Andreas Penirschke

Broad-band microwave characterization of liquid crystals using a temperature-controlled coaxial transmission line

Liquid crystals (LCs) promise to be suitable passive tunable material for microwave devices with excellent features concerning tunability and losses. In order to optimize the synthesis of LCs and the design of tunable microwave devices based on them, LCs have to be characterized at microwaves. For a microwave analysis between 360 MHz-23 GHz, use was made of a broad-band characterization method with a two-port coaxial line, temperature controlled within -7/spl deg/C and 115/spl deg/C. Two LCs are investigated: K15, as a quasi-standard, and MDA-03-2838, as a novel mixture with increased dielectric anisotropy and reduced microwave losses tan/spl delta/.

Microwave Mass Flow Detector for Particulate Solids Based on Spatial Filtering Velocimetry

A novel mass flow detector has been developed using an open cylindrical resonator based on two microstrip patch couplers. The directivity of the couplers provides a compact sensor design without loss of sensitivity. The design of a particulate mass flow detector and the algorithm to detect the average solids concentration is shown. Spatial filtering velocimetry is applied to a microstrip patch sensor in order to detect the average particulate velocity. The simultaneous detection of the velocity and the solids/air concentration from a single measurement, ensure a true mass flow detector. Subsequently, free fall measurements as well as measurements in a self contained material flow measuring system were carried out in order to prove the concept.

Novel integrated coaxial line to cylindrical waveguide directive couplers in pipelines for process monitoring applications

This paper presents a novel coaxial line to circular cylindrical waveguide directive coupler, using a resonant configuration of two integrated coaxial-fed microstrip patches opposite arranged in a measurement pipeline, this configuration a directivity of more than 4 dB at 5.7 GHz can be achieved without disturbing the cross-section of the pipeline. The insertion loss of the proposed coupler is low and hence about -1 dB of the input signal is transmitted into the desired direction of the circular waveguide which is a gain of 2 dB compared to a conventional E-field probe. Similar to commercial available mass flow meters, two of these couplers, at a distance of 0.4 m in the measurement section, form a mass flow sensor (Penirschke et al., 2004).

New Microwave Flow Sensor based on a Left-Handed Transmission Line Resonator

This paper presents a new material density sensor for process monitoring applications based on a composite right/left-handed transmission line resonator. Compared to a conventional right-handed line resonator an increased sensitivity could be demonstrated by measurements of a prototype. The presented sensor principle promises the possibility to design precise permittivity sensors with low to moderate costs. The areas of application of such sensors are gas/solids, gas/liquid and liquid/solids flows in various industrial applications.

Microwave Sensor for Accurate Material Density Measurements of Gas/Solid flows in Pipelines

This paper presents a novel material density sensor based on two novel microstrip-patch (MSP) couplers for process monitoring applications. The sensor is designed to detect gas/solid flows, especially for very low solid concentrations without changing the flow distribution and the velocity profile in the pipeline. The couplers exhibit low insertion losses and distinct transmission maxima that extent a high sensitivity of the sensor system. Measurement errors below plusmn2.5% relating to the instantaneous value could be archived for solid concentrations from 0.064% (vol.) up to 0.25% (vol.) (Penirschke and Jakoby, 2006). The investigation of the measurement errors shows that the sensor accuracy can be increased still further by a reduction of the temperature influence to the sensor

High bandwidth pickup design for bunch arrival-time monitors for free-electron laser

In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor designed for high ( > 500 pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A nonhermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

Helix-shaped CRLH-mass flow detector for the cross-sectional detection of inhomogeneous distributed pneumatic conveyed pulverized solids

This paper presents an application of a Composite Right/Left-Handed (CRLH) Transmission Line resonator for a compact mass flow detector with increased sensitivity compared to a conventional microwave mass flow detector. In this concept series capacitors and shunt inductors are used to synthesize a medium with simultaneously negative permeability and permittivity — the so called metamaterial. The simultaneous detection of the velocity and solids/air concentration from a single measurement, ensures a true mass flow detector. The rearrangement of two CRLH-TL resonators to a helix shape opens the possibility to detect the cross-sectional flow distribution of the fed material in order to increase the accuracy of the detector. A prototype was realized and tested in a dedicated measurement setup to prove the concept. The application areas of this sensor are gas/solids, gas/liquid and liquid/solids flows in various industrial monitoring applications.

Dual mode sensor for belt conveyor systems based on planar metamaterials

A new sensor concept has been developed using a metamaterial transmission line with two different operation modes for the simultaneous detection of material permittivity and position. In the first mode the sensor is used as a resonator and the permittivity is detected accurately and with a moderate cost. On the second mode the sensor is used as a transmission line and the spatial material distribution is detected using time domain reflectometry techniques. A prototype sensor has been realized and tested in a dedicated measurement setup. The areas of application of these types of sensors are material monitoring during transportation in conveyor belts for several industrial processes.

Microwave mass flow sensor for process monitoring applications

A particulates mass flow meter has been developed using a cylindrical waveguide resonator. Two directional MicroStrip-Patch couplers confine the resonant measurement section of the sensor without any disturbance of the material flow in the pipeline. A new extraction algorithm has been introduced to detect the material concentration and the velocity of particulate solids out of a single time continuous measurement. The autocorrelation function and the pre-knowledge of the time dependent phase shift, when particles flying through the sensor, where used for precise particle velocimetry. Measurements with a built up sensor at 5.5 GHz where carried out to prove the concept. Application areas of this sensor type are gas/solids, gas/liquid and low loss liquid/solid flows in various industrial applications.

W-Band Characterization of Anisotropic Liquid Crystals at Room Temperature

This paper describes the characterization of Liquid Crystals (LCs) at W-Band using the standard WR-10 rectangular waveguide. The reflection parameter of a 10 mm long waveguide - terminated by a short-circuit - is measured. The LC is oriented with a homogeneous magnetostatic field strength of 400 A/mm, generated with an air-cooled coil. The extracted complex permittivity of the LC K15 from Merck KgaA (also known as 5CB) is presented, showing permittivities well below 3 with a dielectric anisotropy of Deltaepsiv<0.19 (equivalent to tau=Deltaepsiv/epsivmax<8.5%) and dielectric losses less than tandelta<0.023, all at W-Band.