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.

Wide-Band Slot Antenna Arrays With Single-Layer Corporate-Feed Network in Ridge Gap Waveguide Technology

Abstract: Single-layer, wideband, and low-loss corporate-feed networks for slot antenna arrays are described. The antenna is built using ridge gap waveguide technology, formed between two parallel metal plates without the requirements of electrical contact between these plates. The corporate-feed network is realized by a texture of pins and a guiding ridge in the bottom plate, and the radiating slots are placed in the smooth top plate. The paper describes two test antennas: a 4 $\,\times\,$ 1 linear slot array and a 2 $\,\times\,$ 2 planar slot array. Both have been fabricated and tested at Ku- band. The linear array shows more than 20% bandwidth and the 2 $\,\times\,$ 2 array shows a bandwidth of 21% for 10-dB return loss. There are good agreements between measured and simulated patterns for both antennas. Measured gain for the planar array is found to be at least 12.2 dBi over 12–15 GHz band.

Design and Fabrication of a High-Gain 60-GHz Corrugated Slot Antenna Array With Ridge Gap Waveguide Distribution Layer

Abstract: A wideband high-gain high-efficiency $16 \times 16$ -element slot antenna array is presented for 60-GHz band applications. The antenna is designed based on gap waveguide technology. The most important advantage of using this technology is its ability to decrease complexity and cost of fabrication because there is no requirement of electrical contact between the three layers of the antenna structure. The three layers are a corrugated metal plate with radiating slots, a subarray cavity layer, and a ridge gap waveguide (RGW) feed network layer. The corporate feed network is realized by a texture of pins and guiding ridges in a metal plate. Also, in order to excite the antenna with a standard V-band rectangular waveguide, a transition from RGW to WR-15 is designed. The radiating elements, corrugations, cavity layer, power dividers, and transition are designed and optimized to suppress the reflection coefficient at the input WR-15 port over the desired frequency range from 57 to 66 GHz. Finally, the $16 \times 16$ -element slot antenna array is fabricated by the standard milling technology. The measured results demonstrate about 16% of reflection coefficient bandwidth ( $\vert S_{11}\vert dB) covering the 56–65.7-GHz frequency range, and the measured gain is larger than 32.5 dBi over the band with more than 70% antenna efficiency.

Corrections to “Channel Sounding of Loaded Reverberation Chamber for Over-the-Air Testing of Wireless Devices—Coherence Bandwidth Versus Average Mode Bandwidth and Delay Spread”

Abstract: This letter finds the relation between different parameters that characterize the reverberation chamber as a channel emulator for over-the-air (OTA) testing of wireless devices and components. It is shown experimentally for the first time that the coherence bandwidth is proportional to the average mode bandwidth of the chamber. Both coherence bandwidth and average mode bandwidth increase when the chamber is loaded with absorbing objects, and thereby, the reverberation chamber can be controlled to emulate many different real-life environments. The relationship between RMS delay spread and coherence bandwidth are found from the measured channel response and are equal to the theoretical relation for isotropic multipath environments, being within previously published fundamental limits.

OTA Testing in Multipath of Antennas and Wireless Devices With MIMO and OFDM

Abstract: New over-the-air (OTA) measurement technology is wanted for quantitative testing of modern wireless devices for use in multipath. We show that the reverberation chamber emulates a rich isotropic multipath (RIMP), making it an extreme reference environment for testing of wireless devices. This thereby complements testing in anechoic chambers representing the opposite extreme reference environment: pure line-of-sight (LOS). Antenna diversity gain was defined for RIMP environments based on improved fading performance. This paper finds this RIMP-diversity gain also valid as a metric of the cumulative improvement of the 1% worst users randomly distributed in the RIMP environment. The paper argues that LOS in modern wireless systems is random due to randomness of the orientations of the users and their devices. This leads to the definition of cumulative LOS-diversity gain of the 1% worst users in random LOS. This is generally not equal to the RIMP-diversity gain. The paper overviews the research on reverberation chambers for testing of wireless devices in RIMP environments. Finally, it presents a simple theory that can accurately model measured throughput for a long-term evolution (LTE) system with orthogonal frequency-division multiplexing (OFDM) and multiple-input-multiple-output (MIMO), the effects of which can clearly be seen and depend on the controllable time delay spread in the chamber.

Electromagnetic analysis of effective and apparent diversity gain of two parallel dipoles

Abstract: Two parallel dipoles are often used as a reference case for measuring diversity gain. The present paper shows how to calculate the radiation efficiency, effective diversity gain, and apparent diversity gain of two parallel dipoles and how they depend on dipole spacing. We treat several cases for different terminations of the neighboring dipole; open-circuited, short-circuited, and 50 /spl Omega/ termination. The results for 50 /spl Omega/ termination are verified by measurements of effective diversity gain in a reverberation chamber.

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.