution cables.
applications in the 87.5 to 108-MHz band.
Powers of up to 20 kW are possible for an
Featuring robust stainless steel construction,
eight-bay antenna array, with gain of up to
the CPF-series is available with single-
6 dBd in each plane.
element power ratings of 500 W (CPF500)
Radome options for the CPF-series include
or 2.5 kW (CPF2500).
a feedpoint radome, or alternatively a
A new incarnation of RFS’s popular ECFM
spherical radome that fully encloses the
antenna, the circularly-polarized, omni-
radiating element for locations when icing
directional CPF-series FM antenna features
is a problem. Other optional components
extended power range and other design
include heating elements and an input
enhancements. In particular, the radiation
tuner for optimizing voltage standing wave
pattern and axial ratio of the side-mounted
ratio (VSWR). The single-channel CPF-series
CPF-series have been enhanced to minimize
FM antenna complements RFS’s existing
tower effects and downward radiation.
828-series of FM broadband panel arrays.
comprehensive bands by shifting the
RAYU158-50JAT cable’s stopband into the
1000 to 1650 MHz range. “Stopbands are
inherent physical properties of radiating
cable,” said Lehmann. “By careful modelling
R A D I A F L E X ‘A’ R AY U AT
optimally tuned
and simulation, we have precision-tuned
the RAYU158-50JAT cable so that the stopband is where we want it—out of the way.”
As with all RFS RADIAFLEX ‘A’ products, the
RAYU158-50JAT
cable
offers
superior
Uniquely low longitudinal attenuation and
two important bands: 800 to 1000 MHz
electrical performance, together with good
coupling loss, resulting in low overall system
and 1700 to 2200 MHz.
bending properties, and can support multiple
loss, characterise Radio Frequency Systems’
From a global perspective, these two bands
communication systems simultaneously. It
new RAYU158-50JAT coaxial cable—the
cover the majority of current commercial
is also available with a flame and fire
latest addition to RFS’s popular RADIAFLEX
in-building/in-tunnel radio services. According
retardant jacket (RAYU158-50JFNAT), or a
‘A’ range of foam-dielectric radiating cable.
to Stefan Lehmann, RFS Area Product
flame/fire retardant and low smoke jacket
Ideal for use in tunnels and metros, the band-
Manager Wireless Distributed Communica-
(RAYU158-50JFLAT), to meet the applicable
selective 1-5/8-inch diameter RAYU158-50JAT
tion Systems, RFS has achieved optimal
International Electrotechnical Commission
radiating cable is optimized for operation in
performance
(IEC) standards.
for
these
popular
and
C E L L F L E X ‘A’ p r e m i u m a t t e n u a t i o n
Radio Frequency Systems has unveiled the
(3G) cellular networks, while retaining ease
“The issue of attenuation is clearly important,
next evolution of its popular CELLFLEX ‘A’
of cable handling, mechanical integrity and
but so too is ensuring that the feeder solution
series high-performance feeder cable—the
current connector inventories.
remains ‘installer-friendly’,” said Chris Adams,
new ‘premium attenuation’ variant. Adding
Available to all global markets in early-June
RFS Global Product Manager Transmission
to the feeder system’s already superior
2005, the new CELLFLEX ‘A’ premium
Lines. “We were well aware of this real-world
new
attenuation series will be available in three
multi-variable situation when we developed
CELLFLEX ‘A’ premium attenuation offers a
popular sizes: 7/8 inch, 1-1/4 inch and
CELLFLEX ‘A’, and have come up with a
further reduction in feeder attenuation up
1-5/8 inch. Attenuation improvements
product that represents the optimal balance
to five percent at 2100 MHz.
achieved at 2100 MHz by these three feeder
in all key performance areas. The new
The CELLFLEX ‘A’ premium attenuation
sizes are 3.3 per cent, 4.1 per cent and 5.0
CELLFLEX ‘A’ premium attenuation variant
variant has been specifically developed to
per cent respectively, adding to the average
provides an important enhancement for our
meet the more demanding attenuation
six per cent attenuation improvement
3G customers, while retaining this all-important
performance requirements of third-generation
already offered by CELLFLEX ‘A’.
feeder system performance balance.”
attenuation
performance,
the
5
The historic building housing
Alcatel’s global headquarters is
located in Paris’s 8th precinct.
3 G i n d o o rs
with
Alcatel
Alcatel, Orange France and Radio
Frequency Systems band together
to deploy a broadband indoor
distribution network at Alcatel’s
Paris headquarters.
Alcatel has unveiled one of Europe’s first
integrated indoor distribution systems—a
solution that encompasses a third-generation
(3G) passive distributed antenna system
(DAS). This broadband distribution network,
6
CONFINED COVERAGE
supplied by Radio Frequency Systems, was
3G wall-to-wall
installed in the historic building housing
The RFS design was developed to meet
Alcatel’s headquarters, located near the
exacting
Champs Elysées in Paris. It will give all
determined by Alcatel. “We were required
employees permanent access to the recently
to provide power levels between five and
launched Orange Intense 3G services.
10 dBm at each antenna connector port
Alcatel developed a solution centred on its
across the two buildings, with each
Evolium™ universal mobile telecommu-
building comprising six office levels and
nications system (UMTS) platform, its
three
field-proven service radio technologies,
Parmentier, RFS Global Program Manager.
with RFS providing the essential in-building
“This was particularly important on floors
RF system. According to Benoît de Corn,
four to six, where we had to deal with
Alcatel’s Director of Mobile Network
cell-to-cell
Services, Alcatel determined the building’s
coverage external to the building.”
RF distribution requirements, working in
A further challenge was that posed by the
close collaboration with cellular operator
historic nature of the building, which—with
Orange France, with RFS evolving this into a
its narrow vertical riser, and small horizontal
complete turnkey broadband RF system
ceiling cavities—presented cable-routing
design. “This is a live demonstration of our
complexities. “The administrator of the
joint capabilities—Alcatel 3G solutions
building was quite strict on the positioning
perfectly completed by RFS products—in
of antennas,” said de Corn. “We had to
partnership
performance
parking
levels,”
interference
specifications
said
from
Philippe
UMTS
in
hide a number of the antennas in lamps
continuation to 3G Paris infrastructure
and specific devices so that they were
already provided to Orange,” said de Corn.
not visible.”
with
Orange.
This
is
A number of the antennas were
hidden in lamps and specific
devices to reduce the visual impact.
The complete broadband solution provided
3G floor-to-floor
by RFS is founded on the company’s
The CELLFLEX ‘A’ system links the building’s
popular high-performance CELLFLEX ‘A’
3G base station (node B) to more than
foam-dielectric feeder cable range. The
40 RFS indoor omni-directional and panel
installation comprises 1200 metres of
antennas located about the building, each
1/2- and 7/8-inch diameter CELLFLEX ‘A’
supporting a broadband 800- to 2500-MHz
cable, and a further 250 metres of 1-1/4-
frequency range. For the upper floors,
inch diameter feeder cable. Boasting an
where minimum power levels are critical for
improvement in attenuation performance
preventing UMTS cell-to-cell interference,
of up to six per cent on conventional
RFS provided four 3G/UMTS bi-directional
feeder technology, the CELLFLEX ‘A’ series
amplifiers (BDA) combined with broadband
has been specifically developed to meet the
duplexers. This unique RFS combination
exacting performance needs of 3G cellular
offers a simple and effective means of
networks.
ensuring adequate UMTS RF power levels in
all indoor locations.
“The entire installation is broadband—
couplers, splitters, antennas, BDAs,” said
Parmentier. Tight project timelines also
proved a challenge. To ensure that the
7
project’s completion coincided with Orange
France’s
mid-December
2004
UMTS
commercial launch, RFS was required to
design, install and commission the system
in just six weeks. “To accomplish this, we
drew on our global resources: system
design and cable from Germany, antennas
from China and couplers from Australia!”
said Parmentier.
The system was tested during and after
installation, and has been ‘road-tested’ by
Alcatel HQ residents since its completion in
December 2004. “Everything is performing
even better than expected,” said de
Corn. “In addition, not only is it a largely
passive system—which means low power
consumption and little maintenance—but
it is also completely futureproof.” Services
under consideration to be added to the
Alcatel HQ broadband RF system in the
future include, and are not limited to, the
UMTS enhancement, high-speed downlink
The building’s narrow vertical riser and
small horizontal ceiling cavities
presented cable-routing complexities.
packet access (HSDPA) and digital video
broadcasting-handheld (DVB-H).
RF CONDITIONING
R o b o t i c t u n i n g — R F f i l t e rs
on the fast-track
projects have been running concurrently
at RFS’s two filter production facilities—one
in Connecticut, USA and the other in
RFS unveils two RF filter production innovations that take the grind out of
the all-important—but traditionally laborious—RF filter tuning stage.
Hillerød, Denmark. Using the software
developed by Engst’s team in the US, RFS’s
Danish research team has produced a robot
Throughout the wireless world, there is
Engst, RFS senior engineer, who has
that can handle four filters at a time, being
escalating demand for precision RF filter
been working on the automated
loaded and unloaded as it tunes.
solutions. Largely driven by an increase in
tuning project. “Now that we’ve
“We’ve now had robotic tuners in production
cellular system co-locations, this rise in
succeeded where others have failed,
for over three years—the guys in production
filter demand has focussed attention on
everybody’s all excited.” Engst devel-
depend on it for high volumes,” says Engst.
production
oped the software that allows a robot
The robots have been running in RFS’s
process itself—from order to delivery. In
to analyze a filter and tune it accord-
Connecticut and Hillerød facilities since
response to this throughput challenge,
ingly—in a fraction of the time that
2001, tuning around 150 filters every day
Radio Frequency Systems has developed a
it might take a human tuner.
on those lines with the highest production
streamlining
the
RF
filter
volumes. “The robot takes less then five
number of automated filter manufacturing
systems that set a new standard for filter
Robots for mass tuning
minutes for one filter, where a human
production—systems that make the leap
The purpose of the robot was to accel-
would take 15 minutes—plus a robot doesn’t
from conventional ‘trial and error’ manual
erate the tuning process, primarily
need work breaks,” explains Engst.
filter tuning, to automatic robotic tuning.
for high-volume filter production,
According to Engst, while the robot is
“We wanted to prove that the concept of
while improving product quality and
a breakthrough for high-volume filter
mechanized tuning could work,” says Bill
manufacturing flexibility. Two research
production, there was still a need to develop
11
Bill Engst and the CAT application—
a program that speeds the manual
tuning process.
a more versatile automated tuning option
dealing with smaller batches for specific
applications. Until early-2004, the speed of
the
robot
determined
the
necessary
processing speed of the software. At a safe
speed, the robot could take up to a minute
to execute a tuning stage, moving from one
tuning screw to another, back and forth.
Because of this, the tuning software itself
was not time-critical.
CAT for short runs
Engst’s proposal was to further develop the
tuning software so that it could serve as an
12
RF CONDITIONING
analytical tool for human manual tuning, in
“Initially we’d tested CAT in the lab by
the case of smaller batch runs. “I saw a guy
tuning a 10-pole delay filter—which is quite
tuning by hand for a ‘one-off’ customer
complicated to tune—and it was able to do
and it was taking him so long. That’s when
it easily,” says Engst. This proved the CAT
the light bulb clicked and I realized we
software’s ability to speed the introduction
to
process of new and complex filters into
needed
to
update
the
software
real-time,” says Engst.
commercial
Based on this realization, RFS developed
because the CAT software actually analyzes
computer-aided tuning (CAT) software—a
the filter in order to tune it, it knows
program that allows a human tuner to
instantly if there is a problem with the
expedite
unit, which means no time wasted
the
tuning
process.
“What
production
cycles.
Also,
CAT does is collect data, measure a
troubleshooting.
difference between the data and a
The CAT software was first introduced into
goal, then display this as a bar-graph
the Connecticut production line in March
half
2005, and in conjunction with the robotic
on
a
screen—it
updates
every
second or so,” says Engst.
tuners, allows RFS to provide its customers
The benefit of the CAT software is that it
with fast-tracked deliveries of all filters.
allows RFS to tune its smaller volume and
“The power of these tools is that they
sometimes more-complex filters much
can look into the filters and know
faster, at a lesser investment than the robot,
exactly what’s going on inside,” says
yet retain the consistent reliability. By
Engst,
streamlining the tuning stage, each filter
guesswork—we’re giving our customers
“Which
means
there’s
no
production line has realized increased
exactly what they’ve asked for, every time
throughput as well as a faster and more
and on time.”
flexible response to customers’ orders.
The robotic tuning head takes less than
five minutes for one filter.
The robots running in RFS’s Connecticut
and Hillerød facilities tune up to 150
filters every day.
Rebanding and the RF
filtering challenge
interleaved with public safety channels in
that same spectrum. In addition, the
NPSPAC public safety band is sandwiched
between the high-traffic ESMR band and
the Cellular transmission band, which
Interference problems in the US public safety communications sector
have led to a massive 800-MHz spectrum rebanding project. Yet interim
interference abatement and long-term RF filtering strategies will also
prove integral to the final solution.
starts at 869 MHz. This unfortunate mix
of
disparate
generated
radio
the
technologies
significant
has
interference
problems experienced today.
Two main sources of interference affect the
Radio spectrum allocation in the USA
The
interference
receiver sensitivity of public safety portable
has evolved over the decades in response
problem is the close proximity of public
radios. These are spurious or ‘out-of-band’
to changing needs. As new wireless
safety
assigned
emissions from commercial mobile radio
communications
to commercial mobile radio services—
transmitters, and ‘blocking’ or receiver
emerged, new licenses have been granted,
most
intermodulation.
and each frequency band has been
digital enhanced network (iDEN) systems.
Spurious
divided into thinner and thinner slices of
The current configuration of the US
unwanted transmitter effects—such as
spectrum. Although technologies to eke
800-MHz band is illustrated in Figure 1.
harmonics, intermodulation products and
greater capacity out of this limited resource
The ‘general category’ (transmitting 851
wideband signals that fall outside the
have become more sophisticated, it was
to
transmit band. In the case of iDEN
perhaps inevitable that the heterogeneous
(transmitting 854.75 to 861 MHz) blocks of
transmitters,
allocation of some high-traffic bands would
spectrum are licensed to various specialized
modulated iDEN signal spills outside its
result in headlong collision. A case in point
mobile radio (SMR) services, business
allocated 25-kHz channel and—in the
technologies
have
root
cause
spectrum
notably
854.75
of
the
with
that
high-power
MHz)
and
integrated
‘interleaved’
Figure 1.
Current configuration of
US 800-MHz spectrum.
emissions
the
are
caused
high-power,
by
highly
RF CONDITIONING
absence of any guard band—into the
adjacent channels either side. The result is
desensitization of the receiver for the
adjacent channels, resulting in ineffective
communications.
Receiver intermodulation is the result of the
transmitted interfering signal itself. Put
simply, the raw power of the iDEN signal
overpowers the portable radio receiver,
generating intermodulation products that
is the US 800-MHz band—the latest to be
and industrial land transportation (B/ILT)
can lead to interference, again degrading
targeted by the Federal Communications
systems, some public safety communica-
receiver sensitivity.
Commission
tions and commercial cellular-like services.
Recognizing that action needed to be
The
(FCC)
in
a
high-profile
band
taken in order to meet the critical need
The symptom leading to the FCC’s decision
(transmitting 861 to 866 MHz) is licensed
for robust and highly reliable emergency
to reallocate spectrum within this band is
primarily
cellular-like
communications systems, the FCC has
unacceptable interference problems being
services; while the ‘NPSPAC public safety
adopted a spectrum reallocation plan that
experienced by public safety radio systems.
channels’ are currently transmitting in the
will minimize the impact of commercial
If emergency communications go down,
866 to 869-MHz band.
800-MHz services on public safety radio.
rebanding
project
across
the
nation.
‘Enhanced
to
SMR’
(ESMR)
commercial
Implementation of the ‘Consensus Plan’,
any delays that occur during a search for
alternate means of communication—such
Unfortunate mix
widely supported by public safety groups
as police UHF frequencies, fixed line, or
This boils down to the fact that commercial
across the USA, will achieve the spectral
even
mobile radio channels, dispersed across
separation
frequencies from 851 to 866 MHz, are
technologies (Figure 2). This means the
radio
channel
have tragic consequences.
switching—can
of
generally
incompatible
13
NPSPAC
be
permitted by the spectrum allocations of
result of special dielectric-loaded filter
relocated to the lower end of the band
public
safety
band
will
a particular site. Most sites utilize RF
cavities that provide a high ‘Q’ or quality of
(transmitting 851 to 854 MHz), with all
combining technology in order for multiple
cavity response. The frequency spacing
other public safety channels, non-cellular
channels to be broadcast from a single
between autotune combiner cavities is
SMR and B/ILT services relocated (if neces-
antenna. In practice, each channel enters a
typically 150 kHz.
sary) to 854 to 860 MHz. All commercial
separate resonating chamber (or cavity)
Another victim of interference in the
cellular-like mobile radio services will be
tuned to that channel, and on exiting the
current 800-MHz configuration is the
assigned contiguous spectrum between 862
cavity is coupled to the signals of other
commercial Cellular B’ receive band, which
and 869 MHz, with the spectrum between
channels. The resulting wideband signal
ends at 849 MHz. Base station receivers can
860 and 862 MHz reserved as a 1-MHz
emitted from the combiner typically com-
be affected on the uplink in much the same
expansion band and 1-MHz guard band.
prises six or more channels; this signal is then
manner as the receivers of portable
directed to the antenna for transmission.
radios—in other words, they are subject to
Short-term strategies
As
these
receiver desensitization due to spurious
By the time the staged rebanding project is
combiners have grown more sophisticated,
emissions or blocking from commercial
completed sometime in 2008, it should
and
mobile radio signals close to 851 MHz.
have virtually eliminated the interference
filtering technology within the cavity. In
In such cases, installation of a bandpass
threat to public safety communications.
particular, autotune combiners have been
filter in the interfering downlink to filter
However, there are advanced filtering
deployed at many commercial mobile radio
out-of-band emissions below 851 MHz can
technologies that can be deployed in the
transmission sites. Although the autotune
reduce by more than 50 dB the magnitude
meantime—and in some cases have already
combiner’s
to
of wideband noise received by the affected
been deployed—to minimize interference
continuously monitor and adjust tuning
base station at 849 MHz or below.
in the short-term.
to
carrier
Similarly, installation of a bandpass filter
The ongoing challenge with RF filtering
frequency and environment, the RF filtering
in the uplink of the affected base station
technology
now
has
also
incorporate
primary
accommodate
advanced,
advanced
function
changes
is
in
mitigates the real power of the interferer
falling just outside the affected receive
14
band. Depending on the transmitting
RF CONDITIONING
power of the interfering base station, these
uplink filters need to achieve a minimum
selectivity of up to 50 dB—particularly in
in this band is due to the interleaved
aspect has become increasingly important.
co-location scenarios.
spectrum. Public safety receiver bandpass
For example, the four-channel ‘Quad’
filters must pass all frequencies between
radios used by many iDEN carriers can
Safety spectrum separated
851 to 869 MHz, including those of
provide a combined output of four
The interference situation in the USA after
high-power commercial carriers operating
contiguous 25-kHz channels; this 100-kHz
the rebanding of 800-MHz spectrum will
in the same block of spectrum. The same is
bandwidth corresponds to the bandwidth
be entirely different—and more easily
true for transmitter filtering: all potential
of a typical autotune combiner filtering
controlled. Most significantly, public safety
channels within a certain bandwidth must
cavity. Consequently, each group of four
spectrum will be completely separate from
be passed. It is impossible to limit the
contiguous 25-kHz channels is filtered
that allocated to commercial mobile radio
out-of-band
during
to
services (operating in the ESMR band—
and
Figure 2), virtually eliminating interference
emissions
of
high-power
the
combining
out-of-band
process
signals on a channel-by-channel basis in
minimize
emissions,
this interleaved scenario.
hence interference with public safety
between the two.
It is possible, however, to apply RF filtering
channels. The high filtering performance
In the case of public safety communica-
to groups of contiguous channels, as
achieved by autotune combiners is the
tions, the only remaining interference issue
will be the somewhat unpredictable impact
Figure 2.
Configuration of US 800-MHz spectrum after rebanding.
of transmitter intermodulation. This occurs
when a non-linear combination of two
high-power transmitted signals—such as
an iDEN signal combined with a Cellular
CDMA
signal—generate
out-of-band
emissions that can fall anywhere in the
spectrum. Because of the high transmitted
powers involved, intermodulation products
of a relatively high order may have
sufficient power to interfere with public
Figure 3.
Simulated response curve
for high-performance filter
(pass band of 862-869 MHz)
achieving at least 50-dB rejection
at frequencies below 861 MHz,
given 1-MHz guard band.
RFS and Nextel find the
right combination
Nextel Communications is one of the USA’s
top five national wireless carriers, and
operates the largest integrated digital
enhanced
network
(iDEN)
system
in
the country. A unique working relationship
between Nextel and Radio Frequency
Systems has led to the cooperative development of assorted RF conditioning products—
including autotune combiners, developed
with the iDEN system in view.
Featuring
continuous
adjustment
of
monitoring
frequency
tuning,
and
the
safety channels. This is most likely where
deploy these high performance filters at all
autotune combiner allows multiple RF
iDEN and Cellular CDMA services are co-
commercial mobile radio transmission sites.
channels to be broadcast from a single
located; however, the overall situation
This will require a systematic overhaul of
antenna
will still be dramatically improved after
base station infrastructure, and should also
channel control. RFS offers two models
rebanding.
involve adherence to best installation
of autotune combiner: a six channel
other
practices. By ensuring that all accessories—
(ATC860-6) and a ‘dual four-channel’ unit
services can be more easily eliminated
such as connectors and jumpers—are
(ATC860R-DUAL-4). Similar in principle to
after rebanding using advanced filtering
correctly fitted and installed, the potential
the six-channel combiner, the dual four-
technology. The most noteworthy of these
for passive intermodulation products will
is the protection of the guard band
also be minimized.
Any
potential
interference
to
while
maintaining
very
tight
between 861 and 862 MHz. As part of the
15
rebanding process, commercial mobile
First time, on time
radio carriers must pledge to provide at
The decision to reband the 800-MHz
least 50-dB rejection at frequencies below
spectrum was undoubtedly not made
861 MHz.
lightly by the FCC. However, most industry
channel allows two independent sectors
The challenge here is the narrowness of
experts agree that the adopted plan will
to be controlled and provides two additional
the 1-MHz guard band, which requires
significantly
radio slots.
an RF filter exhibiting sharp attenuation
efficacy and timeliness of public safety and
At the heart of the relationship between
behaviour if the entire ESMR spectrum is to
emergency communications—where even
Nextel and RFS is a respect for the
be utilized (Figure 3). Such filters will be
ten minutes’ delay can have lasting
engineering expertise of both parties.
highly sophisticated, requiring multiple
ramifications.
interference
“Nextel realized that while they are the
resonant chambers (or poles) to achieve the
abatement strategies can help alleviate
expert in wireless networks and systems,
sharp attenuation behaviour. In addition,
the problem, but they are not all-
RFS is the expert in wireless components and
cross couplings, where dissipated RF energy
encompassing.
RF
is coupled back into the transmit path, will
The future US 800-MHz spectrum configu-
Cullinan, RFS Key Account Manager for
be required in order to compensate for the
ration will not only eliminate the bulk of the
Nextel. “It’s rather a unique relationship
increase in insertion loss that results from
interference threat to public safety radio,
for us—but a very effective one.”
increasing the number of poles.
but it will also facilitate filtering of out-
Where filters are to be used in iDEN
of-band emissions from commercial mobile
networks, the profile and distribution of the
radio
resonators will also need to be carefully
collisions caused by heterogeneity, the
designed
to
accommodate
the
improve
carriers.
the
Short-term
Instead
of
reliability,
products,”
says
Dick
high-traffic
high
stratified spectrum will streamline all forms
peak power ratings typical of the iDEN
of 800-MHz radio communications. The
transmitted signal—transmitted power is
road to this interference-free zone may
typically 75 to 100 W, with instantaneous
be arduous, as a three-year frequency
peaks of up 10 to 12 kW not uncommon.
relocation and retuning program for
In order to protect the non-cellular SMR,
hundreds of networks is set into motion,
public safety and B/ILT services operating
but it will be worth it in the long term.
below 861 MHz, it will be necessary to
conditioning
Autotune combiners have been
deployed at many commercial mobile
radio transmission sites to provide
filtering of out-of-band transmissions.
A rg e n t i n e m o b i l e
on the move
base
station
Movistar’s
antenna
CDMA
solutions
network,
and
for
RF
conditioning solutions for the Personal
network. CTI Movil’s network has also
benefited from RFS know-how in the
In the wake of Argentina’s economic lull, Radio Frequency Systems is
helping to haul the country’s wireless telecommunications sector onto
a new wave of technology, headed for 3G.
development of indoor coverage solutions
Some 30 kilometres north of San Juan, on
lifted all regional network restrictions. Thus
Local and loyal
the western border of Argentina, Carlos
begun the trials and subsequent launches
“Each Argentine network has special
Donoso just got a flat tyre. Carlos’s wife
of code division multiple access (CDMA)
requirements,” says Marcelo Angione, RFS
doesn’t know to delay her ‘carbonada
and time division multiple access (TDMA)
Commercial Director for Mercosur. “It’s very
criolla’ (veal and vegetable stew) by an
networks across the territory in both the
interesting working with the operators
hour, because outside of Argentina’s major
800- and 1900-MHz bands. In six years,
to develop new products, whether they
founded on RFS RADIAFLEX foam-dielectric
radiating cables, connectors and antennas.
cities and provinces, there is no mobile
coverage. In many cases, there is no fixed
coverage either.
However all this is changing.
For decades, a sunken local economy has
limited the growth in the Argentine
telecommunications sector; but a recent
economic
16
revival
has
made
it
the
REGIONAL FOCUS
playground of major Latin American and
global
A
telecommunication
once
network
cadaverous
is
slowly
providers.
fixed
telephone
being
expanded
and improved by incumbent operators.
Simultaneously, new service providers have
entered into the game with innovative
technologies for wireless communications.
The White Obelisk on Buenos Aires main
boulevard, the Avenida Nueve de Julio.
In early 2005, more than 20 per cent of
Argentines had been converted to the way
of wireless.
these networks have reached an advanced
be customized cable clamps or antennas
state, and the now-three main operators
for specific frequency allocations.”
The Argentine way of wireless
have been boldly rolling out global system
From its Latin American office, based in
Mobile telephony was introduced to
for
(GSM)
São Paulo, Brazil, RFS has built up close
Argentina in 1989, in the form of
networks in the 1900-MHz band. These are
relationships with all three major Argentine
Movicom/Bellsouth’s analogue advanced
known as Telefónica’s Movistar, Telecom de
network operators. The partnerships are
mobile phone system (AMPS) in the
Argentina’s Personal, and Telcel’s CTI Móvil.
founded on sound track-records and
800-MHz band. The next 10 years saw an
From the early days of the 90s, Radio
dedicated investment to training. RFS
almost incestuous struggle between four
Frequency
and
regularly organizes training sessions and
main foreign-owned and local operators,
customized solution sets have under-
workshops focussed on the deployment
where operations were limited by market
pinned the development of the Argentine
of cellular products, specifically for installers
access restrictions and exclusivity control
wireless networks. In particular, the main
or customers. “It’s like an unwritten
imposed by the government.
operators continue to rely on RFS’s popular
loyalty,” says Angione. “We’ve always
CELLFLEX foam-dielectric coaxial cable
done
granted personal communication system
as the backbone to their RF distribution.
operators’ needs; in return they’ve come to
(PCS) licenses in the 1900-MHz band and
Additionally RFS has developed specific
rely on us.”
In
1999,
the
Argentine
government
mobile
communications
Systems’
expertise
our
most
to
understand
the
RFS’s success in satisfying the operators’
Room to boom
are planned mainly for the GSM networks.
requirements has been largely due to its
According to Alexander Amador, RFS
“Argentina’s GSM network is 3G-ready,”
local manufacturing facility, established
Director of Marketing and Communica-
says Angione. There are many benefits of
over 30 years ago. Also based in São Paulo
tions Latin America, having a strong base
choosing a GSM path to 3G, he says. The
and recognized as one of RFS’s global
in
RFS
technology prevails in most countries
centres of excellence for base station
with
Argentina’s
and subsequently offers a cost-effective
antennas, the facility allows RFS to meet
telecommunications world of tomorrow.
solution in terms of products and product
the design demands specific to the Latin
“We’ve been in the region for a long
developments. Moreover, as the easy
American market.
time now, and we can see a trend that
choice for global roaming, migrating to
“Right now, Argentina’s mobile operators
started
GSM could make telecommunications the
are looking to optimize existing networks
continent,” says Amador.
and
Amador
minimize
the
visual
impact
of
Latin
America
market
in
has
insight
Brazil,
equates
imparted
into
travel
the
across
the
‘bridge in Argentina’s technological divide’.
developments
infrastructure,” says Angione. “Diplexers,
recently observed in Argentina to the
A mobile countryside
dual-band
specialized
beginnings of Brazil’s telecommunications
“However, before we think 3G, we must
RF conditioning products are most in
‘explosion’ that occurred in 2003 and
make wireless more accessible to more of
antennas
and
the population.” Angione says this means
extending coverage outside the major
provinces—to where Carlos Donoso is still
stranded—and into the rural areas. It also
means reducing the CAPEX and OPEX of
new and existing services that supply a population, 25 per cent of which is below the
poverty line.
17
In order to do this, Argentina’s mobile
operators
are
exploring
innovative
technologies, such as CDMA in the
450-MHz band. “The lower the frequency,
the longer the wavelength, the fewer
base-stations required, and therefore the
higher the cost-efficiency,” says Angione.
Other than the low cost of deployment,
which equates to a 60 per cent saving on a
demand.” RFS has developed new RF
2004. “We see the boom starting in
CDMA 1900 network, CDMA 450 provides
filtering technologies to assist in base-
Argentina in 2005, and we know what
an easy upgrade path to 3G technologies.
station co-location, plus design modifica-
to expect.” What’s more, with a mobile
The CDMA 450 concept was originally and
tions to cope with the climactic challenges
penetration of less than 30 per cent,
successfully conceived as an upgrade of
presented by a country such as Argentina.
Argentina’s wireless sector has plenty
Russian analogue services in the 450-MHz
With some diurnal temperature swings
of room to boom.
frequency band. Argentina began the
between 50 and 32 degrees Celsius, and
Angione also predicts growth—especially
deployment of its brand new CDMA
above
for the GSM networks—in all the key cities:
450 network in January 2005. “RFS also
the 90 per cent mark, the Argentine
Mendoza, Santa Fe, San Juan and Resistencia,
has a strong presence in Russia,” says
territory is a test for wireless equipment
and 10 to 20 per cent more so in Buenos
Angione. “So again, through our global
manufacturers. “For the Buenos Aires
Aires. At end-2004, Movistar reported
experience, we are familiar with the
area, for example, all our diplexers and
more than 5.7 million subscribers, a market
technological wireless needs of Argentina
connectors have IP68 enclosure-ratings
share of 42 per cent, ahead of Personal
today and also tomorrow.”
and extra robust designs to deal with
and CTI Móvil. While all three operators
the elevated moisture levels in the air,”
plan to maintain their TDMA and CDMA
says Angione.
networks, development and expansion
relative
humidity
levels
often
Pa r t i c l e a c c e l e ra t o r g e t s
R F S ‘ i n - t u n n e l ’ t re a t m e n t
18
The world’s largest particle physics laboratory
light. To produce the very high magnetic fields
—the giant Large Hadron Collider (LHC)—
required to control the protons’ trajectory, the
reached a significant milestone in March
LHC will incorporate some 1232 supercon-
2005, with the positioning of the LHC’s first
ducting dipole magnets—each weighing
superconducting dipole magnet. Currently
35 tonnes and measuring 15 metres in length.
being constructed deep underground in
Located along the length of the particle
the Swiss/French border region, the most
beam’s massive circular route, the magnets
distinctive feature of the LHC is the 27-km
feature superconducting magnet coils that
circumference tunnel that houses the proton
are cooled to -271 degrees Celsius, thus
accelerator ring—a tunnel furnished with
permitting extremely high current without
cellular communications supported by Radio
loss of energy.
Frequency Systems.
To provide the vital in-tunnel communications
Operated by the European Organization for
needed for the LHC’s construction and
Nuclear Research (CERN), the new LHC is
maintenance crews, CERN has incorporated a
planned to be completed by 2007. Located
self-contained cellular communications system
some 50 to 100 metres below the earth’s
throughout the LHC ring-tunnel. In support of
surface, the LHC will ultimately accelerate
this, RFS has provided a total of 125 kilometres
particles to speeds approaching the speed of
of RFS CELLFLEX foam-dielectric trans-
Photo: CERN
IN TOUCH
R F S m a ke s i m p a c t w i t h
l o w - i m p a c t i n S i n g a p o re
Visit RFS at
When Singapore hosts the Asia Pacific
In response to this demand, RFS will display
CommunicAsia/BroadcastAsia 2005:
region’s
examples from its range of low visual
June 14 to 17, 2005
two
leading
communications
technology exhibitions this June, Radio
impact
Frequency
Systems
antenna
solutions.
In
Singapore Expo
demonstrate
addition to providing azimuth adjustment
elements of its extensive portfolio of
of individual antennas, the low-profile
cutting-edge total RF system solutions.
cluster assemblies can also incorporate
integrity and current connector inventories.
RFS’s focus at CommunicAsia 2005 will be
integrated
amplifiers
RFS will also demonstrate its extensive
the provision of third-generation (3G)
(TMA) and treated surface camouflage
global experience in the deployment of
cellular systems, where low visual impact
options.
digital RF broadcast systems. New products
solutions are proving vital across the region.
Other important new 3G-ready products on
will include the company’s CPF-series
“The emergence of 3G is demanding the
display at CommunicAsia 2005 will include
side-mounted FM antenna, which offers a
deployment of new base stations, which is
the company’s enhanced CELLFLEX ‘A’
low-cost, lightweight solution for low to
challenging when all the best sites are
premium attenuation transmission line.
medium power applications in the 87.5 to
already in use,” said Peter Walters, RFS
Offering a further reduction in feeder
108 MHz band; and a range of compact
Marketing
Pacific.
attenuation up to five per cent at 2100 MHz,
200-millimetre folded UHF filters that can
“Negotiation for new sites is a sensitive
this new variant has been specifically devel-
provide critical digital transmitter masking.
issue. Site owners are generally more
oped to meet the demanding requirements
In addition, RFS will introduce its ‘RD’
amenable if antenna systems appear
of 3G cellular networks, while retaining
wideband slot cavity antenna to Asia
environmentally friendly.”
ease of cable handling, mechanical
Pacific audiences.
Manager
will
cluster
for
Asia
tower-mounted
Hall 4, Booth E2-07
mission line and RADIAFLEX radiating cable.
According to RFS Regional Sales Manager,
Harald
Zietz,
demanded
an
this
unique
equally
application
unique
PREVIEW
STAY CONNECTED
4th quarter 2005
cabling
solution. “We worked with CERN to ensure
Strumming the HAARP
that the cable was suitably radiation resistant,
Deep in the wilds of Alaska stands one of
as quite high radiation levels are achieved in
the largest planar antenna arrays on
the tunnel during the experiments,” he said.
the planet—the High-frequency Active
“To this end, the cable jackets were tailor-
Auroral
made to CERN’s specific requirements.”
Spanning 36 acres (14 hectares) in area,
To mark the occasion of the positioning of the
the 180-tower array is used to conduct
first superconducting dipole magnet, RFS
scientific research into the properties
along with 28 other CERN-supporting com-
and behaviour of the upper atmosphere,
panies, participated in a technology exhibition
with the view to improving global wireless
at CERN’s Geneva headquarters. Held during
communications.
Research
Program
(HAARP).
the first week of March, the exhibition—
One of the Large Hadron Collider’s 1232
super conducting dipole magnets under
construction.
‘Germany at CERN’—was organized by
Since the first towers were erected in 1993,
Germany’s Federal Ministry of Education and
Radio Frequency Systems has been the
Research (BMBF). As part of this event, RFS’s
primary supplier of coaxial transmission line
Global Product Manager for Wireless Distrib-
for the HAARP array. Working closely with
uted Communications Systems, Dr Peter
the array’s designer, builder and operator,
Raabe, presented a paper to CERN executives
BAE
entitled ‘Wireless distributed communication
RFS has developed a customized feeder
systems in tunnels and confined areas’.
connector solution to defeat the impact
Systems
Advanced
Technologies,
IN TOUCH
Brunei TV goes
digital
of Alaska’s inhospitable climate. The latest
phase of the installation involves the
installation of around 1800 connectors
in total—along with over 40,000 feet
(12 kilometres) of transmission line.
Radio Television Brunei has promised
The RFS UD series dipole array is a
its
viewing
vertically polarized antenna that supports
In the next issue of STAY CONNECTED, we’ll
experience by 2006, with the proposed
the entire UHF band in two models:
take you on a guided tour of Alaska’s
introduction of digital television (DTV).
470 to 650 MHz and 620 to 860 MHz
HAARP antenna and transmitter system,
Trials for the new single service broad-
frequency bands. Available in four-,
plus expand on the unique engineering
casting
for
eight- and 12-bay configurations, the UD
relationship
mid-2005, with Radio Frequency Systems
series offers nominal mid-band gains of
Systems
providing the essential broadband UHF
nine to 14 dBd. Constructed in aluminium
HAARP possible.
dipole array—a four-bay ‘UD’ series
and housed within a fiberglass radome,
dipole array.
the antenna is cyclone-rated, and thus
“For the purpose of the trial the RFS 4UD
able to resist wind speeds of up to 230
is the ideal antenna,” said Mick Bennett,
kilometres per hour.
RFS Broadcast Systems Engineer. “At
“We’ve had a lot of experience with such
100 to 200 W, it’s low power and,
DTV trial projects around the world,” said
importantly, it’s got low wind loading.”
Bennett. “So we really understand the
In terms of installation, the low wind
system, without needing to complicate
loading of the RFS 4UD dipole array
or over-engineer the solution.”
audience
an
standard
enhanced
are
planned
facilitates installation of the array and
integration into the entire DTV system.
between
that
makes
RFS
and
strumming
BAE
the
19
RADIO FREQUENCY SYSTEMS
The Clear Choice™
Please visit us at www.rfsworld.com