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.

/pdf/high-impedance-electromagnetic-surfaces-with-a-forbidden-3vtu72a5an.pdf

High-impedance electromagnetic surfaces with a forbidden frequency band

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.

/pdf/herschel-space-observatory-an-esa-facility-for-far-infrared-3pdcouv7zo.pdf

Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy

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.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

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.

Transformation optics and metamaterials

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.

https://iopscience.iop.org/article/10.1088/1361-6463/50/4/043001/pdf

The 2017 terahertz science and technology roadmap

Input impedance and radiation pattern of patch on multilayer cylinder

http://ieeexplore.ieee.org/iel6/8258/25864/01149755.pdf

Efficient computer programs for study and optimization of blockage and diffraction in symmetrical reflector antennas

Inverted microstrip gap waveguide is advantageous for millimeter wave application because of its low-loss, self-packaging characteristics and cost-effectiveness. In this work a planar gap waveguide slot array is presented. It is fed by a corporate distribution network realized in inverted microstrip gap waveguide. The structure consists of three layers. The top layer contains subarrays of 2 × 2 radiating slots. This is backed by an air-filled groove gap waveguide cavity. This cavity layer is fed by the inverted microstrip gap waveguide distribution network formed in the air-gap between the middle and bottom layer. The paper presents a design of the 2 × 2 subarray, i.e. the unit cell using simulations in an infinite array environment. The simulation results show that the S11 is below ™11 dB over 57–66 GHz frequency band covering 14% bandwidth, and the simulated directivity is about 39 dBi when evaluated for a 32 × 32 element slot array antenna.

/pdf/design-of-a-cavity-backed-slot-array-unit-cell-on-inverted-f0r87csjbo.pdf

Design of a cavity-backed slot array unit cell on inverted microstrip gap waveguide

Design of Micromachined Ridge Gap Waveguides for Millimeter-Wave Applications

We present an overview of the recent developments of a cryogenic 2–14 GHz feed system for the Very Long Baseline Interferometry 2010 (VLBL2010) project. The developments include a new balun feeding network, a new circular Eleven feed, system noise temperature modeling and testing, integration with different low noise amplifiers (LNAs), and cryostat design and integration.

https://publications.lib.chalmers.se/records/fulltext/156676/local_156676.pdf

Per-Simon Kildal

Papers

Input impedance and radiation pattern of patch on multilayer cylinder

Efficient computer programs for study and optimization of blockage and diffraction in symmetrical reflector antennas

Design of a cavity-backed slot array unit cell on inverted microstrip gap waveguide

Design of Micromachined Ridge Gap Waveguides for Millimeter-Wave Applications

Development of the cryogenic 2–14 GHz Eleven feed system for VLBI2010