Site:                Institute of Mobile and Satellite Communication Techniques (IMST)
                      (German name) Institut fur Mobil- Und Satellitenfunktechnik GmbH
                      Carl-Friedrich-Gauss Strasse2
                      D-47475 kamp-Lintfort

Date Visited:  26 April 1999

WTEC Attendees: Dennis Friday (report author) T. Itoh, L. Katehi, R. Pickholtz

Hosts:            Prof. Dr. Ingo Wolff, President, IMST and Rector, Duisburg University
                     Dr.-Ing. Mattthias Rittweger, Head of Department, RF Circuits and Systems
                     Dipl.-Ing. Johannes Borkes, Head of Department, Integrated Circuits and Systems
                     Dr. Ing. Dirk Heberling, Head of Department, Antennas
                     Will Chr. Will Hildering, Head of Department, Systems


IMST provides central engineering, test, and development resources for the wireless, telecommunications, and information technology industries. Customers include almost all of the major European wireless and telecommunication companies as well as companies throughout the Far East and Pacific, and Israel. The intellectual resources at IMST include expertise in both the systems and the hardware aspects of communications and information networks with a special focus on mobile wireless technology, both terrestrial and satellite-based. Its wide-ranging technical programs include component and systems engineering design, theoretical and experimental analyses, and special test and measurement services.

IMST President, Prof. Dr. Wolff, graciously served as the WTEC panel's host. The people it primarily interacted with were the IMST equivalent of the board of directors, which included Dr. Wolff and all four Department Heads. Dr. Wolff presented an overview of IMST, its history, its funding profile, its organizational structure, its technical programs, its staff profile, its customers, and its goals. His presentation was followed by more program-specific presentations by two of the four Department Heads. They talked about wireless systems architectures, RF hardware design and performance, and antennas for wireless applications.

The formal presentations were efficient summaries of the relevant IMST programs, and were enriched with off-the-viewgraph insights, peripheral discussions, and open and informative replies to the many questions from the WTEC team. The two-way interaction was intense and they adapted their agenda accordingly, but there was much more to discuss than the panel had time for, constrained by the need to travel from and to Frankfurt that day. Two of the department heads, with programs of interest to panel members did not give formal presentations because of limited time, however they did participate in the discussions, and the panel was given a condensed but comprehensive tour of the IMST laboratory facilities. Overall, the visit was very productive.


IMST management referred to the organization as a workbench facility for the wireless telecommunication and information technology industries. Special focus is on mobile and microwave communications techniques for industrial applications, and much of the work is related to technology development and evaluation for next-generation personal cellular/mobile communications hardware and systems. Their economic niche is the gap between relevant cutting-edge research and industrial product development. IMST helps companies bridge this gap by partnering with industry and performing the generic research and engineering development work necessary to accelerate product development. This effort in turn reduces the risk to industry in new commercial ventures. In addition to its primary role as a gateway between research and commercialization, IMST provides a broad range of expert technical services to industry, performs measurements to characterize antennas and other components, develops and carries out specialized training programs for industry, designs and fabricates special prototype hardware and software products for industry, and even carries out market research studies for new systems.

The institute is a private, non-profit corporation (designated GmbH in German). The laws governing a non-profit corporation in Germany are different from those in the United States. Most significant is the fact that if a German company declares itself non-profit, at least 50% of its income must come from the government, or it will not be recognized as a non-profit organization and be taxed as a for-profit company. However, IMST, due to its special role as both a national resource and a key facility that will help the Duisberg region attract high technology industries to compensate for their declining coal and steel industries, receives special dispensation from this requirement. The IMST mission is to serve industry and to derive most of its funding from the private sector. As a result of rapid growth in only a few years, and the excellent reputation acquired, approximately 80% of funding comes from the private sector, and 20% from publicly-funded R&D projects. Without special treatment as a non-profit company, IMST's programs would suffer financially. Otherwise, IMST pays taxes like any other company. The success of IMST can be measured by steady growth ever since it was formed, to over DM10 million of business in 1999.

Dr. Wolff told us that he and the four other managers present at the meeting, and the Vice President, assume all the technical and financial responsibilities for the operation of IMST. They pointed out that, unlike in the United States, the person who carries out all the legal work for the corporation is also an engineer by training. Professor Dr. Ingo Wolff's commitment of time was especially significant since the panel learned that, in addition to his position as President of IMST, he had recently been appointed Rector of Duisburg University (equivalent to chancellor of a university in the United States) and was embarking on a major restructuring within the university.

The IMST laboratories are located on a rural 10,000 m2 site a few kilometers across the Rhine from Duisburg. The buildings contain 4,500 m2 of space, of which 1,500 m2 is laboratory space. The laboratory space includes a 300 m2 clean room and several electromagnetic anechoic chamber facilities for antenna characterizations, electromagnetic compatibility measurements, and related wireless technology experiments. The building cost was DM12 million, and the total investment was DM17.5 million. Construction began in 1992, and the institute began operation in January 1993. IMST presently has 87 employees from 15 countries, including 68 engineers and scientists. IMST also maintains a close working relationship with the University of Duisburg, and a total of 40 students work at IMST from there and from other universities. Staff size has been approximately constant since early 1996.

The organizational structure is straightforward, consisting of an administrative branch and four departments. Dr. Peter Waldow, Vice President of IMST, is responsible for operation of the company. He has responsibility for central services, marketing, legal issues, technology transfer and intellectual property, quality assurance, finances, and general administration. The four departments are Systems, Integrated Circuits and Systems, RF Circuits and Systems, and Antennas & Electromagnetic Compatibility (EMC). Overviews were only given by the Systems and the Antennas and EMC Department Heads. The others were present throughout the meeting and participated in discussions.

The Systems Department, under the direction of Will Hildering, is responsible for communications networks and systems, satellite systems, wave propagation, mobile systems, signal processing, and digital electronics. The Antennas and EMC Department, under Dr. D. Heberling, is responsible for antenna performance and characterization, EMC analysis and evaluation, and the interactions of human systems with electromagnetic fields and wireless equipment. The RF Circuits and Systems Department, under Dr. M. Rittweger, is responsible for electromagnetic modeling and simulation of devices and circuits, the design and development of radio frequency (RF) circuits, modules, and printed wiring boards, and hybrid microelectronics. The Integrated Circuits and Systems Department, under Dr. J. J. Borkes, is responsible for applications specific integrated circuits (ASICs), integrated communications circuits, RF circuits, and related measurement techniques. Only two of the departments provided overviews, and the division of responsibilities was not clear where there appeared to be an overlap.

IMST leverages its resources by partnering with industry, standards, and professional organizations. These include ETSI, the UMTS Forum, the UMTS Development Partnership, ITG, FGF, IMEC, IMAPS, the University of Duisburg, and other groups. They also are ISO 9000 accredited and maintain an ISO 9001 Quality System. They market worldwide by partnering with international technical marketing agencies. Customers include many of the key telecommunications companies in Europe and Asia.


IMST is active in a broad range of technical programs focused on both the physical and architectural/algorithmic aspects of wireless systems communications. Emphasis is on mobile communications and 3rd Generation (3G) wireless technology. The role IMST plays in enhancing the development and competitiveness of European and Asian wireless technology is significant. IMST serves as a central laboratory resource for independent technology development, for reliable measurements, for impartial performance evaluations, and for industry training and leadership. The main technical programs will be summarized in the following paragraphs.

Antennas and Antenna Characterizations

Antenna design and prototyping is one of the services provided by IMST. The activity in this area ranges from pure research for maintaining cutting-edge competence, to, for-contract, application designs, the latter comprising mainly mobile radio antennas and microwave satellite communications antennas. Although antenna design was not a strong component of the briefings, the WTEC study team did visit some of the related laboratories and see some prototypes. The antenna design challenges for handheld units were for innovative designs fully integrated with the geometry and space-location constraints of the handset. The designs also incorporated information gleaned from antenna-human interaction studies. There was also some work on integrated antenna-RF front ends. In addition to their design expertise, IMST researchers are very strong in providing antenna characterization support for industry. Their antenna measurement facilities are of high quality and used for characterizing a broad range of antennas for both terrestrial and satellite communications. One is an indoor facility and the other is an outdoor range. The WTEC panel only visited the indoor range due to time limitations, but received a description of the outdoor range and viewed it from a distance.

The indoor antenna measurement laboratory is a totally shielded 8 x 12 x 5.5 meter facility used in two modes, as a near-field facility and as a far-field facility. It is lined with pyramidal absorber and has a useable frequency range from 400 MHz as a near-field facility (800 MHz as a far-field facility) to 50 GHz. The measurement apparatus is a 2.5 x 2.5 meter automated planar near-field scanner procured commercially. As a near-field facility it is used primarily for determining pattern, polarization, and gain properties of high gain antennas used in satellite or long terrestrial links; and as a far-field facility, it is used for pattern and polarization characterizations of electrically small, high frequency, low gain antennas used in hand-portable or vehicular-mobile telecommunications applications.

The outdoor facility is a standard far-field range with a 110 m separation and a 23 m source tower. The main applications are for characterizing pattern and polarization of physically larger and heavier antennas ranging from low frequency antennas down to 50 MHz, to high frequency, high gain antennas up to 18 GHz. There is also a mobile tower and a satellite-to-ground capability when longer baselines are required.

Studies of Human-Antenna Interactions

IMST also has an antenna program that focuses on the effects of the human user on the handset antenna pattern, RF front-end and propagation, and also on the EM field patterns in the human body, particularly the head. The latter is for evaluating and designing for compliance with European EM exposure regulations. IMST also has a well developed experimental and theoretical program for developing complete and realistic models of the electromagnetic fields inside the human body and around the human user of a mobile telephone handset, as compared to the handset in isolation. The research includes developing accurate electromagnetically equivalent models of the typical human body at frequencies of interest and performing accurate measurements of field patterns.

IMST has unique experimental facilities dedicated to modeling the effects of the human body on air link performance. This work has several aspects. One is directed toward a standard measurement configuration for comparing the performance of different handheld phones. A standard human replica artifact was developed by combining simple geometric forms into a circularly symmetric saline-filled standard human researchers call Charlie. The performance of different handheld units, both prototype and commercial, are studied and compared by placing them adjacent to Charlie's head and rotating Charlie in an anechoic chamber containing a receiving antenna that can scan vertically. The frequency range for this work is 10 MHz to 6 GHz. IMST offers a service for determining realistic radiation characteristics and specific absorption rates in the human body based on this model and is working with ETSI to standardize the procedure.

Researchers also developed another facility for performing measurements to determine human-body effects on antenna and system performance and for use in modeling. The apparatus consists of a basin with a surface contour corresponding to the right half of the human torso, oriented vertically. The basin may then be filled with fluids that mimic the approximate electromagnetic properties of the human body at various frequencies. If a handset is placed under the basin near the ear, then this design enables the field patterns to be measured inside the head, or elsewhere in the body for biological studies and for modeling effects on antenna performance. A precision computer controlled 6-axis robotic arm is used for precisely positioning electromagnetic field probes on a spatial grid of points inside the fluid medium. The probes can measure both the electric and magnetic near-fields of the transmitting antenna over a frequency range of 10 MHz to 3 GHz in fluid and up to 6 GHz in air. This facility is called the Dosimetric Assessment System, or DASY. This facility is used for compliance tests for exposure limits as well as for optimizing new antenna designs. Software modeling services are provided that link with these measurements.

Environmental Reliability Validation

IMST also has a range of peripheral services for evaluating the reliability of the designs in normal use. It provides a sort of one-stop shopping lab for its customers' essential needs. There are electrodynamic shaker facilities and a time-variable-temperature chamber for testing components and systems under vibrational and thermal stress. Parameters such as voltage, current, frequency, power, spectrum (to 40 GHz), and bit error rate are monitored during the environmental stress test to assess performance. Poor reliability can negate any superior electrical performance in a commercial wireless product. The facilities are set up specifically to test communications systems with coax and wave-guide connections to the unit under test.

Software Development and Services for Wireless Design and Modeling

IMST also performs the research and the software development necessary to produce and market a collection of software packages for wireless design and modeling. One of the software products and services is a full wave 3D FDTD PC program for solving Maxwell's equations. Called Empire, it has special wireless-design oriented features for modeling RF microcircuitry as well as antenna performance and human body effects. There is also a software package for nonlinear modeling of FETs called TOPAS that has been incorporated into HP's EEsof design and simulation software package. MEDEA is a system for the design of Silicon ICs incorporating thermal and electromagnetic constraints, while improving reliability and reducing costs. Coplan is a new design and simulation tool for design of coplanar waveguide (CPW) MMICs. It is integrated with HPs EEsof and the user can perform simulations and optimization for GaAs designs up to 67 GHz. Customers can purchase the packages, but IMST staff can also provide solutions for the customer, as well as use the software for internal research.

Characterization of Active Wireless Components

IMST provides measurement services for a wide range of wireless and microwave technologies. IMST has well-developed laboratory facilities for characterization of devices, circuits, and components. The different measurement systems are used for internal research and development projects and are also used to provide complete measurement services for external customers. Some of the systems and related software are offered for sale. The total program provides a wide variety of measurement capabilities and services for both linear and nonlinear characterizations.

The following is a summary of capabilities:

IMST has developed its own methodology and instrumentation for characterizing various nonlinear properties of devices, circuits, and systems for one-port, two-port, and three-port configurations. Some of these capabilities are not commonly available and may incorporate unique analysis methods. This is also an active research program for new techniques. These methods are available for on-wafer (coplanar geometry), microstrip, and coaxial lines. Unfortunately we did not see their microstrip measurement techniques.

The following are some of the specifications for harmonics and intermodulation products:

Electromagnetic Compatibility Design and Assessment

IMST has extensive expertise in both modeling and measurements for characterizing electromagnetic compatibility of radio/wireless products. Modeling software and experimental facilities include an anechoic chamber. These capabilities are used to perform research, as well as to provide customers with data and with test services to determine whether product emissions satisfy U.S., international, and E.U. trade compliance regulations. IMST is on the U.S. FCC list of approved facilities for certification of specific absorption rate for handheld products headed for the U.S. market. EMC compliance of all electronics/wireless products and official recognition of test facilities are significant issues in wireless for the global market.

Design and Prototyping

IMST provides services for design and prototyping of RF devices and RF front-ends. Excellent RF design software is available, both in-house developed and commercially available software. Capabilities include CAD, simulation, optimization, and EM field simulation for RFICs, MMICs, ASICs, hybrids, and communication systems. It has complete clean room and GaAs fabrication facilities (300 sq. m - class 100 to 10,000) for developing prototype devices and systems. IMST is very active in this area. Some of the projects include the following:

Overall this effort comprised a significant portion of the activity, and IMST demonstrated a successful history of having designed and developed the RF sections, and other components, for many successful radio products manufactured by well-known international electronics/wireless companies in both Asia and Europe.


IMST is, by its mission, and the work it engages in, forward looking. The projects all reflect the cutting-edge technology for commercial products. IMST's brief history combined with its growth and successes speaks for its capabilities. In short, IMST appears to be well embedded in the enabling technologies underlying the worldwide wireless industry, and its management and technical staff are competent and in a good position to observe major trends and assess emerging technologies. Programs address important problems in the wireless industry. For example, in addition to GSM refinements, IMST is active in UMTS, DECT, and general 3G and 4G issues. The current focus, with the exception of satellite technology, is almost totally terrestrial, portable, and mobile.

IMST sees the wireless industry evolving as essentially mobile technology embedded in adaptive architectures and believes that the mobile economy will expand astronomically. IMST researchers stated that Europe is not interested in LMDS for Europe, just as a possible product to sell abroad wherever it is marketable. As a result, it is not receiving much attention and no energy is being expended in this area with respect to standards activities or R&D as happened on GSM or is now happening on UMTS. No one believes that a market exists in western Europe for LMDS systems or services in western Europe, because there is already a hard-wired infrastructure that will meet all European needs. IMST researchers also aren't convinced that the performance of broadband wireless systems at 30 MHz frequencies will be superior to wired broadband systems or to advanced mobile systems.

The broad but focused range of programs covers virtually all hardware aspects of wireless. Many of the designs exhibited were straightforward but well executed. Other designs reflected innovation and experimentation. The centralized wireless-focused design, device prototyping, software services, test and measurement services, and products provided are clearly an asset to customers, and enhance competitiveness. While the WTEC panel saw no great departures from conventional technology, IMST is a key facility and a lab to watch. Two examples of programs that best reflect cutting edge thinking and planning are the nonlinear circuit and device modeling and characterization project and the elaborate theoretical and experimental program to assess the interactions of the handset antenna and the human user and model the effects on propagation, RF circuitry, and field levels in the body. The significance of these projects is the contributions they will make to aspects of wireless design that are presently only partially characterized. Devices in handheld units are always operating in or near saturation to optimize battery life and the design process to optimize the nonlinear behavior is a black art. Propagation paths can degrade 3 to 5 dB when the typical GSM phone is placed near the head, and other wireless units have exhibited 8 to 10 dB degradation in the hands of users. These are important programs and important wireless issues.

Published: July 2000; WTEC Hyper-Librarian