advanced antenna technology for a broadband ka-band … · 2017-12-16 · 2010. trw’s gen*star...

Advanced Antenna Technology for a Broadband Ka-Band Communication Satellite

Technology Review Journal • Spring/Summer 2002 37

Advanced Antenna Technology for a BroadbandKa-Band Communication Satellite

Charles W. Chandler, Leonard A. Hoey, Ann L. Peebles, andMakkalon EmTRW Space & Electronics, Engineering

The needs of the Ka-band broadband market have been assessed by numerousantenna trade studies. Wide-coverage, wide-bandwidth, low-noise communica-tion systems with high effective isotropic radiated power (EIRP) must haveconfigurable spot beams to meet the flexible distribution demands of bandwidthand power into high-traffic areas. The trend is toward larger effective apertures,a significantly higher number of smaller beams, higher EIRP, a higher gain-to-temperature ratio, more complex switching/combining functions, and onboardprocessing functions. Satisfying those demands will require an antenna technol-ogy significantly more advanced than that employed by current wide-area-coverage transponder systems. TRW has developed a new generation of broad-band communication satellite antennas for Gen*Star, a TRW-built advancedspace-based broadband digital communication system for the emerging Ka-band market. The Gen*Star family of precision high-gain satellite antennasaddresses the future needs of the Ka-band market. Performance results exceedthose previously shown for other systems. Since future markets may develop inunforeseen ways, the Gen*Star family of antennas has design features flexibleenough to meet future market demands.

Introduction

In response to the demand for broadband satellite systems and services, TRW hasdeveloped Gen*Star, an advanced space-based broadband digital communication systemfor the emerging Ka-band market. With dynamic communication links and sophisticatedonboard signal and data processing, Gen*Star provides broadband connectivity withseamless interfaces to a terrestrial infrastructure, using technologies designed to operate inspace for years. In addition, key design features make the system flexible and robustenough to meet future market needs. The development and capabilities of Gen*Star’sprocessing payload were detailed in a previous Technology Review Journal article [1].Here, however, we describe the key design trades of Gen*Star’s multiple-beam antenna(MBA) system.

To meet a steadily increasing demand for satellite capacity, MBAs have become commonin satellite communication systems. MBA systems enable frequency reuse by maximizingcapacity, while minimizing required frequency allocation. Service providers can use spotbeams to concentrate coverage in high-demand areas, rather than supplying wide-areacoverage that may include areas with little or no demand. Gen*Star, for example, providesa full-Earth field of view (FOV) from a single satellite in geosynchronous Earth orbit(Figure 1).

http://www.ms.northropgrumman.com/PDFs/TRJ/TRJ-2002/SS/02SS_TOC.pdf


Technology Review Journal • Spring/Summer 200238

Another benefit of higher-frequency MBA systems is their ability to operate with broaderbandwidths in the Ka- and V-band frequency regions; the spacecraft is thus able toaccommodate smaller antennas. Many new MBA systems now under construction willoperate in the Ka-band. Future systems being planned for the V-band, which permitssignificantly smaller antennas than even the Ka-band, should be operational by about2010. TRW’s Gen*Star antennas are some of the first to be designed for the Ka-band.Table 1 details 11 major Ka- and V-band satellite systems planned by various serviceproviders for operation in the near future.

Key MBA System Performance Parameters

MBA system design involves trades in several key performance parameters:• Antenna gain. Affects DC power, capacity, and ground terminal size. High-gain

antennas minimize power consumption and terminal size, while maximizing capacity.• Number of beams. Determines the percentage of the desired coverage area available.

In addition, their dwell times drive the demand for bandwidth. The available space-craft power also determines the number of simultaneous beams.

• Carrier-to-interference (C/I) ratio. Measures the signal-to-“noise” performance,where the equivalent noise is interference from adjacent beams. A high C/I ratioenables maximal frequency reuse, thereby maximizing capacity. Figure 2 showsthe representative sources and levels of interference in a two-dimensional cut of ahypothetical typical beam set. Typical requirements include a four- or sevenfoldreuse spacing in densely populated areas. MBA systems must meet stringent cross-polarization and side-lobe-level requirements, because of a high degree of frequencyreuse and tight beam spacing. For many MBA systems, however, performance islimited by composite interference from surrounding beams, rather than noise. In thosecases, the coverage area must be limited to that in which low cross-polarization andside-lobe levels are achieved, resulting in decreased capacity or penalties on the

Figure 1. Gen*Star’s full-Earth FOV enabled by its MBA system optics



terminal design. MBA gain and C/I performance typically degrade as the angle offboresight (scan angle) increases, limiting most MBA systems to regional or nationalcoverage areas—and thus also limiting the system global capacity.

• Coverage flexibility. Defines the ability of the antenna to provide high-performancecoverage across a wide FOV. Antennas with excellent coverage capability give thesatellite service provider greater flexibility in deployment, sparing, and recoveryplanning. The optimal selection will also minimize the number of satellites.

• Spacecraft accommodation. Specifies the compatibility of the antenna system withthe spacecraft bus. An antenna with excellent accommodation characteristics enablesmultiple antenna–spacecraft bus combinations. Spacecraft accommodation issuesmay arise from restrictions on either the spacecraft bus or the launch vehicle, or fromother spacecraft functions. With any of those limitations, the system implementationmay adversely affect antenna gain and C/I performance. Any performance restrictionsultimately affect the system’s profit-generating potential through reduced capacityand increased satellite and terminal costs.

Gen*Star Goals

TRW’s Gen*Star line of antennas was developed to surmount all current limitations ofolder MBA designs. The Gen*Star antenna is a new MBA design that enables serviceproviders to supply the highest gain and highest C/I coverage anywhere in the full-earthFOV. The Gen*Star antenna design is based on design and development that began in1995 (Figure 3). Over the past six years, TRW has developed the innovative Gen*Starantenna concept into a mature, proven technology. A major focus was our evaluation ofalternative antenna approaches suitable for the densely tiled narrow-spot-beam architec-tures needed by emerging Ka-band systems [2–5]. The Gen*Star antenna goal, now

Table 1. Major planned Ka- and V-band MBA satellite constellations using multiple-spot-beam coverage

Cyberstar

Euroskyway

East

WEST

SPACEWAY™

Celestri

Aster

GESNc

a

b

c

V-Stream

CyberPath

Astrolink GEO 5 Population centersanywhere

Ka

GEO North America,Europe, Asia

Europe, Africa,Middle East

Europe/Africa

–

GEO

GEO

GEO/MEO

GEO/MEO

GEO/MEO

GEO

GEO/MEO

GEO

GEO

3

5

12

9

16 36–

–

5 25–

19

12

10

Europe, Africa,Middle East

Population centersanywhere

–

–

–

–

Ka

Ka

Ka

Ka

Ka

Ka/V

SystemSatellite

Orbit CoverageFreq.BandNumber

BeamSize(deg)

BeamNumber MarketAntenna

0.8

1

1

0.6

0.6

1

58

96

72

32

Horn-fed

64

24

Horn-fed

V

V

V

V

–

–

–

–

–

–

–

–

–

–

Horn-fed

Horn-fed

Horn-fed

Horn-fed

–

–

–

–

–

Multimedia Full

Infrastructure

Multimedia

Multimedia

Multimedia

Infrastructure

Infrastructure

Infrastructure

Infrastructure

–

–

Baseband

OnboardProcessing

Baseband

Baseband

Baseband

Baseband

–

–

–

–

–

GEO = geosynchronous Earth orbit. MEO = medium Earth orbit.

WEST = Wide-Band European Satellite Telecommunication.

GESN = Global Extremely High-Frequency Satellite Network (licensed to TRW).

b

a



Figure 3. Gen*Star antenna development timeline

Figure 2. Representative patterns show relative sources and levels of interference



realized, was to provide uniform beam performance (similar peak gain, pattern shape, sidelobes, and cross-polarization) over the entire Earth in a single satellite [6–9]. No currentsystems, not even MBA, can match that performance, as they can provide only• A smaller coverage area with a single satellite• Significantly degraded performance for the full-Earth FOV, using a single

satellite• Full-Earth-FOV coverage using multiple satellites

In contrast, various trade studies have shown Gen*Star’s coverage to be limited only bythe number of beams supported by the available spacecraft power.

Gen*Star Antenna System Design and Performance

The Gen*Star antenna system includes multiple reflector assemblies in which beams aremultiplexed among the reflectors, typically according to operating frequency bandassignment, in a four-reflector, four-color reuse factor. Figure 4 shows a typical group ofinterleaved beams and their mapping to a set of four reflector assemblies. The frequencyand polarization mapping is usually either a fourfold frequency-reuse factor (higher-trafficareas) or a sevenfold frequency-reuse factor (lower-traffic areas), selected to minimizeinterference. Color-coding of the beams identifies which beams belong to which fre-quency and polarization combination. In Figure 4, a classic frequency and polarizationselection, defined as seven-color, is mapped with the beam distribution among the fourreflectors.

The Gen*Star antenna system’s uniqueness and major benefits stem from its ability tocover the entire earth from geosynchronous orbit with the same performance that previoussystems provided in only a regional area. Yet the Gen*Star antenna is small enough tostow for launch in a very compact space. We have conducted several trade studies toidentify the optimal reflector geometry, rating those benefits highest in our selectioncriteria.

Figure 4. Beam and frequency mapping to multiple reflector assemblies:Colors map to reflectors and numbers map to frequencies

3 4 5 6 7

1 2 3 4

3 4 5 6 7 2 3 4 5 6

4 5 6 7 1 3 4 5 6 7

2 3 4 5 6 1 2 3 4 5

6 7 1 2 3

5 6 7 1 2

1 2 3 4 5 7 1 2 3 4

2 3 4 5 6 1 2 3 4 5 7 1 2 3 4

3 41 2

6 7

5 63 46 74 5

4 52 3 2 37 1

31 2 75 6

53 4

4

4

5

7

6 5

71 6

1

5

7

17

23

1

6

6

Reflector 4

Reflector 3Reflector 1

Reflector 2



The four best candidate reflector geometries, detailed in Figure 5, were selected andanalyzed for performance: a single-offset reflector, a single-offset reflector with a splashplate, and both top-fed and side-fed Cassegrain reflectors. The single-offset reflector—thesimplest candidate—can be easily stowed but required a very long focal length to achievelow scan loss. The single-offset reflector with a splash plate is a folded equivalent to thesingle-offset. It packages into a smaller volume but still delivers inadequate performance.The preferred designs are the remaining two candidates, top-fed and side-fed withmultiple reflectors, which have excellent scan loss characteristics due to high magnifica-tion factors.

Another trade study, focused on spacecraft packaging, examined five candidate reflectorgeometries (Figure 6): a single-offset, an offset Cassegrain, an offset Gregorian, a top-fedCassegrain, and a side-fed Cassegrain. Overall, the performance comparisons show thescan loss improvement possible with top-fed/side-fed reflector geometries when alldesigns are constrained to fit in a common packaging volume. Again, the single-offsetreflector can be easily stowed but has serious scan limitations, owing to its constrainedfocal length. The offset Cassegrain and Gregorian reflectors proved marginally better butstill inadequate for a full-Earth FOV. The remaining two candidates with folded opticreflectors again show superior scan loss because they can achieve large focal-length-to-diameter (F/D) ratios in a small volume.

The top-fed and side-fed geometries both deliver outstanding performance. However, theside-fed option proved superior because it• Stows more compactly• Offers the added benefit of low-profile stowage characteristics• Maintains low side lobes and low cross-polarization• Delivers wide-angle scanning with consistent high gain across the entire Earth

(because of its large F/D ratio)

Previous MBA systems produced beams with gain diminishing and patterns broadening asthe scan angles increased beyond 4 deg; the Cassegrain curve shows main beam distortionstarting around 3 deg (Figure 7). Such spreading results in higher side lobes, asymmetricbeam shape, and higher interference to neighboring cells. Yet the Gen*Star antenna designprovides high gain, along with stable low side-lobe and low cross-polarization patternslittle affected by changes in frequency at scan angles beyond 8 deg (Figure 8).

To validate the selection of the side-fed dual-reflector option for Gen*Star, a developmen-tal reflector assembly was built and tested in TRW’s near-field scanner (Figure 9).Precision range measurements were taken for the Gen*Star preproduction unit. Themeasured patterns correlated to the analytic predictions and did indeed show excellentperformance: uniform gain and negligible change in beam shape over the full-earth FOV.

Gen*Star Antenna Flexibility

The Gen*Star antenna architecture is highly flexible. The configuration can be easilycustomized for a specific mission requirement. The foremost enablers of Gen*Star’sflexibility are• Standardized components. Feed assemblies, hinges, launch locks, reflectors, deploy-

ment booms, etc.• Ability to use any polarization or combination of polarizations. Right-hand and left-

hand circular polarization (RHCP, LHCP), horizontal (H), vertical (V), elliptical



• Frequency insensitivity. Multiple frequency bands accommodated in the samesystem: C-band, X-band, Ku-band, V-band, etc.

• Compact stowed system. Packaging and configuration options are significantlyincreased on various spacecraft whose antenna is virtually independent of the bus orreduces occupied spacecraft real estate on the nadir deck

• Switched beam. Enables bandwidth-on-demand to be achieved for higher-trafficareas, yet flexibility allows coverage of lower-demand areas

Figure 5. Performance comparison of four reflector geometries with sizeunconstrained: Top-fed and side-fed with multiple reflectors are preferred



Figure 6. Performance comparison of five reflector geometries with sizeconstrained: Top-fed and side-fed are again preferred



Figure 7. Gain variation of Gen*Star antenna aperture superior to that ofCassegrain/Gregorian designs

Figure 8. Gen*Star antenna’s side-lobe and cross-polarization patterns showinglow sensitivity to frequency and scan angle

Gen*Star’s flexible architecture maximizes reuse of component designs. Besides loweringdevelopment costs, standardization of components allows the same horn to be used in anyposition, whereas other architectures require design of a different horn for every position.Gen*Star thus uses coverage changes to reduce hardware changes. In fact, Gen*Star’suplink assemblies are scaled versions of its downlink assemblies. The only nonstandardelements in the antenna system for different customers are the feed clusters, which areunique to given coverage areas. Another Gen*Star innovation is the ability to configurefeed clusters for a superset of beam locations early in the production schedule, so thatcustomers can specify the final configured coverage pattern late in the program cycle.



Figure 9. Developmental Gen*Star antenna aperture in near-field range testing

Both linear (H and V) and circular (RHCP and LHCP) polarizations have been measuredto confirm flexibility in polarization. Circular polarization showed nearly 30-dB cross-polarization response, and linear showed in excess of 35-dB. For either type of polariza-tion, the system produces very low interference to or from neighboring cells. In fact, anypolarization or combination of polarizations per ground cell location is possible.

Another key feature is the antenna system’s ability to support other frequency bands. Itslong focal length allows multiplexed-frequency-band feeds to be integrated. Configura-tions have been developed that provide outstanding spot-beam performance at Ka- andKu-bands simultaneously.

The Gen*Star antenna also has excellent stowage features. The side-fed, dual-reflectorsystem stows naturally in a compact configuration, using a patented double-deploymentscheme. Such compactness in stowage enables many mounting options on variousspacecraft buses.

Two primary configuration options are available:• A top-mounted antenna suite with easy accommodation to the top of the spacecraft

bus—the configuration currently in flight production.• A side-mounted configuration, which reduces waveguide runs and thus increases

effective isotropic radiated power (EIRP). The use of a dual-frequency feed to reducethe number of apertures, along with side-mounting to the spacecraft bus, may benefitcustomers with challenging spacecraft or launch vehicle accommodations.

The top-mounted Gen*Star antenna (Figure 10) has eight dual-reflector multiple-beamapertures (four uplink and four downlink) that multiplex spot beams into contiguousground coverage areas. The top-mounted configuration enables very simple integrationonto the nadir-facing surface of the spacecraft bus. Four apertures for each frequency



Stowed Deployed

band permit optimal performance and coverage in a region of densely packed cells. Eachreflector assembly is independent and individually stows into the compact space of a 4-mfairing. The top-mounted antenna system was in flight production for the Astrolinkprogram. To validate assembly and integration techniques for the top-mounted Gen*Starantenna, we used flight components and processes to develop the Antenna IntegrationSimulator (Figure 11), a single quadrant of a full-up antenna system.

Some satellites have limited space available on the nadir face of the spacecraft bus. Inthose cases, the folded-optics design, which is very compact, naturally accommodatesmounting on the side of the spacecraft. That configuration allows staggering of the feedtrays, which opens many more routing options from traveling-wave-tube amplifiers. Theresult is minimal waveguide length, minimal waveguide loss, and maximal EIRP. Replac-ing the transmit feed clusters with dual-frequency feeds produces only slightly degradedcoverage performance, even when just four reflector assemblies are used (Figure 12). Thedual-frequency apertures can mitigate the risk of uplink-to-downlink (UL-to-DL) cover-age misalignment.

Additional benefits of the side-mounted antenna are its lower satellite center of mass,lower volume, and easier accommodation of the antenna on the spacecraft bus. Theincreased bus compatibility and low antenna volume enable more flexibility in launchvehicle, allowing the service provider more freedom to select the launch vehicle bestsuited to a given program. Alternatively, a larger reflector system can be employed ineither system to produce increased gain in each beam area. In fact, either system can beconfigured with fewer apertures, with some tradeoff in performance (Figure 12).

Studies reveal many configurations are possible (Table 2), each with advantages anddisadvantages with respect to size, weight, complexity, and performance. In an eight-aperture configuration, the radio frequency (RF) components are very simple, each beamis independent of all others, and no downlink power couples directly into the uplinkreceive channels. Seven apertures would enable larger feeds, but that configuration wouldrequire all DL-sized apertures and combined UL/DL frequencies to be in the same feed.With six apertures (three UL, three DL), the reflectors grow in size because of reducedfeed size and degraded side-lobe performance. With four apertures (four combined UL/DL), coupling between frequency bands becomes an issue for the feed assembly thatsupports both bands. With three apertures (three combined UL/DL), aperture size must be

Figure 10. Gen*Star top-mounted spacecraft configuration



Figure 11. Gen*Star Antenna Integration Simulator used to validate assembly andintegration techniques

Figure 12. Side-mounted Gen*Star antenna configuration

Dual-frequency feedsenable commonapertures for bothtransmit and receive

Optics, scaled dimensions,materials, and fabricationprocesses identical to thoseof top-mounted antenna

Side-mounted for lowermass and lower satellitecenter of mass

Staggered antennalayout for maximalEIRP

UL and DL Feed Clusters

Antenna Integration Simulator:Tooling Provides 0-Gravity Aperture Locations



increased significantly, frequencies are combined, and performance is reduced. With twoapertures (one UL, one DL), aperture size approaches twice the original, and multipleelements must be combined to control the illumination. Finally, a single-aperture configu-ration would face all of those issues. A key study result showed that weight does notincrease in direct proportion to the number of apertures.

Pointing is a coverage performance issue. For equivalent performance, beamwidth mustincrease with the pointing error. If desired, closed-loop tracking, based on a UL beaconsignal in each aperture, can improve on-orbit pointing.

System Advantages of Gen*Star Antenna

The Gen*Star antenna is designed to deliver the high performance necessary to supportmultibeam Ka-band systems. The result is the first antenna to offer excellent gain and C/Iperformance anywhere in the full-Earth FOV.

Excellent C/I Performance. A significant advantage of the Gen*Star antenna is itsexcellent C/I performance, which permits maximal capacity. In many MBA systems,capacity is limited by interference rather than noise. To minimize interference, coveragepatterns must be designed to reduce interference to acceptable levels. Typically, optimiz-ing the coverage pattern to reduce the C/I ratio increases the separation between coveragecells and reduces the number of copolarization-interfering channels. The net result is adecrease in system capacity. With the Gen*Star design, service providers can both spacecoverage cells densely and optimize the coverage pattern for maximal capacity. Maximiz-ing capacity translates directly into service revenue and profit for the satellite serviceprovider.

Uniform High EIRP and High G/T Ratio. The excellent scan performance of theGen*Star antenna translates into uniform high EIRP and a high gain-to-temperature (G/T)ratio for all coverage cells. That uniformity enables standard antenna terminal design,which in turn minimizes terminal cost and thus increases the affordability of the system tothe end user.

Table 2. Aperture selection affects aperture size and feed sizes

7

6

4

3

2

1

8 Small Single

7 DL aperturesSmall–

Medium

Medium+

Medium+

Large

Large

Dual

Number ofApertures Aperture Size Feed Size Description

Single/DualFrequency

Large–

Small–

Medium–

Medium+

Medium+

Large

Single

Dual

Dual

Single

Dual

Small+

3 UL and 3 DL larger apertures

4 UL and 4 DL apertures

4 DL slightly larger apertures

3 DL large apertures

1 UL and 1 DL oversized apertures

1 DL oversized aperture



Full-Earth FOV. A full-Earth FOV minimizes time to global coverage. The ability of theGen*Star antenna to provide high-performance coverage over the full-Earth FOV reducesthe number of satellites required for global coverage, allowing the service provider toreach global coverage with fewer launches in less time. The improved time to market andreduced launch costs may translate into higher revenue and profit for the service provider.

Coverage Flexibility. Coverage flexibility offers the service provider high-valueapproaches to service rollout, sparing, and service restoration. Homogeneous gain andside-lobe performance over the full-Earth FOV translate into high levels of coverageflexibility. The Gen*Star antenna uses that flexibility to provide multiregion and multislotcoverage. The multiregion antenna system has beam coverage designed for operationfrom one orbital slot that can cover multiple regions. The multislot antenna system hasbeam coverage designed for two or more orbital slots that can cover the same or multipleregions [10,11,12]. After launch and deployment, the beams selected for the initialcoverage rollout are activated, while the remaining feeds stay dark until the serviceprovider desires to change or redistribute the activated beams to another preconfiguredcoverage area.

With the addition of beam-switching networks, the ultimate goal of bandwidth-on-demandcan be realized. Selected beams can be multiplexed to provide the longest dwell in thehighest-traffic area, yet retain accessibility to lower-demand regions.

Multiregion/multislot coverage capabilities give service providers the option of high-value approaches to service rollout and sparing. With the ability to cover multiple regionsand service multiple slots, the provider has much greater flexibility in deployment. Ratherthan customizing the satellite for a specific coverage area, the provider can select multiplecoverage options and postpone the final selection until launch. That additional flexibilityallows the service rollout to be based on the latest market data.

Multiregion/multislot coverage capabilities also permit high-value sparing and servicerestoration approaches [11,12]. Rather than expensive one-for-one sparing, the serviceprovider can configure spares to support multiple regions. For example, a spare can fill infor a failed spacecraft, providing the same coverage. Sparing requirements can be reduceddramatically, depending on the coverage requirements and available orbital slots. Inaddition, the spare satellite can be either dark or configured to supply additional capacity.If another spacecraft fails, capacity can be reallocated as necessary.

Low-Risk Design. The Gen*Star antenna is a mature design that offers high performancewith very low levels of risk to the satellite service provider. Satellite coverage has beenexpanded from national to regional and global markets (Figure 13) with high-qualityservice to all. The Gen*Star design has been verified, with all manufacturing processeshaving been proved with the Antenna Integration Simulator. It is now qualified for flight.

Flight Performance

The first-flight configuration (Figure 14) has been built and tested. Performance measure-ments (Figure 15) verify the excellent performance in side-lobe and cross-polarizationlevels that enables Gen*Star to provide high C/I performance in dense-coverage areas.Finally, the pointing error achieved through the alignment process has delivered unprec-edented accuracies (Figure 15).



Figure 13. Gen*Star expands previous national satellite coverage to full-Earth FOV

Figure 14. Protoflight configuration: Gen*Star top-mounted flight unit in rangemeasurement

–8.8 –7.2 –5.6 –4.0 –2.4 –0.8 0.8 2.4 5.64.0 7.2 8.8

Earth Field of View (deg)

Sca

nL

oss

(dB

)

National

Regional

1

0

–1

–2

–3

–4

–5

Global

Gen*Star Coverage Gain

Cassegrain/Gregorian Coverage Gain

Flight Hardware Being Alignedin Near-Field Range

Satellite with All AperturesAligned to Same Reference



Summary

TRW’s Gen*Star family of precision high-gain satellite antennas offers the expandingcoverage required in the Ka-band market. Providing superior performance, flexibility, andcapacity, along with a full-Earth FOV, the Gen*Star antenna is the clear choice for high-capacity applications. Performance results of the protoflight model exceed those previ-ously shown for other designs. This family of antennas has many flexible design features,so it can meet future market demands. In addition, TRW’s long experience in the design,integration, and testing of Ka-band antenna products for government customers enables itto offer a mature but high-performance design with very low levels of risk to the satelliteservice provider.

The authors salute the tremendous efforts of Louis Wilson, whose constant vigilance inthe pursuit of perfection enabled the antenna system to perform beyond anyone’s expecta-tions. Shady Suleiman’s key contributions to the feed development likewise enabled the

Figure 15. Gen*Star flight antenna performance surpassed expectations



outstanding system performance. The diligence and hard work of the mechanical team andintegration and test team members resulted in an extraordinary piece of hardware.

References

1. M.E. Bever et al., “Advanced Broadband Satellite Digital Communication System forthe Emerging Ka-Band Market,” TRW’s Technology Review Journal, Vol. 9, No. 2,Fall/Winter 2001, pp. 1–18.

2. S. Nguyen et al., Deployment of Dual Reflector Systems, U.S. Patent 6,124,835,September 26, 2000.

3. A.L. Peebles et al., Compact Side-fed Dual Reflector Antenna System for ProvidingAdjacent, High Gain Antenna Beams, U.S. Patent 6,211,835, April 3, 2001.

4. C.W. Chandler et al., Compact Offset Gregorian Antenna System for ProvidingAdjacent, High Gain, Antenna Beams, U.S. Patent 6,236,375, May 22, 2001.

5. C.W. Chandler et al., Compact Front-fed Dual Reflector Antenna System for Provid-ing Adjacent, High Gain Antenna Beams, U.S. Patent 6,215,452, April 10, 2001.

6. J.A. Hudson, “Off-Axis Performance of Shaped Antennas at Millimeter Wave-lengths,” Radio Science, Vol. 24, No. 4, July/August 1989, pp. 417–426.

7. C. Dragone, “Unique Reflector Arrangement with Very Wide Field of View forMultibeam Antennas,” Electronic Letters, Vol. 19, 1983, pp. 1062–1063.

8. R. Jorgensen, P.P. Baling, and W.J. English, “Dual Offset Reflector for MultibeamAntenna for International Communications Satellite Applications,” IEEE Trans.Antennas Propag., Vol. AP-33, 1985, pp. 1304–1312.

9. G.W. Collins, “Shaping of Subreflectors in Cassegrain Antennas for MaximumAperture Efficiency,” IEEE Trans. Antennas Propag., Vol. AP-21, 1973, pp. 309–313.

10. C.W. Chandler et al., A New Generation of Broadband Communications SatelliteAntennas, American Institute of Aeronautics and Astronautics, 20th InternationalCommunications Satellite Systems Conference, Montreal, Canada, May 2002.

11. C.W. Chandler et al., Broadband Satellite Communications Antenna Technology forthe Emerging Ka-Band Market, 7th Ka-Band Utilization Conference, SantaMargherita, Liguria, Italy, September 2001.

12. C.W. Chandler et al., Advanced Satellite Antenna Technology for the Emerging Ka-Band Market, International Astronautical Federation Conference, Toulouse, France,October 2001.



Charles W. Chandler, a senior staff antenna engineer inTRW Space & Electronics’ Engineering, Antenna RF Engi-neering Department, currently heads Independent Researchand Development (IR&D) projects devoted to the design anddevelopment of antennas. He was the Astrolink payloadantenna system engineer lead at TRW, responsible fordeveloping, prototyping, and producing commercial antennasystems that meet the requirements of the global broadbandprocessed payload market. Previously, at the NationalAeronautics and Space Administration’s (NASA’s) JetPropulsion Laboratory, he was the SeaWinds antenna systemengineer lead, responsible for developing and producing anantenna for active scatterometry. Before that, he characterizedand analyzed antennas for deep space missions. He has over22 years of experience in the development of advancedantenna systems. He holds 14 U.S. patents. He received a BSin physics from Florida Institute of Technology.

[email protected]

Leonard A. Hoey, a TRW Space & Electronics Six SigmaBlack Belt, is currently working on an engineering processcontrol and improvement project. During the past five years, inEngineering’s Antenna Product Center, he has focused on theAstrolink antenna, the Gen*Star development project, andvarious IR&D and new business activities. He most recentlyserved as the deputy lead for the Astrolink antenna integratedproduct team. Previously, he held project management anddesign lead positions on a variety of commercial communica-tion satellite projects. He holds one U.S. patent. He received aBS in mechanical engineering and material science engineeringfrom the University of California, Berkeley.

[email protected]



Ann L. Peebles, a senior staff antenna engineer in TRW Space& Electronics’ Engineering, Antenna RF Engineering Depart-ment, is currently focused on antenna design and developmentfor the Advanced Extremely High Frequency antenna project.Previously, she was the responsible design engineer for theAstrolink uplink antenna system. She designed and patentedthe Astrolink Dual Reflector Antenna System and was the testleader of the Astrolink Development Verification Model. Shehas also been involved in a variety of IR&D projects. Beforejoining TRW in 1995, she cofounded Innovative Research &Development Company, where she served as a senior scientist,developing millimeter-wave and far-infrared test equipment.Previously, she focused on antenna development for a varietyof commercial satellite systems. She holds five U.S. patents.She received a BS, MS, and PhD, all in electrical engineeringand all from the University of California, Los Angeles.

[email protected]

Makkalon Em, a hardware engineer in TRW Space & Elec-tronics’ Engineering, Antenna RF Engineering Department,focuses on the design, analysis, and simulation of antennasystems for the Astrolink Ka-band satellite communicationsystem. His responsibilities have included the development ofsoftware analysis tools and microwave hardware. Currently, heis designing radiating elements for phased-array antennaapplications. Before joining TRW in 1997, he studied energyand electromagnetic systems, with a focus on backscatteringradiation from photonic band-gap structures. He holds threeU.S. patents. He received both a BS and an MS in engineeringfrom the Massachusetts Institute of Technology.

[email protected]

advanced antenna technology for a broadband ka-band … · 2017-12-16 · 2010. trw’s gen*star...

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