We propose the concept of ultra-broadband terahertz communication, based on directed non-line-of-sight (NLOS) transmissions. Potential applications of such a system supporting multi-gigabit data rates are given, and put into the context of currently emerging WLANs/WPANs. The technology and propagation constraints serve as boundary conditions for the determination of the required antenna gain to support ultra-broadband communication. Resulting high-gain antenna requirements will necessitate highly directed transmissions. We propose the use of omni-directional dielectric mirrors to support directed NLOS paths. Their performance is investigated with ray-tracing simulations of a terahertz propagation channel in a dynamic office environment, which is calibrated with measured building-material and mirror parameters. We demonstrate that a directed NLOS path scheme will make a terahertz communication system robust to shadowing. Furthermore, we show that dielectric mirrors covering only parts of the walls will significantly enhance the signal coverage in a typical indoor scenario.

Short-Range Ultra-Broadband Terahertz Communications: Concepts and Perspectives

The present invention provides a high-speed electrical interconnection system designed to overcome the drawbacks of conventional interconnection systems. That is, the present invention provides an electrical connector capable of handling high-speed signals effectively.

High-speed electrical connector

Due to the broad bandwidths, terahertz (THz)-waves offer the possibility for wireless transmission of high data rates. Especially, broadband wireless access over short ranges and fixed wireless links based on THz-waves are very promising. They can be incorporated as a bridge for optical networks or an alternative for the connection of wireless stations in difficult environments, to transmit next generation HDTV signals or for the broadband connection of servers in a data center, for instance. The frequency range between 300 and 900 GHz is very promising for these applications since the possible bandwidth is very high and first electronic circuits will become available on the market soon. However, contrary to wireless links in the lower GHz-bands, the free-space path-loss is quite high and the attenuation due to molecules in the air or water droplets can significantly decrease the transmittable data rates in this frequency range. Here the basic properties of THz-waves will be investigated and the maximum achievable data rates for fixed wireless THz-links will be derived. In order to keep the considerations as general as possible, the derivations are based on simple assumptions and equations. Additionally, conclusions for the applicability of THz-waves for fixed wireless links with distances up to 1 km will be given and the special requirements for these systems will be discussed. As we will show, high data rates can only be transmitted via these links if transmitter and receiver antennas with very high gains are used. This requires an adaptive control of mechanical fluctuations.

Link Budget Analysis for Terahertz Fixed Wireless Links

A broadband power combining device includes an input port, an input waveguide section, a center waveguide section formed by stacked wedge-shaped trays, an output waveguide section, and an output port. Each tray is formed of a wedge-shaped metal carrier, an input antipodal finline structure, one or more active elements, an output antipodal finline structure, and attendant biasing circuitry. The wedge-shaped metal carriers have a predetermined wedge angle and predetermined cavities. The inside and outside surfaces of the metal carriers and surfaces of the cavity all have cylindrical curvatures. When the trays are assembled together, a cylinder is formed defining a coaxial waveguide opening inside. The antipodal finline structures form input and output arrays. An incident EM wave is passed through the input port and the input waveguide section, distributed by the input antipodal finline array to the active elements, combined again by the output antipodal finlines array, then passed to the output waveguide section and output port. A hermetic sealing scheme, a scheme for improving the power combining efficiency and thermal management scheme are also disclosed. The broadband power combining device operates with multi-octave bandwidth and is easy to manufacture, well-managed thermally, and highly efficient in power combining.

Broadband power combining device using antipodal finline structure

A power combining apparatus includes a waveguide structure and a plurality of antenna elements arranged in the waveguide structure, wherein each of the antenna elements comprises a center planar antenna layer, two outer planar antenna layers arranged on opposite sides of the center planar antenna layer, a non-conductive layer between the center planar antenna layer and one of the outer planar antenna layers, and another non-conductive layer between the center planar antenna and the other one of the outer planar antenna layers. The power combining apparatus includes a waveguide structure having an input, an output, and a plurality of antenna elements arranged in the waveguide structure, wherein each antenna element is configured to transform an electric field direction of an electromagnetic field by substantially 90 degrees rotation about a longitudinal axis of the waveguide structure, wherein a bandwidth of the antenna is less than, equal to, or greater than a decade of frequency range.

Power combiner using tri-plane antennas

This letter introduces a new wideband coplanar waveguide-to-rectangular waveguide transition. The transition uses a uniplanar circuit in line with the waveguide, which eases the design and fabrication. The design does not require airbridges. Simulations and measurements of X-band (8.2-12.4 GHz) transitions based on both a low- and high-permittivity material (/spl epsiv//sub r/= 2.33 and 10.8) show that the transition works fine over the full frequency band. For /spl epsiv//sub r/= 2.33 the measured return and insertion loss of a back-to-back transition are more than 16 dB and less than 0.4dB, respectively. The corresponding values for /spl epsiv//sub r/= 10.8 are more than 10 dB and less than 1.0 dB, respectively, over 90% of the frequency band. The measured insertion loss values indicate losses of less than 0.14 dB and 0.36 dB at the center frequency for a single transition on a substrate with /spl epsiv//sub r/= 2.33 and 10.8, respectively.

Wideband coplanar waveguide-to-rectangular waveguide transition using fin-line taper

A new coplanar waveguide (CPW)-to-rectangular waveguide transition is proposed for wide-band millimeter-wave applications. The transition has an in-line structure, which provides easy fabrication of the CPW circuit and waveguide block. An X-band (8.2-12.4 GHz) model has been designed and tested. Measurements of a back-to-back double transition have yielded a return loss of over 17 dB and an insertion loss of less than 0.5 dB over the full X-band. These results agree well with the simulated results obtained with a commercial electromagnetic structure simulator. In addition, this type of a transition has been designed and used for a local oscillator feed with a full F-band (90-140 GHz) coverage of a submillimeter-wave general-purpose harmonic mixer.

Novel wide-band coplanar waveguide-to-rectangular waveguide transition

This paper describes a process for characterisation of millimetre-wave planar diode chips. It comprises dc-characteristics, capacitance, and wide-band (7-220 GHz) scattering parameter measurements and parameter extractions from measurement results. As the first test items, we have characterised planar Schottky diode chips (varactor and mixer diodes) fabricated by Technical University of Darmstadt. We describe a coplanar waveguide test mount design applied for the measurements and show the measured and extracted results. The S-parameters at 7-220 GHz are obtained for several different bias voltages and currents.

/pdf/characterisation-of-european-millimetre-wave-planar-diodes-45wev4m74c.pdf

Characterisation of european millimetre-wave planar diodes

A new tunable waveguide backshort with low loss and reliable performance has been designed. Based on a fixed short and dielectric phase shifter, it has a simple structure which is easy to design and fabricate. These properties make it a sound alternative for millimeter- and submillimeter-wave applications. A W-band (75-110 GHz) backshort has been designed and tested showing excellent performance with a return loss of less than 0.21 dB.

http://ieeexplore.ieee.org/iel5/7260/20568/00950764.pdf

Novel tunable waveguide backshort for millimeter and submillimeter wavelengths

The design of a 215 GHz subharmonic waveguide mixer utilizing an antiparallel pair of quasivertical Schottky diodes is presented. The impedance matching is provided by series and parallel waveguide tuners. A single sideband noise temperature of 3500 K and conversion loss of 9.2 dB have been measured (antenna loss included). © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 93–97, 2000.

V.S. Mottonen

Papers

Wideband coplanar waveguide-to-rectangular waveguide transition using fin-line taper

Novel wide-band coplanar waveguide-to-rectangular waveguide transition

Characterisation of european millimetre-wave planar diodes

Novel tunable waveguide backshort for millimeter and submillimeter wavelengths

Subharmonic waveguide mixer at 215 GHz utilizing quasivertical Schottky diodes