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8/2/2019 Sat Com Tech Oct 2011
1/8
s
October 2011 For the Engineer, by the EngineerSatcomT E C H N O L O G Y
www.viasatellite.com
Accessing
Content OntheMove
Presents New Opportunities
for Satellite
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2 Satcom Technology October 2011
Vice President and Group Publisher Via Satellite
Joe Rosone
Divisional President, Business Information Group
Heather Farley
Associate Editor Via Satellite
Mark Holmes
Director, Satellite Online
Julie Blondeau Samuel
Managing Editor Via Satellite
Debra Richards
News Editor Satellite Today
Jeff Hill
Senior Graphic Designer Via Satellite
Vince Lim
Production Manager Via Satellite
Sophie ChanWood
Chief Executive Officer Access Intelligence, LLC.
Don Pazour
Accessing Content
on-the-Move Presents New
Opportunities for Satellite
W
hether users are on arplanes, cruse shps or trans,
one thng s untng them the demand for data com-
muncaton and vdeo servces on ther moble or tabletdevces. Wth most users utlzng data and vdeo servces as
much as voce servces on ther moble devces, ths s presentng a new range of opportun-
tes for satellte technology vendors as they look to supply the technology that wll enable
users to have connectvty pretty much wherever they are.
Amplier technology companes must rase ther game to meet the next set of demands, as
users are expectng qualty connectvty servces on-the-move. It s a challenge they are enthusas-
tcally embracng, as many see ths as a potentally lucratve opportunty for satellte companes,
both on the operator sde and the technology sde.
Certanly, Ka-band satelltes wll have a huge mpact on enablng the next generaton of commu-
ncatons on-the-move servces. One company that ams to be at the forefront of provdng the nec-
essary technology to power these servces s Wavestream. The company has hgh hopes for ts
Grd Amplier, whch t sees as becomng an ntegral pece of the equaton for satellte operators
nvestng aggressvely nto Ka-band satelltes. Wth a number of Ka-band satelltes gettng ready to
launch, Wavestream s conident that ts amplier technology wll play a key role.
However, state-of-the-art connectvty s about more than just Ka-band, although t s a key part
of the debate. ITS Electroncs, a company based n Greater Toronto, Canada, whch also plays
n the Ka-band space, s also lookng to offer a wder range of solutons. Its range of Sold State
Power Ampliers (SSPAs) am to provde compellng and eficent solutons to satellte operators
delverng on-the-move servces.
The latest edton of Satcom Technology contnues our pledge to brng you nformaton for the
engneer, by the engneer, and we are sure you wll ind t
nformatve and a great resource when consderng your next
moves n mprovng your communcatons nfrastructure.
M E S S A G E F R O M T H E E D I T O R
4 Choke Cherry Road, 2nd FloorRockville, MD 20850Phone: 301/354-2000, Fax: 301/340-3169Email: [email protected]: www.viasatellite.com
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October 2011 Satcom Technoogy 3
Demand for high-speed, reliable connectivity to the Internet is being driven by a worldwide expectation that plat-
forms and applications will provide that access anytime, anywhere. Ka-band satellite services are coming online at
just the right time to address this exponential growth.
The Ka-band Revolution
Gary Echo, VP Busness Deveopment at Wavestream, [email protected]
B
ack n 1968, the Beates
asked us f we wanted a
Revouton. Ive spent neary30 years n satcom and have wt-
nessed many technoogca chang-
es n that tme. Some of these
changes have arguaby been revo-
utonary, but most of these have
been transparent to peope outsde
our ndustry. I beeve that s about
to change n a dramatc, revouton-
ary way. The advent of hgh-band-
wdth, Ka-band satete servces s
gong to brng satcom drecty nto
the hands of a arge percentage of
the word popuaton.
Why now? you mght ask. Ka-
band has been around for more
than a decade. What about the
attempts by Teedesc, Astronk,
Ceestr, Skybrdge and others?
What s so dfferent now?
What s dfferent now s that
we are at a convergence of
technooges both from the
demand sde and from the
suppy sde. Demand for bts
s ncreasng exponentay, not
ony n the amount of bts beng
consumed, but aso n the number
of ndvduas consumng them
and reachng nto ther waets
to pay for them. Meanwhe,
satcom technoogsts from many
satcom ieds (modem, encoder,
antenna, satete) have mproved
ther wdgets to the pont where
deverng bts can be done at aprce that both the user s wng
to pay and at a prce a servce
provder s wng to dever or,
n an subsdzed stuaton, togenerate ncrementa revenue.
Indeed, smartphones, Pads and
other Internet-enabed devces are
becomng ubqutous. Consumers
are demandng contnua access
to the Internet and streamng
servces, and are wng to
pay a szeabe porton of ther
dscretonary ncome to secure that
access. The average ce phone b
has been rsng steady and today,
many spend more on ther data
pan than they do on voce. The ce
phone s now more about stayng
connected va ema, Facebook
and Twtter, and much ess about
makng phone cas. Ths s very
true for busness users. It s hard
to ind, even n the nerd herd,
someone wth an antquated ce
phone wth no keyboard. I take
notce of these thngs. There are
st some hodouts (weve had
them at Wavestream) but some
of these foks secrety keep a
Backberry n ther brefcase, I just
know t. A these users want to
reman connected wth hgh-speed,
reabe servce whether they are
n ther homes, cars, on a tran, on
a cruse or on a pane. Asde from
the fact there s a stranger sttng
next to us n 23E, on the arpane
we want the same streamng
Netlx experence to our Pad aswe have whe sttng n our vng
room. Arnes are gearng up to
dever that experence and more.
The demand for bts snt justcomng from consumers and bus-
ness peope. The mtary, home-
and securty, NGOs (FEMA, Red
Cross) are a adoptng technoogy
to better perform ther dutes and
keep us safe. These technooges
requre ever ncreasng bandwdth
and tmey devery. Specicay,
magery s a sgnicant bandwdth
hog. Around the word, demand for
connectvty s ceary vsbe n the
vast use of soca meda to com-
muncate. Aggregated, thousands
of users dong text, ema and
soca networkng, s a ot of bts
to get to/from the Internet from a
manner of ocaes.
Ka-band
Ready for Prime Time
The chaenge to the satcom ndus-
try s how to dever hgh-bandwdth
to users wherever they may be. For
many patforms, the satcom ndustry
aone owns ths chaenge. We are
not gong to see fber to Fght 99.
Terrestra can provde some servce
to arcraft over and, but speeds are
mted. Recenty, a terrestra-based
servce to arcraft had to bock a
users from upoadng mages to
ther Facebook pages. That s not
gong to fy, teray. If you just fn-
shed your vacaton and rushed to
the pane, you are gong to want toupoad those mages. Users w
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4 Satcom Technology October 2011
demand, and wll get, full connectv-ty by talkng wth ther wallets ether
by payng for hgh-speed access
drectly or by payng extra to fly on
arlnes that support ther lfestyles.
Ku-band can delver mproved ser-
vce to n-moton platforms and n
fact s dong so today to a lmted,
but growng extent. Bandwdth,
however, has become the lmtng
factor. Ku-band satellte slots are
practcally fully populated and the
satelltes n these slots are hghlyutlzed today. 750 MHz of capacty
n each polarzaton wth regonal or
hem beams s not a lot of capacty
when you consder the aggregated
demand from moble users.
Ka-band s the key to delverng
to ths consumer mandate. Frst,
Ka-band has 3.5 GHz of avalable
bandwdth per polarzaton vce
0.75 GHz for Ku. Ka-band further
augments ts basc bandwdth ad-
vantage wth the use of spot beams
and frequency re-use (colors as they
are called). Ka-Sat s advertsed
at 70 Gbps throughput; VaSat-1,
at 130 Gbps. That s almost 100
tmes the capacty of a Ku-band
brd. The space sde of the ndustry
s posed to delver a vast amount
of Ka-band bandwdth. One satellte
s around 100 Gbps.
Now multply ths per-
satellte throughput by
the number of roughly
150 open orbtal slots
(and that just counts
the GEOs), and you see
a true revoluton n the
access to bts and the
cost per bt.
Revolutionary
Technology
Wavestream is Born
Rewnd to the 1990sand the efforts of Teledesc and
other large constellaton Ka-bandefforts. That s the geness of
Wavestream. A couple of PhDs from
Caltech set out to commercalze a
technology they had been workng
on n the Caltech labs called quas-
optcal combnng. They took some
angel nvestment and boldly set
out to go where no one had gone
before: take a free-space
confguraton and condense t
nto WR-28 wavegude. Some
mght call ths effort noble.Fgure 1 shows an early test
setup usng a one-foot lens to
llumnate one of ther devces
n the Caltech lab.
The resultng technology s
called the Grd amplier. The
name comes from the struc-
ture of the amplier tself: a
grd of unt cells. Each unt cell
has a par of antennas wth a
par of transstors between.
One set of antennas grabs ts
pece of the ncomng sgnal,
and the amplied sgnal s
put out nto the wavegude by
the output antennas. A grd
of unt cells s mounted co-planar
on a ceramc carrer, whch s then
mounted to a heat spreader. The unt
cells are spaced closely together
such that they effectvely operaten concert on an entre wave. The
result s an amplicaton devce that
takes a plane wave mpngng on
ts backsde and puts an amplied
verson out ts front. Ths devce s
placed nsde a WR-28 wavegude as
shown n Fgure 2. The igure actually
shows a two-stage amplier module.
The Grd amp rotates the sgnal 90
degrees due to the orthogonal rela-
tonshp between nput and output
antennas. By usng two stages, the
wavegude stays n the module n
the same orentaton as the output.
Havng two stages allows for basng
the irst stage for gan and second
for output power. The Grd amplier
s a unque, and obvously patented,
archtecture that provdes hgh-power
at hgh frequences. Whle ths artcle
s focused manly on Ka-band, the
Grd amplier s also well suted to
frequences up to 100 GHz.
Fgure 3 compares the Grd to
10 ndvdual devces currentlyon the market. The red dot sFigure1: Illuminating Early Grid Amps
Figure2: Illuminating Early Grid Amps
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October 2011 Satcom Technoogy 5
Wavestreams devce at 22W outputpower wth 17 percent Power Added
Eficency (PAE).
A Grd modue wth WR-28 output
provdes 15W saturated power wth
8W of near power n a 4-ounce
package. When addressng cha-
engng mobe coniguratons, t s
crtca to mount the ampier as
cose to the antenna as possbe.
Ths mnmzes osses, whch, at
Ka-band, are sgnicant even over
wavegude (0.75 dB per meter). Theghter the ampier, the easer fe s
for the antenna postonng system.
As the market moves to lat pane
arrays, the sze of the ampier starts
to become more mportant, and the
Grd ampiers compact power has
added beneits.
An advantage of the Grd archtec-
ture s the devce mountng to the
heat spreader wth rada transfer of
heat to a surfaces. Ths mountng
coniguraton provdes fary eficent
therma transfer, whch mantans
ower juncton temperatures and
yeds hgher Mean Tme Between
Faures (MTBF). Comparatvey,
wth tradtona MMIC devces the
majorty of the heat s n the astbnary stage as depcted n Fgure 5
(eft). The ampier desgners usng
these devces are forced to get heat
out of that tny strp. In these MMIC
devces, gettng that heat out can
be a rea chaenge partcuary for
GaN devces that have hgher power
denstes as compared to GaAs.
Another advantage of the Grd s
that the sgna never transts a bond
wre. The ony bond wres on a Grd
amp are used for DC, and there are
redundant bond wres
from each edge. For
the ampier to ose
any power t woud
take two bond wres
to fa and they woud
have to be both on the
same coumn. Even n
ths unkey scenaro,
the ampier woud
ose ony 1/11th of ts
power. I know, remarkabe.
Demand to In-Hand
Up to now we have taked about
the scence of the ampfer, but
t s mportant to understand the
appcaton of the scence. Scence
by nature s hard and not every
good dea yeds usabe resuts.
For the nventor/desgner (and
obvousy to the nvestor) t s aways
rewardng when a good dea and
a the effort pays off. In the caseof the Grd amp, we beeve we
have succeeded. Snce the frstdevery n 2008, Wavestream has
shpped more than 4,000 Ka-band
ampfers. If we excude ampfers
for consumer broadband (
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8 Satcom Technology October 2011
power supply wth, other nstruments
on one platform. As a result, the HPAs requred to have low conducted
and radated
emssons for
electromagnetc
compatblty
(EMC) wth other
equpment. The
demand on
system EMC af-
fects the choce
of TWTA or SSPA. A TWTA requres very
hgh voltage DC sources, rangng from10 kV to 18 kV, to bas the cathode
and the helx col. It requres a power
converter that steps up the AC lne
voltage to the klovolt range, and rect-
ies t wth hgh breakdown swtchng
crcuts. In contrast, SSPAs utlze GaAs
or GaN transstor technologes that op-
erate at low voltages, e.g. 6 V for Ka-
band 0.15 m pHEMT transstors, 10
V for X-band GaAs FETs and up to 50
V DC for GaN. It s a challenge to sup-
press the hgh voltage rpples present
n the TWTA power converters. Further-
more, the choce of large capactors
and ilters that can wthstand tens of
klovolts breakdown s lmted. On the
other hand, EMI ilters n SSPAs can be
desgned usng a wde varety of com-
ponents, such as electrolytc, tantalum
and ceramc capactors, together wth
common-mode chokes to suppress
the rpples. As a result, the TWTAs
generally have nferor EMC compared
to SSPAs. Fnally, the hgh voltages n
TWTAs cause more stresses to the cr-
cut components. Therefore, the power
supples used n SSPAs generally enjoy
hgher MTBFs than those n TWTAs.
Many ITSs SSPAs are desgned to
comply wth EMC standards such as
EN55022 and MIL-STD-461E for ml-
tary applcatons. These SSPAs utlzes
EMC certied AC-to-DC step-down
converters or DC-to-DC step-down con-
verters to provde the bas voltages tothe transstors. Lnear regulators are
utlzed to enhance the lne regulaton
(mmunty to the power supply rpple)and the load regulaton of crtcal bas
crcuts for the power transstors.
To acheve hgh avalablty for a
satellte communcaton lnk, SSPAs,
whch have graceful degradaton
characterstcs, are the preferred
choce over TWTAs. When a TWTA fals,
the tube s usually damaged beyond
meanngful usage. Buldng a 2-to-1
redundant HPA wth TWTA also doubles
the cost and sze because two TWTAs
are requred nstead of one. Therefore,redundancy may not be feasble n
hghly moble (.e. portable) SATCOM
termnals. The redundancy mplemen-
taton also mposes addtonal loss
to the output power of the TWTA. The
repar s also costly, because the entre
travellng wave tube must be replaced.
The above problems can be mtgated
by usng SSPAs nstead of TWTAs.
Although the output power of a tran-
sstor s clearly nferor to one mghty
TWTA, numerous sold-state amplier
modules can be combned together
to acheve graceful degradaton. For a
SSPA comprsng N amplier modules,
the power drop due to one faled mod-
ule s 20*log10((N-1)/N). For example,
f a hgh-power SSPA comprses eght
amplier modules and one module
fals, the output power wll only drop
by 1.2 dB. The falure of the SSPA s
graceful not only n the mnor output
power degradaton, but the reman-
ng seven modules contnuously and
fathfully transmt every sngle RF cycle
of the symbols before, durng and after
the module falure. Snce no IF symbol
are mssed durng symbol recovery
by the recever, the satellte lnk s
not dsrupted by the mssng data. As
mentoned prevously, the mnor power
drop does not readly degrade the BER
of QPSK or 8PSK demodulaton. ITS
Electroncs SSPAs have the beneit
of graceful degradaton because theyutlze multple transstors for power
amplicaton. The companys patented
nnovatve solutons n hgh-frequencyhgh-power combnng technques
make ts products attractvely scalable,
thanks to hgh-eficency, and small
sze and weght.
ITS hgh-power SSPA technology ut-
lzes amplier modules that are com-
pact and often hot-swappable. A power
module, whch s attractvely prced at
a fracton of the overall SSPA, provdes
an economc opton for n-stu repar.
For example, a warshp patrollng on
open sea can be equpped wth extralow-cost amplier modules. In the un-
lkely event of a SSPA module falure,
t s unacceptable that the satellte
lnk s down untl
the shp must be re-
turned to port for the
repar. Instead, the
repar can be per-
formed rght on the
sea. The on-shp
crews can replace
the SSPA module
wthn 15 mnutes,
whle the satellte lnk s unnterrupted
durng the entre msson. The redun-
dancy advantages can be extended
by usng hot-swappable power supply
modules and fan modules for cost-
effectve mantenance.
ITS Electroncs products serve the
government, defense and commer-
cal communcaton markets n the
L, X, Ku/K/Ka and Q/V frequency
bands. ITS equpment has been
desgned and certied complant to
MIL-STD-188-164A
to operate wth the
Wdeband Global
SATCOM (WGS)
satelltes. The
companys equp-
ment powers gate-
ways for Ka-Sat,
Spaceway, IPSTAR,
WINDS, Vasat-1among others.
Figure 2: ITS 90W 29.1-29.3GHz SSPA replacement ofTWTA in IRIDIUM Gateways,year 1999
Figure 3: ITS 40- to60-Watt Ka-bandSatcom Block UpConverter
Figure 4: ITS airborneKu-band 20-Watt HPA,
High IP3 LNA and LowLoss Diplexer