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physical and mvirnnmmtal rrquiremcntr ktr npcratitsn
ahrud a .p.crcrdt. url design uul fahricarc nn mclnsurr
suitable lor rpare flight
1.2 Fm)load lechnoloplrr
In additton tn providing more rmm lirr payloads nn
satcllitcs. cc intcnd w increase the nunihrr ul hits or
pixels per pnund for communicatinn. and optical
paylods. Se .rial p ~ects have ken inilintcd lo clo just
hi. In IM mtim. we discurs snmc 01 ow EIIF. UHF md
kaur mmmuni'atbn initiatives and several i4 our olitical
tcchnoli~y~cs Inilialiver.
2 2 I Ellf
2.2 1.1 Psrylmd ctmctp
The mnst promiwnK. new. near-trrm ieclindngy lor
protected cnmmuniralions employs :he EllF hand
(apprnxm.tcly &I Ctlt uplinks MJ approaimmly 20 Gllr
duwnlink.). The ASTP hu several tcchnolv&y yrojku
underway that syncrgisticallv complrmenl and support
other Do0 work in the ENT arena. including the
applictlim of advanced technnlngies that ruuld
significantly rrduce the site. weight. volume MJ p~rwcr
requtrrmmu 01 exisling EllF sysicms. We ue striving lor
a hS percent rrhction in quL4 pnwer compunl with the
present tcchnntopy hase. Within five years. further
lechnology mdrances should provide an dditiunal
30 prrccnt reduction in weight MJ pnwcr. hescntly. our
audoes indt;alc a payload weigh1 01 ipprnximalely
67 purds br a 15.rhanncl. low data raw (LDR) EllF
package IS pssihle (compul tn the eai%ting 225.pnund
package). A highly efficicnl. 2 walls. 20 Cllr
IrUIsrI.illmg. high.powcr amplifier yields on overall
eI!iciency ol at leas1 35 percent; it USCI a rsctntly
deweloped (DARP Spnnsored) CaAs permeahlo hase
umsism?. AI&# developed for thit pnject ire a
high-spcrd signal proensor. lightweight signs1 generator
ud lighlweight scanning anlenna. The U Ollr vulning
amna hms a variahle brunwidh. making it capable of
operating in elliptic. U well U circulu. orbits.
2.2.1.2 Sphrriral Lew AIVewsa
The Sphcricml Lens Antma prsjcct has as its ohjcclive
the development of a wide licld-of-view (WFOV).
elcctmnic scmning. multibum EHF mmna cspahlc of
nulling interfering sqnds md operating in a vuiciy of
orbiu. inludin8 those that arc highly elliptical. The
munna's radiatinp apenure is 8 splm of Mlid dielectric
Ih.1 provides a graduated index ol refraction la furm the
ractating .p*tum. Fsedhorru 10 VrMgcd with equal
~p~:hg on a concwo spherical awfica adjacent to he
dielectric sphere. TO lorn .n electronically scmcd
UIVNI% any one of a luge number of fee& b ercited
hhmugh UI interleaved. switched lrm network, which CM
combine c l u r of ~ horns 10 perform complex nulling or
CUI 5c wed for simple swivhcd beam operations. The size
or the lens dcpcnds on lk minimum gain requirement
(0.8.. for 2.5 38 minium gain, cha lens would measure
apparimately 2.5 inches in dimeter at a fryucncy of
44.5 GHt). The estimated sirs or lk uuenna (lens.
horns md switch U-) h 12-inch dimeter cylinder and
rJ inches long.
2.2.2 UllF
The mosi widely used d. unfomnutely. most vulnerable
mililuy satellite communication (MJLPATCOM) frequency
band is UHF. The Multiple Path, Beyond Line-of-Sight
(MUBL) Communication effort is aimed at providing
interference-resistant voice communications among
affordable. handheld UHF terminds having appmaimatcly
5 warn of RF OUQul. The concept provides a singlc.hop
capability (U seen by the user terminal): it may be lhought
or U M amplifying ionosphere. No salel~ile crntrlinlring
is contcmplated. When more t h one ~ satellite is in view
of the communicating terminal pair. there are multiple
popagation pah. "be modulation nnd coding system is
designed W sdppon this and resist interference from other
satellites. In addition UI satellites. MUBL CUI ba mounted
on high altitude balloons. mountaintops or unmanned
aerial vehiclh. Successful implementation of these
concepu could rubsumtially alleviate shortcomings noted
in che went Dcmt Storm operations.
2.2.3 SatrlliteiSubmarine Laser Communications
Initiatives
A number of laser communicarions studies and
demonslrrlions are underway or have been completed by
rhe ASTP. n\ec common objective is U) dcvelop reliable.
two-way luer communications systems. For submarines
having OlpMded operational depth and speed envelops.
laser communications povidcs the plential for timely
message delivery at wdul umsmission rates. Current
submuim communications can be enhanced through the
use of bluegem laser technology. Submarine laser
communications sysmnu will require small. lishtwcight.
pime power cllicient laser5 Md nmow spccaal blnd wide
t3ld.c.f-view optical fillen. The ASTP h u scverd blue-
]Ireen laser Pmjccts that address these challenges. AI
pesent. here development efforu focus on he Cesium
Atomic Relonmce Filter (Cs 4RR md alternste narrow
handpass filters. as well as several laser umsmitter
technologies. All cr there technologies ue being
developed for rapid insertion ino ..aididate spaceborne
luer communisations systcmr.
223.1 CeJiwm Alm'c ReJoMnre Filter
The Cs ARP pm~~ct U desigmd w investigate enabling
technologies IO support srlellile-to-submarine laser
communications. Specific ueu of investigation are
satellite system concrpt delinition and uplink rrceiver
kcadboud design ckvelopncnl ud testin& The Cs ARF
raciver a p u h utilims a unique side-znupled Cs ARF U
h buis fur he 4.rell anay ('igmc 3). This approach
porrJcs very gomi hoadbmd signal rcjcctinn wtlh
erc..plionally high mband sipnal throughout. Our
Iimdings w-date have resulted in an order of magnitude
improvement in cell efficiency fra 4 percent to over
47 percent.