Antenna design, analysis and measurement techniques

An artist impression of the Olympus satellite in orbit
Artist's impression of Olympus in orbit

“Our main areas of expertise are design and analysis of space-borne reflector antennas with associated feed systems and planar waveguide arrays. This includes also the investigation of unwanted scattering between the different structures and antennas on a spacecraft, compact antenna test range design and near-field measurement techniques as well as probes for near-field measurements”, says Niels Christian Albertsen, Managing Director of TICRA.

“These tasks require software development, and over the years we have produced an extensive software library that forms the basis of our commercial program packages which are sold to antenna manufacturers and institutions all over the world.”

TICRA, a relatively small Danish SME company, has managed to increase its business from single contracts with the European Space Agency (ESA) to numerous customers, mainly from outside ESA Programmes. TICRA was founded in 1971 by three employees of the Electromagnetic Institute, Technical University of Denmark. Since then it has established itself as one of the leading consultancy companies for spacecraft antenna analysis.

Simple and complex contoured beam example
Simple and complex contoured beam example

Today the staff of TICRA includes 11 engineers, all specialists in electromagnetics, physics or computational antenna theory and methods. Based upon the experience gained from working with ESA, TICRA has managed to establish a worldwide network of customer’s including international organisations such as INTELSAT, INMARSAT and EUTELSAT.

Another impressive achievement, reached in close collaboration with the Technical University of Denmark, is the development of the SNIFTD (Spherical Near-Field Transformation) software, which has the ability to correct for the influence of the measuring probe during testing of antennas. The SNIFTD is now used at antenna test facilities throughout the world.

Collaboration with ESA has played an important role in TICRA’s consolidation as a European space enterprise. “We are grateful to ESA for the cooperation in the early days, because it gave us the opportunity to establish the international contacts that are vital to a company with few domestic customers”, continues Albertsen.

“Due to our modest size and flexible organisation, we are able to respond quickly to our customers' demands and many companies have realised that it is cost effective to use TICRA to solve specialised antenna problems. Our customer base today extends worldwide, from the Far East to India, Europe, and North and South America.”

For more than 20 years TICRA has been the principal commercial provider of antenna design and analysis software tools to the space community. In recent years these software tools have been upgraded by TICRA to include modern Graphical User Interfaces (GUI) which are now mandatory in commercial software. ESA is supporting TICRA with this upgrading to modern GUI, which is in line with the latest ESA standards.

Participation in ESA satellite programmes

Artist's impression of the Planck spacecraft
Artist's impression of the Planck spacecraft

As early as 1978 TICRA participated in the development of the Olympus satellite under contracts with ESA and British Aerospace. Albertsen says: “calculations on different possible antennas on the Olympus satellite were performed by TICRA. We designed and did the initial analysis for the dual elliptic coverage of Italy, the degradation of the Telemetry and Tele-Command (TT&C) antenna pattern caused by the antenna farm structures and the telecommunication reflectors. The solar panels were analyzed in 1982 and in 1983 the performance of a special fill-in antenna, placed on the rear side of the satellite and operating simultaneously the main TT&C antenna, was calculated. This special fill-in antenna actually rescued the Olympus satellite later on.”

Since then TICRA has been involved in many other ESA satellites, including ERS-1, First, MSG (Meteosat 2nd generation), XMM, Metop and Planck, the latest ESA project in which TICRA has been, and still is, involved.

In 1998/99 TICRA carried out its first contract under the ESA SME initiative: “Development of a General Preprocessor System for Antenna Design Programs”. Recently TICRA started its second SME contract with ESA: “Integrated Software Tool for Design, Analysis and Optimization of Planar Waveguide Arrays”. Both contracts are aimed at providing existing computer programs with state-of-the-art GUI, following ideas and techniques whose development has been fostered by ESA over the past 10 years.

TICRA and Planck

Payload horns and feed system for the Planck satellite
Payload horns and feed system for the Planck satellite

The ESA satellite Planck is the 'time machine' astronomers will use to travel back towards the beginning of space. Planck will be launched in 2007, its ultimate goal will be to help astronomers to decide which of the theories explaining the birth and evolution of the Universe is correct and which need to be discarded. Several elements on the Planck satellite have been designed and analyzed by TICRA under contract to the Danish Space Research Institute.

Albertsen points out: “the Planck satellite works in the terahertz range and its development is opening new fields for us. The dual reflector antenna design and the position of the detector horns were determined by TICRA in 1996, and the radiation patterns from all horns were calculated both for ideal conditions and with simulated reflector surface errors. These analyses have continued for different designs and surface distortions up to now.”

Future outlook and business opportunities

Dual Gridded Reflector System
Dual Gridded Reflector System

Until now, the majority of spacecraft antenna designs have concentrated on the frequency range from 1 to 40 GHz, but future scientific missions are now planning telescopes for use in the Terahertz range. These will need extremely large antennas in terms of wavelengths and new techniques are needed to analyse them correctly.

As part of the Planck project for ESA, TICRA has developed a new geometrical theory of diffraction ray-tracing technique for multiple reflectors and integrated this into the commercially available GRASP8 package. Albertsen is very satisfied that TICRA had the opportunity to work with ESA on the Planck project. This new experience of working on the Terahertz range for the Planck project should provide TICRA with new commercial opportunities in the future.

Analysis of dual reflector system
Analysis of dual reflector system

Another important growth area is ground-based antenna systems. While space applications used to be the only driving factor of TICRA software development, ground-based antennas are now becoming important. “Today our capabilities extend to the analysis of beam-wave guides with many reflectors used as feeds for large antennas. Refined models for the support struts found in these ground-based systems have also been developed. We see increasing opportunities to expand the ground-application area over the coming years.”

Software sales constitute a greater portion of TICRA’s turnover today. Albertsen concludes, “good graphical user interfaces, in combination with the Internet, offers new and exciting possibilities. Therefore, many activities at TICRA are devoted to topics such as Java programming, client/server applications and object-oriented programming techniques. By allocating the necessary resources to stay up-to-date on these subjects while maintaining the expertise within electromagnetics accumulated in the company over many years, we are convinced that we will be well equipped to meet the challenges of the future.”

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