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

We show how Total Isotropic Sensitivity (TIS) of 4G Long Term Evolution (LTE) devices can be estimated from over-the-air (OTA) throughput measurements in reverberation chamber. The proposed approach is more time efficient than the standard TIS measurement method. The relative throughput itself represents Probability of Detection (PoD), and it shows clearly the quality of the Multiple-Input Multiple-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) implementation in the receiver terminal. This makes the throughput a complete metric of the receiver quality.

Estimating TIS of 4G LTE devices from OTA throughput measurements in reverberation chamber

Modeling of gap-waveguide structures with single and multiple transmission lines is performed using spectral domain Green's functions approach. The approach is extended using even/odd mode analysis in order to also estimate the crosstalk levels between neighboring transmission lines. The results of this analysis are compared with the results of a commercial electromagnetic solver and with the measured results.

http://publications.lib.chalmers.se/records/fulltext/156677/local_156677.pdf

Analytical modeling and experimental verification of coupling between transmission lines in gap-waveguides

Effective diversity gain of two parallel dipoles: theory and measurement in reverberation chamber

In this paper, we demonstrate the effects of mutual coupling on embedded radiation efficiency, correlation, diversity gain, and MIMO efficiency for single and multiple bit streams in rich isotropic multipath (RIMP) environment by using parallel dipoles and a compact wideband four-port antenna as examples.

The simple truth about effects of mutual coupling in MIMO arrays for single and multiple bit streams in rich isotropic multipath

본 발명은 적어도 의도된 동작 주파수 대역에서, 원하는 방향 또는 도파로 경로에서 도파로 개구(3) 주위의 표면 사이의 간극을 가로질러 파동이 다른 도파로 개구로 통과하게 하고, 다른 방향에서 간극 내의 파동의 전파를 저지하도록 배열되거나 설계된 다수의 돌출 요소(115)에 의해 형성된 주기적 또는 의사-주기적 구조체(15)를 갖는 전도성 재료의 표면을 포함하는 다수의 도파로 플랜지 어댑터 요소(100)를 포함하는 도파로 구조체(10, 20) 또는 구성요소의 상호연결을 위한 장치(100)에 관한 것이다. 이 장치는 전기적 또는 전도성 접촉을 요구하지 않고 도파로 플랜지 또는 다른 도파로 플랜지 어댑터 요소와 상호연결을 허용하고 주기적으로 또는 의사-주기적으로 배열된 돌출 요소(115)에 의해 형성된 적어도 하나의 표면(15)과 다른 도파로 플랜지(20)의 또는 도파로 개구 주위의 표면 사이에 간극이 존재하는 것을 보장하고, 따라서 주기적으로 또는 의사-주기적으로 배열된 돌출 요소(115)에 의해 형성된 표면(15)이 다른 대향하는 상호연결 도파로 플랜지(20)와 직접 기계적으로 접촉하지 않는 것을 보장하는 수단을 포함한다.

Per-Simon Kildal

Papers

Estimating TIS of 4G LTE devices from OTA throughput measurements in reverberation chamber

Analytical modeling and experimental verification of coupling between transmission lines in gap-waveguides

Effective diversity gain of two parallel dipoles: theory and measurement in reverberation chamber

The simple truth about effects of mutual coupling in MIMO arrays for single and multiple bit streams in rich isotropic multipath

도파로 구조체들의 상호연결을 위한 장치 및 도파로 구조체 상호연결용 장치를 위한 구조체