Per-Simon Kildal

Bio: Per-Simon Kildal is an academic researcher from Chalmers University of Technology. The author has contributed to research in topics: Antenna (radio) & Electromagnetic reverberation chamber. The author has an hindex of 60, co-authored 504 publications receiving 13470 citations. Previous affiliations of Per-Simon Kildal include SP Technical Research Institute of Sweden & Norwegian Institute of Technology.

Development of reverberation chamber for accurate measurements of mobile phones and mobile phone antennas

Abstract: Reverberation chambers have been used for quite some time for EMC measurements. Some early work was also done in antenna measurements, but the achieved accuracy was not sufficient for the method to be accepted. The paper describes the development of a reverberation chamber for antenna measurements and the applications for which it can be used. The disadvantage of using a reverberation chamber for measurement of small antennas and wireless terminals is that it is not possible to generate radiation diagrams. In some cases these are needed to fulfil specifications or by customers used to seeing the diagram as the only way of specifying their products. We know that some would like to use MEG to specify radiation, and this is not easily achieved in a totally uniform multipath environment. On the other hand we have met a growing understanding that this method is suitable for most of the measurements that have to be done throughout the development and evaluation of small wireless terminals: measurement of antenna characteristics (passive unit or cable fed terminal); total radiated power; head loss and prequalification of SAR values; receive sensitivity; spurious radiation.

Performance of Directive Multi-element Antennas versus Multi-beam Arrays in MIMO Communication Systems

Abstract: Performance of Directive Multi-element Antennas versus Multi-beam Arrays in MIMO Communication Systems

Reduction of second-order beams in slotted waveguide arrays using baffles

Abstract: In waveguide fed slot arrays, the periodicity of the slots cause unwanted grating lobes off the principal planes referred to as second-order beams. These lobes can be reduced by using baffles. The authors present an efficient method to calculate the radiation pattern of longitudinal slot arrays with baffles by reducing the three dimensional field problem to a two dimensional one via a Fourier-z transform.

Analysis of statistical uncertainties involved in estimating ergodic MIMO capacity and diversity gain in Rayleigh fading environment

Abstract: Statistical uncertainties involved in the evaluation of ergodic MIMO capacity and diversity gain in a fading environment is investigated. The study is based on results from a numerical simulation tool called “Rayleigh-Lab.” This tool can be used for accuracy investigation of MIMO capacity and diversity gain, and to determine the number of independent samples needed to estimate them with a reasonable level of confidence. The MIMO capacity is evaluated using Shannon's channel capacity formula. Two different methods of evaluating diversity gains are compared: based on CDF curves, and based on estimating correlation and radiation efficiency and then using them in a newly available compact formula for calculating the diversity gain. Rayleigh-Lab emulates Rayleigh channels by generating sequences of random complex numbers and it provides a convenient graphical user-interface for a pedagogical study of average power level (proportional to antenna efficiency), correlation, diversity gain and maximum available capacity.

High-impedance electromagnetic surfaces with a forbidden frequency band

Abstract: A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.

Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy

Abstract: Herschel was launched on 14 May 2009, and is now an operational ESA space observatory o ering unprecedented observational capabilities in the far-infrared and submillimetre spectral range 55 671 m. Herschel carries a 3.5 metre diameter passively cooled Cassegrain telescope, which is the largest of its kind and utilises a novel silicon carbide technology. The science payload comprises three instruments: two direct detection cameras/medium resolution spectrometers, PACS and SPIRE, and a very high-resolution heterodyne spectrometer, HIFI, whose focal plane units are housed inside a superfluid helium cryostat. Herschel is an observatory facility operated in partnership among ESA, the instrument consortia, and NASA. The mission lifetime is determined by the cryostat hold time. Nominally approximately 20,000 hours will be available for astronomy, 32% is guaranteed time and the remainder is open to the worldwide general astronomical community through a standard competitive proposal procedure.

Photonic crystals

Abstract: The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

Transformation optics and metamaterials

Abstract: Transformation optics describes the capability to design the path of light waves almost at will through the use of metamaterials that control effective materials properties on a subwavelength scale. In this review, the physics and applications of transformation optics are discussed.

The 2017 terahertz science and technology roadmap

Abstract: Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies.