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.

Revisiting the complex correlation in a MIMO system

Abstract: It is commonly believed that a complex correlation of up to 0.5 in magnitude is negligible for multiple-input multiple-output (MIMO) performances and that the correlation affects the diversity gain or throughput only via its magnitude. In this work, we show that when the number of antenna ports is larger than two, the phase of the correlation coefficient affects the diversity gain and that even small correlation can severely degrade the throughput performance of MIMO systems with full spatial multiplexing and no diversity gain. We assume maximum ratio combining (MRC) to investigate the correlation effect on diversity gain and zero-forcing (ZF) equalizer to study the correlation effect on the MIMO throughput.

Packaging of MMIC by using gap waveguide and design of a microstrip to ridge gap waveguide transition

Abstract: In this work, gap waveguide based packaging technique is used to improve the isolation among critical microwave circuit components such as high gain amplifier chain. Amplifier chains at Ka-band were tested for a stable forward gain and it was found that-with gap waveguide packaging, 65~70dB of forward gain is achievable without the problem of self-resonance. Apart from the new packaging technique, a low-loss transition from microstrip to ridge-gap waveguide had been designed and tested. This transition is a key component to connect such amplifier chains to a planar slot array antenna. Experimental results for manufactured back to back transition show 14 dB return loss over 55% relative bandwidth from 2343GHz.

Overview of state-of-the-art OTA measurements of wireless devices in reverberation chamber

Abstract: We present an overview of the state-of-the-art over-the-air (OTA) measurements in reverberation chamber (RC) of wireless devices for the long term evolution (LTE) MIMO system based on our previous work. The measured throughput is well described by a simple and basic theoretical model based on an ideal threshold receiver, under different channel conditions and system configurations. Intuitive explanations to the measurement results are given. The reverberation chamber (RC) is shown to be an effective tool for active OTA tests, which extends its capabilities considerably compared to its original application for EMC tests.

Design of a four-element horn antenna array fed by inverted microstrip gap waveguide

Abstract: The paper presents the design of a four-element slot coupled dual-mode horn array with microstrip gap waveguide as feed network. We present simulated results for return loss for the feed network both with and without the radiating horn array. We also compare results for two ways to generate the stopband of the parallel-plate modes: the ideal Perfect Magnetic Conductor used during the initial design, and the real bed of nails used in the practical realization. The study is performed at 60 GHz obtaining about 10% bandwidth.

Software for Optimizing multi-port antennas based on precomputed embedded element patterns from commerical codes

Abstract: Software for optimizing multi-port antennas based on precomputed embedded element patterns from commerical codes

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.