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.

To IEEE Antennas and Propagation Society Members [President’s Message]

Abstract: It is my deep honor and pleasure to serve as the 2023 president of the IEEE Antennas and Propagation Society (AP-S). During the first few months of the year, several important discussions and decisions have been taken by the Society. What we can do to serve our members was a primary topic of discussion at the AdCom meeting held in Dubai on 25 February 2023. The proposal by Branislav Notaros, president-elect, and myself to lower the registration fee for student members of AP-S to US$1 has been approved by the AdCom. This will allow our Society to attract many more student members in the near future. The balance of the Society for 2022 is extremely positive with a surplus mainly due to publications, paper downloading, and conference revenues. In 2022, we have had significant investments in new initiatives, mainly addressed to students and early-stage researchers, like the AP-S Fellowship (48 students awarded), Student Travel Grants (34 students awarded), and Undergraduate Summer Research Scholarship (20 students awarded). These initiatives are in addition to the several already existing successful programs to support students, including the C.J. Reddy Travel Grant.

Anomaly when studying electromagnetic radiation from the open end of ideally hard circularwaveguide

Abstract: The problem of electromagnetic radiation from an open-ended circular waveguide exited in the dominant TEM mode is considered. The TEM mode is supported by the ideal zero thickness hard wall of a pipe perfectly conducting the electric and magnetic currents in the longitudinal direction. By using the Weinstein method, the problem is reduced to the functional equations corresponding to the hard acoustic waveguide excited in the fundamental axially symmetrical mode. The rigorous solution shows that the radiation pattern and aperture efficiency are the same as those for the acoustic case, while the field of the reflected TEM mode, unlike that of the incident mode, shows the anomaly of being concentrated at the outer waveguide surface due to the wall anisotropy. Weinstein (3) was developed by Skobelev at. al.(4) and allowed considerable refining the results. In the present paper, we continue studying the hard waveguide, assuming that the open-ended circular waveguide has an ideal hard wall. The term ideal means here that, according to Kildal et. al.(5), the wall has zero thickness, and the pipe itself is a structure perfectly conducting the electric and magnetic currents in the longitudinal direction only. The study includes some features of the TEM mode propagating in the chosen waveguide model, as well as gives the solution for such an open-ended waveguide excited in the TEM mode. SOME FEATURES OF THE IDEAL HARD PIPE The solutions for the modal fields in the ideal hard pipe have been given by Ruvio (6), however, some of their features, to be discussed below, have not been revealed. Consider an infinite pipe of magnetic and electric currents, of radius a, the axis of which coincides with the z axis of the cylindrical system of coordinates ρ, ϕ, and z. Omitting the time dependence e iωt , we specify the current densities in the form

Packaging of active and passive microwave circuits using a grid of planar conducting elements on a grid of vertically arranged substrates

Abstract: The present invention represents a new, way of packaging passive and active microwave circuits, and in particular circuits involving microstrip transmission lines and similar substrate bound transmission lines. The circuits are located between two conducting surfaces, one of these surface may be the ground plane of the microwave circuit, and at least one of these surfaces are provided with conducting elements formed as angular or curved conducting lines arranged on substrates. The conducting lines may e.g. have a zigzag shape. The two surfaces may form the bottom and lid of a cavity with conducting sidewalls. The conducting elements may with advantage be arrange in a periodic grid, and create together with the ground plane of the microwave circuit board or the smooth metal plane below the microwave circuit board a stop band for waves propagating between the lid with conducting elements and the ground plane. Thereby, cavity resonances are avoided or suppressed that otherwise create a big problem associated with the packaging in metal boxes with smooth metal walls.

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.