sat com tech oct 2011

8/2/2019 Sat Com Tech Oct 2011

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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


2/8

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


3/8

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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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 (


6/8


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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

sat com tech oct 2011

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