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.

Analysis of arrays of rectangular waveguides radiating through stepwise transitions with dielectrically loaded hard walls in one plane

Abstract: Planar antenna arrays of rectangular waveguides radiating through step transitions whose walls are loaded in one plane with a dielectric so that the hard-wall boundary condition is satisfied are considered. The analysis uses the multimode scattering matrix method. It is shown that finite waveguide sections with hard walls are capable of removing the blindness effects inherent in arrays of waveguides with a small cross section and homogeneous filling; the matching of the array remains sufficiently good. Characteristics of H-plane sectoral-horn and pyramidal-horn arrays are also calculated. The sectoral horns with hard walls are found to operate in a wider frequency band than similar sectoral box horns. The efficiency of hard-wall pyramidal-horn arrays is 2 dB higher than that of arrays of similar square box horns.

Correlation between far-field patterns on both sides of the head of two-port antenna on mobile terminal

Abstract: We present an electromagnetic simulation of a practical mobile terminal with a two-port MIMO antenna on left and right sides of the head. The computed far-field patterns include the effect of head and hand phantoms. We show that the far-field patterns on the two sides are strongly correlated if they are presented in the coordinate system of the phone, but they are completely uncorrelated in the coordinate system of the environment.

Micromachined ridge gap waveguide for sub millimeter and millimeter wave applications

Abstract: High-frequency waveguide technology has become a field of great interest lately. In this paper we present a ridge gap waveguide with two 90 degree bends and a ridge gap waveguide resonator, both fabricated with MEMS technology. It is the first time the ridge gap waveguides have been fabricated for millimeter waves. The ridge gap waveguides is realized of two conducting plates, one of them with a texture, and can provide low transmission losses without any requirements to alignment between the two plates, and with neither conductive joints nor sidewalls. The Ridge gap waveguide makes use of a ”bed of nails” structure which acts as a magnetic conductor and creates a cut-off for parallel plate modes between the two plates. Thereby, wave propagation is confined to the electric conducting ridge, without making use of electrically conducting sidewalls. MEMS technology can provide precision machining which makes it possible to go up in higher frequency bands than with conventional machining. The purpose of this paper is to describe the the fabrication process of the surface textured with pins and ridge.

A planar multilayer antenna

Abstract: A planar antenna (170) is presented, which includes a radiation Printed Circuit Board (PCB) layer (310) including at least one array of at least two radiating elements, said radiation PCB layer being arranged for radiation of signals to be transmitted by said antenna. The antenna further includes a power distribution PCB layer (330) in parallel with said radiation PCB layer, arranged for providing each one of said at least two radiating elements with power needed for said radiation of said signals. The antenna further includes a spacing layer (320) arranged between said radiation PCB layer and said power distribution PCB layer, and including at least one spacer (321). Hereby, an air gap adjoining said power distribution PCB layer and having an equal thickness Tspacer over said air gap is created, whereby at least one gap waveguide is provided in said air gap.

Experimental and theoretical study of OTA throughput of 4G LTE wireless terminals for different system bandwidths and coherence bandwidths in Rich Isotropic Multipath

Abstract: The 3rd Generation Partnership Project (3GPP) has provided successful reports and specifications for Long Term Evolution (LTE). The LTE standard is the latest communication technology standard today which is extensively adopted by the industry to satisfy the demands of their customers with high speed internet and low latency. The major differences between LTE and its predecessor telecommunication standards i.e. WCDMA and GSM are Orthogonal Frequency Division Multiplexing (OFDM), Multiple-Input Multiple-Output (MIMO), and scalable bandwidth which provide improved receiver sensitivity, higher throughput data-rates, and flexibility. The purpose of the present paper is to study measured throughput for different system bandwidths and see how well the OFDM model works for all these, and to investigate how the threshold level change with the system bandwidth.

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.