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.

Ku band linear slot-array in ridge gapwaveguide technology

Abstract: A Ku band 4×1 linear slot array antenna design based on recently developed gap waveguide technology is presented. The complete antenna has been built using two parallel plates where the bottom metal plate has the guiding ridge and periodic pins and the top metal plate is smooth. The antenna feed network consists of power dividers has been realized on the bottom metal plate, and the radiating slots are placed on the top metal plate. Design and simulation results of the linear array show that it is possible to have a slot array antenna with 20 % bandwidth based on ridge gap waveguide technology.

Optimization of antenna diversity gain by combining full-wave and circuit simulations

Abstract: This paper presents a method for using data from full-wave EM simulations in combination with lumped circuit models for calculating antenna parameters such as radiation patterns, radiation efficiency, diversity gain etc. The method can be applied on multi-port antennas for arbitrary loading and excitation conditions. The paper also describes how the method is used in combination with a global optimization scheme to maximize the diversity gain for a given antenna and circuit layout. The goal function is maximized by optimizing the component values of the given circuit layout. Results for two parallel dipoles and a prototype mobile terminal, both cases with and without the optimized impedance network, are presented. (5 pages)

A small dipole-fed resonant reflector antenna with high efficiency, low cross polarization, and low sidelobes

Abstract: The computer-aided optimization of a small five-wavelength diameter reflector antenna with a center-supported dipole-disk feed is described. The primary radiation is controlled by using a patented beamforming ring to give low cross polarization and low sidelobes due to spillover. The efficiency is maximized by controlling and taking advantage of the multiple reflections between the feed and the reflector. This has inspired the name "resonant reflector antenna." The gain from the feed reflector resonances is so large that it compensates almost completely for the about 1 dB loss due to center blockage of the aperture.

FDTD design of a Chinese hat feed for shallow mm-wave reflector antennas

Abstract: Rotationally symmetric reflectors with hat feeds are attractive for radio link applications the mm-wave band due to their low sidelobes, simple rotationally symmetric structure and low manufacture cost. The standard hat feed has its best performance in a very deep reflector. In this paper, the V2D computer code based on the finite-difference time-domain (FDTD) method is applied to the analysis of a Chinese hat feed, which is optimized for use in a more shallow reflector. The FDTD results have been post processed to obtain the different subefficiencies characterizing spillover, polarization, illumination and phase losses.

Study of element patterns and excitations of the line feeds of the spherical reflector antenna in Arecibo

Abstract: The element patterns of the circularly polarized line feeds for the spherical reflector in Arecibo are calculated, showing strong endfire radiation. The radiation fields of the line feeds are then obtained by adding up the contributions from all elements. The optimum excitation of the feed is found by an approximate stationary-phase solution of the radiation field. This shows that the element pattern gives a large phase contribution to the excitation, because of the finite diameter of the feed. If not corrected for, this phase error can cause losses up to 1.5 dB. The excitation is optimized further by cutting and trying. The validity of the analytical models is checked by calculation of the radiation pattern of the existing 96.6 ft 430 MHz feed. The excitation is modeled from measured phases along the feed. The calculated radiation patterns show good agreement with the measurements, including the phase errors and the dip in the center. By using the proposed new excitation it should be possible to increase the efficiency of the 96.6 ft feed by 0.7 dB and to increase the efficiency of the 40 ft feeds at higher frequencies by even more.

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.