REPORT ON THE OPEN COMMISSION MEETINGS (BUSINESS MEETINGS)
Chair: Prof. V. Scuka (Sweden)
Vice-Chair: Prof. Masashi Hayakawa (Japan)
The URSI 25th General Assembly was held in Lille, France during the period of August 28 to September 5, 1996. The GA was very successful due to the great efforts of the local organization, Past Commission E chair (Prof. Scuka), session chairs etc. In the following I include the reports of Commission E sessions and several joint sessions (reported by session chair(s)).
E1.1 Dusty Plasmas, Meteorologic-Electric Environment and EHD
reported by H. Kikuchi
The session was exclusively devoted to new areas above and 9 invited papers were actually presented as follows, though two papers were cancelled because of unavailability of speakers:
The quality of papers were all extremely high, dealing with new theories, concepts, approaches, and developments in the field of dusty and dirty plasmas for extraterrestrial and terrestrial meteorologico-electric environments with noise and chaos as well as for laboratory with industrial applications, although not going into details for each paper owing to limited space. However, it should be noted that theories, concepts, and method presented in the present session and in accompanying Session E1.2: Self-Organization and Chaos in Meteorologico-Electric Environment are being applied to a broad area of radio, geo- and astro-physical sciences, for instance as presented in other sessions such as HEG: EM Coupling between the Ground (Including Seismic Activity) and the Upper Ionosphere and Magnetosphere.
The most important thing for a session is neither the number of papers nor audiences, but the qualities of papers. In order that the URSI may maintain a high scientific standard and become a nucleus to create and develop new sciences through interdisciplinary and multidisciplinary joint work, a couple of this kind of sessions should be continued.
E1.2 Self Organization and Chaos in Meteorologico-electric
Environment
reported by S. Moiseev
To my opinion, Session E1.2 has been successful with a large number of participants. More than 30 persons took part in this session. As a result, some contacts will eventually lead to joint works, such as, e.g. my contacts with scientists working in Mexico. Six invited talks were presented and two additional talks could not be presented due to the lack of financial support for contributors. One more contributor could not come due to personal reasons.
Session E1.2 has demonstrated importance of simultaneous study of chaos and order and of interaction between chaotic and regular structures. Namely due to this interaction, anomalies in behaviour or transport coefficients arise: reduction of coefficient of turbulent viscosity and anisotropy of heat transfer (in the latter case directions with reverse heat transfer exist). This problem was analyzed in the talk of S. S. Moiseev. The talk by G. C. Dijkhuis also analyzed a problem of partial regularization of small-scale helical turbulence during the process of its interaction with large-scale structures. The second problem intensively discussed in the session was the importance of the role of electromagnetic processes in evolution and diagnostics of natural hazards. For example, in the talk of H.Kikuchi it was shown that electrohydrodynamic vortices (EHD vortices) can be substantially stronger than HD vortices. The talk by N. Erokhin and S. Moiseev discussed a number of electromagnetic precursors of tropical cyclones and the talk by H.Branover analyzed an influence of helicity on spectra of turbulence and on electromagnetic waves propagation. It was shown that the role of helicity is very important.
It is necessary to include a similar session again in the program of next URSI General Assembly.
E2.1 Terrestrial Electromagnetic Environment
reported by
A. P. Nickolaenko
This session was organized by M. Hayakawa and A. P. Nickolaenko. The reports delivered at E2.1 session may be divided into the following groups.
Closely related objectives of the investigations were the reason why the audience in the sessions E2.1, E2.2, E3, HG2, and HEG was mainly the same. This conditioned fruitful and efficient exchange of opinions and noticeable progress in understanding old and formulating update problems.
At the poster session the most interesting works were ## 2, 3, and 12. Following topics were presented in the reports:
To our opinion, the most promising directions of the studies are: - Modifications of the ionosphere by electromagnetic radiation of natural sources (including source and disturbance location), and - Seismogenic electromagnetic and environmental phenomena (including modifications of the ionosphere and magnetosphere).
E2.2 Electric Discharges from Cloud-top to the Ionosphere
reported by
Z-I. Kawasaki
In Session E2.2 (Electric discharges from cloud-top to the ionosphere) we have 14 papers. Seven of them are invited papers, and the rest are contributed. The main subject of this session is the electric discharges from a thundercloud top to the ionosphere as the session title shows, and twelve papers among 14 are related to the session subject. One of the rest dealt with Laser Triggered Lightning Experiment in the field and the other showed the mechanism of the initiation in the cloud which causes positive cloud to ground discharges empirically. Though these two papers are interesting, the participants are especially eager to discuss and change ideas for revealing the physics of red sprites, blue jets and ELVES. More than 70 scientists joined this session and hot discussions werse held.
Following is the historical background of the topics. During the summer campaign in U.S.A which was held in 1994 they succeeded in taking video pictures of quite interesting phenomena, which seemed to be discharges from thundercloud tops to the ionosphere. Some of the lightning physicists have been believing that such a kind of phenomenon should exist, but there were no scientific evidence before this campaign. These phenomena are named Red sprites and blue jets after their color of visible emissions. One year after the campaign the other phenomenon named ELVES is also discovered, which is also the visible light emission in the lower ionosphere. Many of the related scientists were impressed very much on the captured data sets, and the big and exciting discussions to understand the physics and/or mechanisms were held in several conferences and workshops. The conveners believed that the URSI activity should present the contribution on this new interesting subject, and we have convened this session.
Boeck reviewed the history of research activity of the discharges to the ionosphere. He also presented the satellite video picture of both ordinary lightning discharges and ionospheric discharges, and the results show the less common tendency of ionospheric discharges near the equatorial region.
Nickolaenko showed a theoretical idea of lightning discharges as a heater of the lower ionosphere. He mentioned that the non-linear effects in the plasma of lower ionosphere is related to the phenomena called Red sprite and Blue jet.
Inan showed the effects of lightning discharges on the ionosphere empirically. He newly designed the photo diode array with photo multiplier to detect weak emission and conducted field experiment in 1996. He found the part of the luminous emission was propagated in the radial direction with velocity of light, seeming to be against the theory of relativity.
Sentman reviewed the campaign which was mentioned as the origin of this current topics. He introduced the red sprites and blue jets, and also introduced the optical spectra of red sprites. He concluded that the spectra are similar to those of aurora, and showed the red color of sprites to be due to the first positive bands of molecular nitrogen. He showed the propagation speed of ELVES at lower ionosphere empirically, and the estimated velocity faster than that of light still remains as a puzzle to struggle.
Pasko proposed a physical model of Blue jets as a streamer type process occurring on atmospheric spatial scales. He carried out the numerical simulation for his proposed model, and showed that blue color of jets is an emission from the second positive band of molecular nitrogen. It was also shown that jets are not necessarily associated with lightning discharges to the ground, and may appear only in relatively rare cases of large thundercloud charge accumulated at higher altitudes than 20 km.
Dowden showed the evidence of cloud-top to ionosphere electrical discharges by measuring the VLF subionospheric signals. His estimated channel resistance of red sprites implying the discharge time constant should be about 20 ms, and it is consistent with observed results for sprites.
Nickolaenko introduced a new technique to locate the source of ELF pulses or Q-bursts. According to his understanding red sprites are eventually associated with Q-bursts, and it is necessary to make the location of the source clear for further understanding red sprites.
Sukhorukov proposed a blue jet model as an upward discharge. It can explain the dynamics of blue jets, in particular the remarkable consistency of the observed vertical velocity of jets.
Petrova showed the physical mechanism of discharges from cloud-top to the ionosphere. It can be understood as a usual leader discharge formation and development by the charges distribution inside the thundercloud.
Cho presented the computer simulation of red sprites and blue jets. They calculated the electric field structure between the ground and ionosphere at an altitude 100 km. Their results are similar to Pasko's numerical simulation results.
Brundell showed the observed results of the VLF signal associated with cloud-ionosphere discharges and Hale presented the theoretical idea of the coupling of electrical energy to the ionosphere.
As we can see through this session, we have many observation results and phenomena of red sprites, blue jets, and ELVES. However the discussion of their mechanism is undergoing, and the physical understanding is not ready to us.
E3 Planetary Lightning and Related Phenomena
reported by
W. J. Borucki
Eight papers were presented by authors from five countries; France, Germany, Japan, Russia and the United States. The titles and authors are as follows;
1. "The Planetary Electric Generator and Lightning in Global Electric Circuit" by P. A. Bespalov and Yu. V. Chugunov. They reported an electrodynamic model of the global current produced by a planetary generator and thunderstorms. The planetary generator is modeled as a nonsolid rotation of a magnetized planet - plasma envelope system and the thunderstorm are represented by a current generator in the atmosphere. They found that coupling between the atmosphere and magnetosphere has an important influence on the global electric circuit.
2. "A Ground-based Search for Optical Lightning on Venus" by S. A. Hansell and D. M. Hunter. These authors described a new technique that promises to allow ground-based observers to study lightning occurring on other planets without the necessity of sending a spacecraft to the planet. Basically, they observe the occasional presence of lightning flashes. Further work is required to verify their preliminary results.
3. "Lightning-generated Whistlers and Related VLF/ELF Emissions in the Jovian Magnetosphere" by Y. Hobara, O. A. Molchanov, and M. Hayakawa. These researchers reported their investigation of the propagation of whistlers in the magnetosphere of Jupiter. They find that magnetospheric temperatures must be near 20 eV and that the radio frequency power must be 10$^{2} \sim$ 10$^{5}$ Watts per flash in the 0 to 20 k frequency band.
4. "Spectral Irradiance Measurements of Simulated Lightning in Planetary Atmospheres" by W. J. Borucki, C. P. McKay, D. Jebens, and H. S. Lakkaraju. Results were presented of laboratory work that simulated planetary lightning by forming a 20,000 degree K plasma with a pulsed laser. The measurements showed line and continuum radiation by atomic and ionic species and that the spectra from various planetary atmospheres is likely to be quite different from one another.
5. "On the Possible Occurrence of Sprites in Other Planetary Atmospheres" by D. D. Sentman. The recent discovery of completely new classes of lightning discharges in the Earth's atmosphere named "Blue Jets" and Red Sprites" was described and predictions about what we might expect on other planetary atmospheres was explored.
6. "Measurements of Radio Frequency Wave in Jupiter's Atmosphere" by K. Rinnert, L.J. Lanzerotti, G. Dehmel, F. O. Gliem, E. P. Krider, and M. A. Uman. The first probe to enter the atmosphere of Jupiter carried low frequency radio equipment to measure the number of flashes, their direction and their waveforms. The authors described their experiment and the very puzzling results they obtained. In particular, the waveforms and the power spectra are unlike those of terrestrial lightning. Although no quantitative interpretation is available yet, they believe the lack of a solid surface changes the waveguide properties of the atmosphere and thereby influences the waveforms of the received signals.
7. "Evidence for the Presence of Lightning in the Clouds of Venus" by J. M. Grebowsky. Over the years a great deal has been written about attempts to detect the presence of lightning activity on Venus and characterize its properties. Measurements from the Russian entry probes show the much impulsive radio noise, but optical and whistler searches have produced much more ambiguous results. The latter work has shown that the earlier results were too optimistic. Dr. Grewbowsky discussed the new developments in analyzing the whistler data and discussed how those signals generated in the ionosphere can be distinguished from signals from lightning.
8. "In-sit Investigation of Planetary Atmospheric Electricity" by R.Grard. Dr. Grard is working with the Principal Investigator of the Huygens entry probe, Prof.M. Fulchioni, to complete and validate an instrument to measure the electrical properties of the Titan atmosphere. This instrument is now undergoing ground-based tests and will shortly be carried by the Cassini mission to Saturn.
The wide range of topics covered in the session meant that the audience received a picture of the entire research field. Theoretical work, ground based experiments, recently completed space missions and instruments being developed for future missions were covered. Lightning occurring on both Earth analogs such as Venus as well as lightning occurring on the largest planet in our solar system was addressed. Because each of the investigators is doing new and original work, the audience received up to date information on the research areas being actively pursued. The audience showed its appreciation and later, when the authors were available for individual discusions. Approximately sixty people attended.
In the future it would be helpful to hold each session in a room that had solid walls and a ceilling rather than simple cloth enclosures. These walls were so thin that they allowed the sound from many different sessions to intermingle. This change would increase the ability of the audience to hear both the speakers and the questions that the audience asked.
E4 Spectrum Management and Utilization
reported by R. D. Parlow and
R. G. Struzak
Introduction
Sub Committee E4 on Spectrum Management and Utilization was formed to provide information on the use and management of a natural resource, the radio spectrum. It was also intended to provide a bridge between the scientific community that conducts radio science research and the developers of modern telecommunication systems as well as those that manage the radio frequency spectrum. This activity is important in that there is much interdependence between these three communities. This year's general assembly afforded another opportunity to present information on topics of current interest.
Overview
The session included ten papers and covered a variety of topics which included:
Within the context of the papers important information was presented which indicated the important trends and issues associated with the spectrum management community. Key points were that there continues to be phenomenal growth in the number of radio users and a host of new and innovative wireless applications. This has made the radio spectrum more congested and has forced more complex sharing and interferences situations. A number of approaches for dealing with this ever more complex situation were presented. Of particular interest was the approach that Europe is taking upgrading the associated regulatory environment. Europe is making a concentrated effort to harmonize their spectrum use, to develop coordinated positions regarding the implementation of new technologies and to present a common approach within the activities of the International Telecommunications Union.
With the rapid introduction of digital technologies and the proposed use of low earth orbit satellites (LEOS), there are many new domestic and global telecommunication applications that will be introduced in the near future. Two such applications were included in the session, one of which described how low cost broadband services can be provided using LEOS. This was particularly interesting because of the low cost projections, simplicity regarding link initiation and the high capacities that appear possible. A second paper described the use, application and superior performance of Code Division Multiple Access (CDMA) technology for voice and low capacity data in a specific LEO satellite system scheduled for launch in 1997. Key points of the paper included methods for efficient power control, high efficiency vocoder designs, spot beam antenna utilization and system management approaches that enhance communications reliability.
Two papers were presented that dealt with broadcasting issues. The first described European planning associated with future deployment of digital audio and digital techniques but many questions remain regarding the mature of the service as well as spectrum availability and sharing issues. A second paper presented some very interesting automated methods that provide more efficient spectrum planning and station assignments in the VHF and UHF TV bands.
Finally, papers presented information concerning the 1995 World Radio Conference and its implications on future wireless telecommunications development and regulatory structures, the use of ITU propagation models for radio service planning, and concerns raised regarding the survival of passive and scientific radio services in the face of ever increasing commercial satellite systems development. All of these topics are of crucial importance to the scientific and applications community as they portray many of the difficult issues that must be successfully addressed if the explosive telecommunications revolutions is going to progress at a rapid pace. The concerns of the scientific community are of particular concern because of the potential interference that many of these new commercial applications may cause to their associated radio services.
Observations
The goal of building linkages between the traditional URSI community and the world of spectrum management as well as the associated telecommunications development community remains important. It is particularly important because of the explosive global growth in wireless telecommunications systems that have significant financial, political and trade implications.
The session participants expressed significant interests in the overall topic as well as the issues and information presented in each of the papers. There were many questions which illustrated their understanding of the issues and the importance of the subjects in general. There were approximately 60 participants in the session representing a broad cross section of experience and interests.
One area of concern was the number of papers that were assigned to the session. The session chairman scheduled eight papers but two were added by the organizing committee. This made it almost impossible to have an effective presentation and leave any time for questions. It is suggested that each session have a least 20 minutes for each presentation taking into account the time spent during the coffee break. Also care must be taken to keep the number of parallel session having common interest to a minimum.
Overall, the conduct and organization of the Lille General Assembly was outstanding --- the organizing committee should be congratulated.
E5 High Power Electromagnetics
reported by R. L. Gardner
Session E5, High Power Electromagnetics, was organized by R. L. Gardner and C. E. Baum and consisted of the following papers:
Paper 3 was not presented. The remainder of the papers were well attended. The first half of the session had attendance of about 60 people and by the last half the attendance had dropped to about 30. I choose to interpret the attendance change to interest in the first half on the sessions. A High Power Electromagnetics session is clearly appropriate. However, the lethality aspects for HPE are more interesting than the more esoteric high power microwave source work.
E6 Electromagnetic Topology for Electromagnetic Interference Analysis and Control
Unfortunately, the report on this session is not available.
E7 Coupling to Multiwire Cables
reported by F. Canaver
* Analysis of the papers
In this session, seven papers were presented. All authors were present, and the presentation took place in the order planned in the Conference Programme.
The first paper by V. Cooray dealt with "an overview of the interaction of lightning generated electromagnetic fields with power lines", and there was an interesting discussion of the validity of simplified models to predict the effects of lightning on the conductors of power lines. In particular, the case of finitely conducting ground was discussed.
The second paper by Bermudez et al. presented a comparison of numerical calculations and measurements made under a EMP simulator. This result constitutes a good validation of the theoretical approaches commonly employed to predict the effects of electromagnetic fields to open-air transmission lines.
The third paper by Christopoulos scholarly discussed the differences of the "separated solution" vs. "integrated solution" for the field coupling to multiwire lines. In the first approach the field and wire problems are loosely coupled, while in the second approach the wire description is an integral part of the field problem. The shortcomings of the first approach are evidenced in closed environments with resonances, and the numerical difficulties of the integrated approach are discussed.
The fourth paper by Kasdepke and ter Haseborg, analyses the current distribution in complex cable harnesses created by shielded and unshielded multiconductor transmission lines as well as coaxial cables.
The last three papers deal with field interactions with shipboard power cabling, underground cable systems and printed circuits tracks, respectively. The interest of this session was triggered by the complementarity of the first three papers which showed the benefits and shortcomings of the theoretical models currently used for field coupling problems.
* General Comments
The first issue which I would like to raise is related to the attendance to this session: although well qualified members were present, the total number of attendees (approximately 20) was definitely low. In my opinion, the major cause for this lack of presence is related to the title and content of this session, which is perceived by the general audience as a too basic and too theoretical one. The EMC community tends to be more oriented towards applied works. This tendency was recently exacerbated by the strong markets needs, related to new EMC regulations (e.g. in Europe). Therefore, a suggestion for the future could be to find a more appealing title for this section (for example, "Modeling of Radiated Immunity"), or to do it in conjunction with Commission B, whose audience is more familiar with theoretical subjects. The second issue to be discussed is the acceptance of invited vs. contributed papers. Based on my experience, I am strongly in favour of invited papers, which ensure (if properly chosen) good presentations and interesting topics. I believe that the spirit of URSI is better met by a session where the presentations discuss and review a subject from various point of view, than by a session where each author reports on his latest results. As a matter of fact, I must say that I experienced some difficulties in deciding whether to include a contributed paper in the session, based on the short abstract which is required by URSI standards, and I am not sure I always made the best choice.
E8 Susceptibility of Electronic Devices or Equipment to High Amplitude Electromagnetic Interference
reported by V. Scuka
The session was attended by more than 60 participants. The lecture room was fully occupied.
All six papers have been presented orally. The papers dealt with the electromagnetic interference and radiation from microstrip lines and printed circuits boards. Two papers considered the electromagnetic impulse degradation of ICs and considered the new proposals to investigate these effects on the ICs.
One paper was deeply considering the simulation of dynamic "hand-metal" ESD used for susceptibility testing.
The papers have been lively discussed, however the discussion was time limited by the acting chairman of the session.
The quality of the presentations was varying, however most of papers were original and attracted high interest in the audience. So the session was very satisfactory from the scientific point of view.
Special encouragement should be given to the "young scientist" from Belarus who succeeded in performing his research successfully in spite of very difficult conditions at his university.
The session followed strictly the time schedule.
EA Electromagnetic Compatibility and EM Pollution
Unfortunately, the report on this session is not available.
EB Field Propagation and Coupling to Structures
reported by
F. M. Tesche and M. Ianoz
Oral papers: 9
No-shows: 1
Posters : 2
Canceled posters 1
Oral papers vs. posters : 9 to 1
Estimated number of participants :50.
There were no very excited controversial discussions but interest for all the presentations has been shown by questions or remarks after each presentation.
The main lines of interest for the research activity coming out from the presentations delivered at the session are :
EF Radio Noise and Interference above 30 MHz
reported by J. Gavan
The conveners of the session were Dr. A. J. Grasiewski from the Georgia Tech Atlanta USA and Dr. J. Gavan from the CTEH Holon Israel.
In the session 4 papers were presented. The authors of two papers:
The first presentation was:
The second Presentation was:
The third presentation:
The fourth presentation:
The joint session E/F includes 4 interesing lectures about innovative and up-to-date subjects dealing with noise and interference (Commission E) and propagation and remote sensiong (Commission F). The importance of these subjects increases significantly for the scientists and radio engineers due to the tremendous growth in mobile radio ground and satellite systems and the increase of passive and active remote sensing systems in the microwave frequency ranges.
The small number of participants (in comparison with about 100 participants on similar subjects at the EMC Symposia at Wroclaw and Rome) could be increased by choosing a better timing of the session and not introducing sessions dealing with similar subjects at the same time.
EK Characterization of Electromagnetic Sources and Design of Equipment for Minimum Coupling with the Human Body
Unfortunately, the report on this session is not available.
AE Electromagnetic Metrology Applied to EMC
Unfortunately, the report on this session is not available.
CE Electromagnetic Interference to the New Generation of Digital Radio
Systems above 1 GHz
reported by Dr. Kobayashi and B. Despres
1) General information
The session was organized in the last afternoon of the URSI General Assembly ; for this reason, the attendance was rather limited : approximately 20 persons were present. Six papers were presented so that the time schedule was not difficult to hold, allowing for good discussions after each presentation. As an introduction to the session, I presented a short summary of the standardization activities within CISPR (International Special Committee on Radio Interference) on the subject under discussion.
2) Prospects of electromagnetic compatibility for accommodating new digital wireless communication systems - T. Kobayashi
The paper contained a description of the characteristics of the telecommunication systems to be protected, a description of the mechanisms of digital systems to cope with interference (taking the example of the Japanese new PHS system) and finally some results of BER (bit error rate) degradation induced by microwave ovens (operating at 2.45 GHz) on the PHS (operating at 1.9 GHz). It constituted an excellent introductory paper to the session, explaining in details all the aspects of the problem understandable for people not fully experts of the subject.
One question was raised on the protection mechanisms of radio systems.
3) Statistical measurements of electromagnetic disturbance from microwave ovens and interference with digital radio systems - Y. Yamanaka and T. Shinozuka
The paper was presented by Dr. Kobayashi. After explaining the operating principles of microwave ovens, it presents the results of experiments in Japan to study the effect of microwave ovens on the Japanese PHS system. Presented results show that the APD (amplitude probability distribution) of the emission correlates closely to the induced BER degradation of the radio system link ; for this reason APD is proposed as a good estimator of the interference potential of an interfering source.
Questions and more global discussion followed on the possible utilization of this result in the standards currently under preparation on this subject.
4) Effect of microwave oven interferences to the performance of digital radio communication systems - S. Miyamoto and N. Morinaga
The paper presented results complementary to the previous one on degradation of the BER due to the emission of microwave ovens for the PHS system operating at 1.9 GHz. The emphasis was on the influence of the power supply type of the microwave oven : ovens with a switching power supply are shown to be significantly more disturbing than ovens with a conventional type.
Questions on possible similar experiments for other radio systems were asked, to which it was answered that some studies on RLANs (Radio Local Area Networks), that are operating inside the ISM band (2.45 GHz) have already started.
5) New techniques for EMC testing of spread spectrum mobile receivers - S. Sali
The paper was presented by R. Singh. It proposes new measurement techniques for different radio parameters to be measured on spread spectrum systems, as a replacement for the test currently defined in the military standards. The suitability of three test set-ups for desensitisation, intermodulation and cross-modulation is theoretically demonstrated, practical experiments are currently starting and will be reported later.
M. Singh being not a full expert of the field, he told us that any questions be directly sent to Dr Sali.
6) Experimental evaluation of RF immunity test facilities for telecommunication equipment above 1 GHz - K. Tajima, N. Kuwabara and M. Tokuda
The paper presented a study conducted in Japan to study the suitability of two different test sites for immunity measurements between 1 and 3 GHz : a fully anechoic room and a GTEM-cell. Presented results show that the field uniformity criteria of the IEC 1000-4-3 extended above 1 GHz is met by the fully anechoic room and not by the GTEM-cell. The correlation between both methods is also presented for the test of an analogue telephone, and is not so good, due to the field non-uniformity of the GTEM-cell.
Questions were asked on the possible deviation of the anechoic room above 2.5 GHz (presented results show that it's not the case) and the actions that will be taken to improve the uniformity of the GTEM-cell (further experiments are on-going).
7) Inference of practical 3-D EM field and multipath interference environments based on dual-frequency microwave holography method - H. Kitayoshi
The paper presents a new method based on holography enabling one to visualize the electromagnetic field strength in three dimensions, that can be used to illustrate the different field rays in a multi-path environments. The principles of the method are explained and examples of indoor propagation at 19 GHz are shown using this technique.
Questions and discussions followed on some details of the principle and the possible frequency range of this method (theoretically, it is valid for all frequencies).
8) Conclusion and future actions
The homogeneity of the session was good and its main interest was to study the link between theoretical and experimental research work on the one hand and the standardization activities in this field on the other hand.
Dr. Kobayashi and myself are of the opinion that it would be interesting to organize a similar session at the next General Assembly as the use of digital systems above 1 GHz, that have recently started and will develop much more in three years.
HEG EM Coupling between the Ground (Including Seismic Activity) and
The Upper Ionosphere and Magnetosphere
reported by M.Parrot
A joint session on this topic was held in the morning of September 5, 1996. About 50 people attended and 11 oral contributions were presented (1 scheduled paper was cancelled). Most of the Russian papers that were submitted were placed in the poster session. Of the 14 papers that were accepted for that session, only 7 posters were actually presented. The discrepancy between the number of papers submitted by Russian authors and the number actually submitted is a problem that detracts from the quality of the sessions.
There were several presentations involving electromagnetic effects observed in relation to the Kobe earthquake in Japan. Presentations were also made on theoretical models to explain the electrical coupling mechanism between the Earth's crust, the surface, and the ionosphere during perturbed seismic conditions. Many examples of electron density perturbations in the ionosphere were discussed in the invited paper. Finally, the importance of man-made waves such as Power Line Harmonics for electron precipitation was described. There were many questions during the oral session and it was clearly a success.
Commission H: M. Parrot (France), O.A. Molchanov (Russia) Commission E: T. Yoshino (Japan)
Commission G: A.C. Fraser-Smith (USA)
JCE: Interference Problems in Radio Astronomy and Communication, or Cosmic ecology
reported by L. W. Barclay
This session took place in the final meeting slot of the Assembly and was crowded, in that one more paper than had been planned was included in the announced time. In fact this gave no problems and all papers were well and clearly presented in the time available. The audience numbered just over 50, and the session seemed to be well appreciated. I anticipate that this topic will continue to be of concern, so that a similar session at a future General Assembly is likely to be of interest.
The increasing exploitation of the radio frequency spectrum for radiocommunications of all types, but particularly by satellite communications systems with a rather wide interference potential, is of considerable concern to radio scientists and especially to radio astronomy are protected from other frequency assignments, the proximity of emissions in adjacent bands can cause considerable problems due to out of band emissions. Such emissions may well meet the normal specifications for radio communications and planning purposes but yet may be unacceptable for radio astronomy.
This session provided the opportunity to explore the problems and some solutions in this topic area.
The international regulatory context was provided by H. Kimball, Chairman of the ITUR Study Group 7: Science Services, in his paper on "the ITU and the science services". This described the way in which studies and recommendations are prepared in SG7. A realistic view of the possibilities for sensitive radio astronomy was given, emphasising the need to work with the regulators to find a satisfactory compromise.
This was followed by a paper on "Ecological responsibility and the ether protecting the future radio environment" by D. M. Boscovic et al. which discussed the basic philosophy of the constraints on spectrum use in the context of modern mobile radio systems.
The paper by W. A. Baan, Chairman of IUCAF, on "Cleaning the windows on our universe" looked at the regulatory situation from the radioscientist's viewpoint and demonstrated the effective way in which IUCAF operates. There are many lessons to be learned, and the author emphasized that there will be a set of new problems to be faced as millimetric wavelengths become more intensively used.
H. C. Kahlmann described "European efforts to maintain some quiet radio sky" in particular the development of ESF-CRAF and its relationship to CEPT and NATO.
The interference environment in the HF range is particularly difficult. Methods for wide bandwidth measurements in this frequency band were described by P. Kleewein et al. in "Digital techniques for ground based, low frequency radioastronomy".
P. Delogne presented "interference of LEO satellites in radio astronomy bands; a case study" which was a valuable illustration of the
desirability of a proper evaluation of modulation methods and their interference potential and showed that by a proper choice of modulation and spectral shaping much to the problem of out band emissions may be avoided.
G. Swarup described an "RF1 survey at the giant metrewave radio telescope site in India". This contrasted with the environment in Europe and showed how the potential of this major and important instrument is being protected by interference reduction and monitoring measures.
"The future of radio astronomical research on the OH radical" was discussed by R. J. Cohen. These frequencies are mentioned in the radio regulations but the interference contamination is growing. The negotiations undertaken with respect to the GLONASS navigation system were described, but the author went on to discuss the difficult problems now posed by the IRIDIUM satellite mobile system which seem likely to substantially restrict the possibility for research in this band.
"Millimetre-wave astronomy - prospects and threats" were considered by A. Winnberg. There are major possibilities for radio astronomy in this part of the spectrum, particularly in cosmological studies, but the need to upgrade the protection and the secure exclusive frequency allocations was emphasized.
Finally T. A. Th. Spoelstra discussed "EMI: a problem = a challenge" and considered this as a dynamic climatological problem with both technical and a political solutions.
Five papers were also presented as Posters; these were:
The arrangement for the poster session at a different time and place from the oral session was unfortunately not very effective.
Masashi Hayakawa
Commission E chairman
Department of Electronic Engineering
The University of Electro-Communications
Chofu Tokyo 182, Japan