ALBERT

Description: Measurement and evaluation of radar cross section for furniture in an indoor propagation channel Advances in Radio Science, 12, 273-278, 2014 Author(s): M. M. Maw, P. Supanakoon, S. Promwong, and J. Takada This paper has attempted to evaluate the radar cross section (RCS) of two furniture items in an indoor environment in a frequency range of 3–7 GHz of the ultra-wideband (UWB) range. The RCS evaluation is achieved through an extended version of the radar equation that incorporates the channel transfer function of scattering. The time-gating method was applied to remove the multipath effect, a phenomenon which typically occurs in the indoor environment. Two double-ridged waveguide horn antennas for both vertical and horizontal polarizations were used to obtain the transfer function of scattering of the furniture prior to analysis in order to derive their bistatic RCS. The RCS results validate the applicability of the proposed extended radar equation to the indoor propagation prediction.

Description: An extended mode-matching model for improved relative permittivity measurements using a split-cylinder resonator Advances in Radio Science, 12, 267-272, 2014 Author(s): S. Zinal and U. Arz In this paper we present an extended mode-matching model for a split-cylinder resonator involving TE and TM resonant modes. The new model enhances the known TE 0np mode-matching model by improving mode identification and distortion analysis and providing better frequency range coverage for relative permittivity estimation. In order to verify the new model, measured spectra of several substrate materials are analyzed and the estimation results are compared with those of the TE 0np mode-matching model.

Description: Ionospheric research in Germany prior to Karl Rawer Advances in Radio Science, 12, 225-230, 2014 Author(s): K. Schlegel This brief historical review summarizes the work and achievements of German researchers on ionospheric problems before Karl Rawer started his scientific career in 1937.

Description: Planetary radio astronomy: Earth, giant planets, and beyond Advances in Radio Science, 12, 211-220, 2014 Author(s): H. O. Rucker, M. Panchenko, and C. Weber The magnetospheric phenomenon of non-thermal radio emission is known since the serendipitous discovery of Jupiter as radio planet in 1955, opening the new field of "Planetary Radio Astronomy". Continuous ground-based observations and, in particular, space-borne measurements have meanwhile produced a comprehensive picture of a fascinating research area. Space missions as the Voyagers to the Giant Planets, specifically Voyager 2 further to Uranus and Neptune, Galileo orbiting Jupiter, and now Cassini in orbit around Saturn since July 2004, provide a huge amount of radio data, well embedded in other experiments monitoring space plasmas and magnetic fields. The present paper as a condensation of a presentation at the Kleinheubacher Tagung 2013 in honour of the 100th anniversary of Prof. Karl Rawer, provides an introduction into the generation mechanism of non-thermal planetary radio waves and highlights some new features of planetary radio emission detected in the recent past. As one of the most sophisticated spacecraft, Cassini, now in space for more than 16 years and still in excellent health, enabled for the first time a seasonal overview of the magnetospheric variations and their implications for the generation of radio emission. Presently most puzzling is the seasonally variable rotational modulation of Saturn kilometric radio emission (SKR) as seen by Cassini, compared with early Voyager observations. The cyclotron maser instability is the fundamental mechanism under which generation and sufficient amplification of non-thermal radio emission is most likely. Considering these physical processes, further theoretical investigations have been started to investigate the conditions and possibilities of non-thermal radio emission from exoplanets, from potential radio planets in extrasolar systems.

Description: Probability of occurrence of planetary ionosphere storms associated with the magnetosphere disturbance storm time events Advances in Radio Science, 12, 261-266, 2014 Author(s): T. L. Gulyaeva, F. Arikan, and I. Stanislawska The ionospheric W index allows to distinguish state of the ionosphere and plasmasphere from quiet conditions ( W = 0 or ±1) to intense storm ( W = ±4) ranging the plasma density enhancements (positive phase) or plasma density depletions (negative phase) regarding the quiet ionosphere. The global W index maps are produced for a period 1999–2014 from Global Ionospheric Maps of Total Electron Content, GIM-TEC, designed by Jet Propulson Laboratory, converted from geographic frame (−87.5:2.5:87.5° in latitude, −180:5:180° in longitude) to geomagnetic frame (−85:5:85° in magnetic latitude, −180:5:180° in magnetic longitude). The probability of occurrence of planetary ionosphere storm during the magnetic disturbance storm time, Dst, event is evaluated with the superposed epoch analysis for 77 intense storms (Dst ≤ −100 nT) and 230 moderate storms (−100 〈 Dst ≤ −50 nT) with start time, t 0 , defined at Dst storm main phase onset. It is found that the intensity of negative storm, iW - , exceeds the intensity of positive storm, iW + , by 1.5–2 times. An empirical formula of iW + and iW - in terms of peak Dst is deduced exhibiting an opposite trends of relation of intensity of ionosphere-plasmasphere storm with regard to intensity of Dst storm.

Description: Extreme ultraviolet (EUV) solar spectral irradiance (SSI) for ionospheric application – history and contemporary state-of-art Advances in Radio Science, 12, 251-260, 2014 Author(s): G. Schmidtke, Ch. Jacobi, B. Nikutowski, and Ch. Erhardt After a historical survey of space related EUV measurements in Germany and the role of Karl Rawer in pursuing this work, we describe present developments in EUV spectroscopy and provide a brief outlook on future activities. The group of Karl Rawer has performed the first scientific space project in Western Europe on 19th October 1954. Then it was decided to include the field of solar EUV spectroscopy in ionospheric investigations. Starting in 1957 an intensified development of instrumentation was going on to explore solar EUV radiation, atmospheric airglow and auroral emissions until the institute had to stop space activities in the early nineteen-eighties. EUV spectroscopy was continued outside of the institute during eight years. This area of work was supported again by the institute developing the Auto-Calibrating Spectrometers (SolACES) for a mission on the International Space Station (ISS). After more than six years in space the instrument is still in operation. Meanwhile the work on the primary task also to validate EUV data available from other space missions has made good progress. The first results of validating those data and combine them into one set of EUV solar spectral irradiance are very promising. It will be recommended for using it by the science and application community. Moreover, a new low-cost type of an EUV spectrometer is presented for monitoring the solar EUV radiation. It shall be further developed for providing EUV-TEC data to be applied in ionospheric models replacing the Covington index F 10.7 . Applying these data for example in the GNSS signal evaluation a more accurate determination of GNSS receiver positions is expected for correcting the propagation delays of navigation signals traveling through the ionosphere from space to earth. – Latest results in the field of solar EUV spectroscopy are discussed, too.

Description: Kleinheubach-U.R.S.I.: 48~years home for the German-Austrian Beacon Satellite Community (BSC) Advances in Radio Science, 12, 237-239, 2014 Author(s): G. K. Hartmann No abstract available.

Description: Remote sensing and modeling of lightning caused long recovery events within the lower ionosphere using VLF/LF radio wave propagation Advances in Radio Science, 12, 241-250, 2014 Author(s): E. D. Schmitter On the 4 November 2012 at 3:04:27 UT a strong lightning in the midst of the North Sea affected the propagation conditions of VLF/LF transmitter radio signals from NRK (Iceland, 37.5 kHz) and GBZ (UK, 19.58 kHz) received at 5246° N 8° E (NW Germany). The amplitude and phase dips show a recovery time of 6–12 min pointing to a LOng Recovery Early VLF (LORE) event. Clear assignment of the causative return stroke in space and time was possible with data from the WWLLN (Worldwide Lightning Location Network). Based on a return stroke current model the electric field is calculated and an excess electron density distribution which decays over time in the lower ionosphere is derived. Ionization, attachment and recombination processes are modeled in detail. Entering the electron density distribution in VLF/LF radio wave propagation calculations using the LWPC (Long Wavelength Propagation Capability) code allows to model the VLF/LF amplitude and phase behavior by adjusting the return stroke current moment. The results endorse and quantify the conception of lower ionosphere EMP heating by strong – but not necessarily extremely strong – return strokes of both polarities.

Description: Karl Rawer: space research and international cooperation – Laudation on the occasion of the 100 th birthday of Professor Karl Rawer Advances in Radio Science, 12, 221-223, 2014 Author(s): B. W. Reinisch This laudation is given in honor of the 100 th birthday of Prof. Karl Rawer which happens to coincide with the 45th anniversary of the International Reference Ionosphere (IRI). The ionosphere was discovered during Karl Rawer's lifetime, and he has dedicated his professional life to its exploration. World Wars I and II shaped his early life, but they also launched his career as one of the eminent geophysical scientists of the twentieth century. The paper looks back at Karl Rawer's life and his pioneering work and leadership in advancing and shaping the exploration of the ionosphere.

Description: The International Reference Ionosphere: Rawer's IRI and its status today Advances in Radio Science, 12, 231-236, 2014 Author(s): D. Bilitza When the Committee on Space Research (COSPAR) initiated the International Reference Ionosphere (IRI) project in 1968 it wisely selected K. Rawer as its first Chairperson. With a solid footing and good contacts in both the ground-based and space-based ionospheric communities he was ideally suited to pull together colleagues and data from both communities to help build the first version of the IRI. He assembled a team of 20+ international ionospheric experts in the IRI Working Group and chaired and directed the group from 1968 to 1984. The working group has now grown to 63 members and the IRI model has undergone many revisions as new data became available and new modeling techniques were applied. This paper was presented during a special session of the Kleinheubach Tagung 2013 in honor of K. Rawer's 100th birthday. It will review the current status of the IRI model and project and the international recognition it has achieved. It is quite fitting that this year we not only celebrate K. Rawer's 100th birthday but also the exciting news that his favorite science endeavor, IRI, has been internationally recognized as an ISO (International Standardization Organization) standard. The IRI homepage is at http://irimodel.org .