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.

Relations between radiation characteristics of small antennas located in free space and close to lossy phantom

Abstract: The characterization of small terminal antennas close to head phantoms and other lossy objects is time-consuming, and in particular if the radiation patterns are to be measured for many positions close to the phantom. The main effect of a lossy object is absorption and a corresponding reduction in the radiation efficiency of the antenna. For operation in multipath environments with Rayleigh fading the radiation efficiency is the most significant performance parameter; the radiation pattern plays a minor role. Therefore, characterization could be based on only the radiation efficiency, which can be measured fast and accurately in e.g. a reverberation chamber. It has been proposed (and is also practiced some places) to determine the absorption in the head phantom and the corresponding radiation efficiency by simply using the free space radiation pattern to calculate the relative power shadowed by the phantom. The purpose of the present work is to investigate the relevance and accuracy of such an approach, compared to an actual measurement of radiation efficiency

The gap waveguide as a metamaterial-based electromagnetic packaging technology enabling integration of MMICs and antennas up to THz

Abstract: This paper presents new topics that will be lectured in the short course Metamaterials for Antennas within the European School of Antennas in Spring 2012. These relates to new so-called gap waveguides that are advantageous for use above 30 GHz, because they are quasi-TEM over wide bandwidth, and do neither require dielectric material nor conductive joints between metal parts. The gap waveguides originate from research on soft and hard surfaces that also are forerunners for EBG surfaces (acting as isotropic soft surfaces) and metamaterial cloaks (realized first by hard surfaces). The course will contain material related to all these topics, and in addition an overview of the last years research on the gap waveguides including experimental demonstration of principles as well as working hardware components. In this presentation special emphasis will be given to electromagnetic (EM) packaging, the principle of PMC packaging and integration of MMICs.

An Improved MM-PO Method with UV Technique for Scattering from an Electrically Large Ship on a Rough Sea Surface at Low Grazing Angle

Abstract: ─ An improved MM-PO-UV hybrid method is developed to calculate the bistatic scattering from the two-dimensional (2-D) composite model of an electrically large ship (ELS) on a one-dimensional (1-D) rough sea surface at a low grazing angle (LGA). The subdivision of the MM and PO region is performed flexibly according to the physical considerations. The MM region contains not only the ship but also a small portion of the neighboring sea region where the surface currents need to be modeled accurately. An iterative solution BiCGSTAB is adopted to solve the final matrix equation of a large dimension caused by the ELS. Then, a UV matrix decomposition technique is applied as the fast algorithm to accelerate the matrix-vector productions and the matrix elements filling in. The improved method makes it possible for the Monte-Carlo simulation of large-scale complex target/rough surface problems under an LGA. The accuracy is validated in comparison with the traditional MOM method. Index Terms ─ LGA, MM-PO hybrid method, target/rough surface scattering, UV.

Performance of different theoretical small antennas in isotropic 3-D and horizontal 2-D multipath environments with application to OTA testing

Abstract: There is a need for new measurement methods that can emulate multipath environments for Over-The-Air (OTA) testing of devices with small antennas and in particular when the communication system can generate dynamically changing multiple channels through the multipath by means of multiport antennas, i.e. having MIMO capability (Multiple Input Multiple Output). The reverberation chamber has during the last ten years been developed into an accurate method for such testing [1], representing an isotropic three-dimensional (3-D) environment with a uniform distribution of incoming waves over the unit sphere. Lately it has been proposed to instead perform such tests in a horizontal two-dimensional (2-D) environment realized by antennas located in a ring around the DUT. This paper will present a comparison of theoretical results of simulating such tests in rich isotropic 3-D and horizontal 2-D environments. The results are presented in terms of Mean Effective Gains (MEG) [2] or rather Mean Effective Directivities (MED) [1], and apparent diversity gains [3], obtained by using a multipath simulator based on the receive antenna equivalent circuit in [4] and the theory in [5].

Measurements of Radiated Power and Radiated Receiver Sensitivity in Reverberation Chambers

Abstract: Chalmers and Bluetest AB have the last years shown that it is possible to measure radiated power and total isotropic receiver sensitivity in the statistic field environment created by a reverberation chamber. The new measurement method has been developed for mobile and wireless terminals such as mobile phones. However, the approach is also valid for measurements at higher frequencies, and e.g. to measure the performance of integrated antennas not being separable from their transmit or receive amplifiers. The purpose of the present paper is to describe measurements of radiated power and receive sensitivity in reverberation chambers of mobile terminals, and to show that this also can be done at higher frequencies. The measurement accuracy and how this depends on frequency will be explained.

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.