Site: ANT Bosch Telecom
ANT Nachrichtentechnik GmbH,
Gerberstrasse 33
D-7150 Backnang
Germany

Date Visited: June 23, 1992

Report Author: N. Helm

ATTENDEES

NASA/NSF:

C. Bostian
M. DeHaemer
P. Hager
N. Helm
R. Jennings
C. Mahle
E. Miller

HOSTS:

Dr.-Ing. Gerhard Ohm

Director Engineering, Space Communications Systems

Presenters

L. Friederichs

Communications Systems

H. P. Petry

Antennas, Space & Ground

K. H. Hubner

TWTAs, EPCs

A. M. Khilla

Solid-State Amps, Microwave Signal Processing

F. J. Glandorf

Mixers, Modulators, Oscillators, LNAs

D. Rosowsky

Multiplexers

T. Weismann

Optical Transmitters/Receivers, and Ground Station Equipment

E. Auer

Digital Modems

BACKGROUND

ANT is owned by Bosch and is part of the Bosch Telecom Group. ANT Bosch Telecom is a major manufacturer of telecommunications, television and cable products with annual sales of about $1.2 billion, with the ANT Space Division providing about $100 million. Approximately 15% of annual sales is spent for research and development.

In addition to ANT Space Communications Systems, a subsidiary of ANT, TELDIX, is also active in space systems. The TELDIX Company, located in Heidelberg, is a supplier of stabilization gyroscopes, solar drives and other high-precision electro-mechanical hardware. TELDIX was not visited, and thus is not covered in this report.

Since 1970, ANT has supplied quality space hardware to German, European, American and international programs. ANT contributed mainly to INTELSAT IV and INTELSAT VII, SYMPHONIE, EUTELSAT 1 and 2, TV-Sat, TDF, DFS-KOPERNIKUS, TDRS, ANIK B, METEOSAT, TELECOM II, HISPASAT, and CCS (China).

ANT is a manufacturer of high quality hardware that is based on well-understood production techniques. New technology is introduced into its product lines in small steps, usually as refinements to improve performance in an already established product. The space-qualified EPC provides an excellent example of the way ANT developed and improved a product that currently holds the record in its class for the most years of reliable space operation.

RESEARCH AND DEVELOPMENT ACTIVITIES

Communications Systems

ANT has an advanced technology program for development of space and telecommunications systems and products. One prime technology area covers transmit amplifier designs, developing improvements in power, efficiency and linearization in TWTs and EPCs, along with the increased use of field effect transistors (FETs) into higher power and frequency domains.

In the advanced system and payload area, ANT is developing an ambitious OBP system with a modular on-board switch. A satellite employing this system could serve as a switching, signalling and network synchronization node with a throughput capability of several Gbits/sec. It would use multibeam TDMA in the up-link and one TDM carrier per beam in the down-link.

Antennas

ANT produces antenna products for both space and ground systems. The space antennas include spot, scanning spot, shaped and contoured beam antennas as well as multifeed, reconfigurable and frequency scanning elements. Technology areas include structural elements, shaped reflector and deployable reflector antennas, waveguide and feed technologies including rotary joint, corrugated feed and direct radiating array developments.

ANT has recently completed a study and breadboard hardware of shaped dual offset reflector antennas (Cassegrainian and Gregorian) for prescribed aperture distributions, sidelobe suppression and cross-polarization optimization including a feed system development. The study also covered contoured and flat-topped beam applications. A recent study for INTELSAT on frequency-addressable antenna technologies, especially for VSAT mesh networks, recommended two design concepts favorably, a passive direct radiating array and a multifeed parabolic cylindric reflector antenna.

A large internal R&D program is underway that will develop reconfigurable and adaptive antennas, multibeam reflector antennas, direct radiating arrays, including beam-forming networks, and feed technology developments.

The ground antenna developments include VSAT products for rapidly growing networks in Eastern Europe. ANT used new sophisticated CAD methods to shape the main and sub-reflector antennas on its 2.4 m Ka-band ground antenna. The result is 80% efficiency at 29 GHz.

Traveling-Wave Tube Amplifiers

A new space-qualified 110 W TWTA was developed for the HISPASAT program. ANT acquires the tube from AEG or from other vendors, and integrates it with its own EPC system. ANT officials stated that amplifiers like the 250 W TWTAs used on TV-SAT and TDF are not likely to be required again for some years, but that the 110 W size will be specified for many new medium/high powered satellites, and will become the standard for TV broadcast satellites in Europe and perhaps other geographic areas as well.

Current EPC development is concentrated primarily on mass, size and cost reduction by employing new digital circuit concepts and advanced technology such as ASICs and SMT.

Solid-State Amplifiers

In the area of solid state amplifiers ANT presently uses microwave integrated circuit (MIC) technologies but has a development program to develop MMIC technologies. MMICs show great promise for power amplifiers above 10 GHz and also for phased array applications where high reliability and packaging density are important. During the tour of the development laboratory, we were shown a number of solid-state devices including a 4 GHz MESFET power amplifier family with output powers of 10, 20, 30 W along with a linearized version with an output power of 13 W. A 1.3 GHz power amplifier employing 20 W MESFET devices has been developed for ESA's ARTEMIS Program and provides output powers of 5, 10, 20, and 40 W, on telecommand. Another example of transistor amplifier applications is a channel amplifier and a linearizer family for S- to Ku-band.

Mixers, Modulators, Oscillators and LNAs

Several development efforts were discussed, including the design and performance of millimeter wave oscillators at 36.5 GHz and 44.5 GHz employing "whispering gallery mode dielectric resonators" using commercially available HEMTs. High output power (>7 dBm) and efficiency (10%) have been achieved for both oscillators. Improved HEMTs, along with additional theoretical work to analyze the coupling mechanism of whispering gallery modes, will increase performance as millimeter wave power generation requirements reach to and beyond 100 GHz. Present development activities include X-band QPSK modulators for COLUMBUS and a C-band receiver for Inmarsat III.

Multiplexers

A demonstration model of a 12-channel contiguous-band output multiplexer (OMUX) operating at 12 GHz was presented. Advanced CAD techniques along with significant advances in microwave filter design were required to complete this multiplexer, which was built to flight hardware standards. The model was tested and found to verify computer simulations and demonstrated excellent performance. Testing included driving all 12 channels (eight 27 MHz and four 54 MHz) at 50 W. The Ku-band multiplexer design builds on OMUX experience gained in programs such as INTELSAT IV, TV-SAT, TDF, TELEX-X, DFS-KOPERNIKUS, EUTELSAT 2 and TELECOM II, for which ANT has designed, manufactured and qualified a multitude of filters and multiplexers at frequencies from C- to Ka-band. Included in these developments were OMUXs at input power levels up to 450 W per channel.

Optical Transmitters and Receivers

Development efforts have been ongoing for ESA on its SILEX program. ANT's role in the development of the communications subsystems includes the laser driver, laser diode transmitter and receiver package, including the front-end and a quadrature pulse position demodulator. All of these communications packages have been breadboarded and put through an extensive test program. These development efforts will support future European programs such as the DRS, COLUMBUS and HERMES.

Digital Modems

ANT developed a Universal Satellite Modem for INTELSAT that is compliant with INTELSAT's International Business Services (IBS) and Intermediate Data Rate (IDR) satellite services, as well as with many domestic satellite systems. The modem is fully programmable from 64 to 8,448 kbits/sec using variable sampling rate decimation and interpolation algorithms which allow for the operation of the digital modem with all specified bit-rates, without any hardware adaption. A fully digital CMOS chipset consisting of four ASICs has been developed integrating the complete functionality of a digital QPSK demodulator.

SUMMARY

In summary, ANT has an active product-oriented research and development program that primarily directs the R&D efforts to specific product development or improvement. Much of ANT's expertise is, therefore, in the staged development of its product lines (which consist of layer on layer of proven products) with small, well-defined improvements in these products. This method of development results in high reliability and low training requirements since its assembly line changes slowly with small steps. The result of this R&D philosophy is that one sees only in limited areas new and exciting activities in its plant. However, one often is impressed by the efficiency of the R&D efforts that result in a high quality line of complementary products.

ANT officials stated that its internal requirements for quality and reliability made its products relatively expensive. Therefore, ANT has been underbid by companies in Japan, North America and Europe that deliver a lower quality product. ANT officials felt that the requirements and specifications for high quality space components and products are being reduced. One measure that ANT has instituted in recent months to become more efficient is to combine their production and engineering divisions.


Published: July 1993; WTEC Hyper-Librarian