research activities of the imp utilizing cst microwavestudio€¦ · research activities of the imp...

29.03.2013 | ETiT | Institute of Microwave Engineering and Photonics | Matthias Hansli | 1

Research activities of the IMP utilizing CST MicrowaveStudio

European User Conference 2013


Outline

Varactor design based on a tunable ceramic Alex Wiens et al.

Tunable polarizer based on Liquid Crystal (LC) Sebastian Strunck

Cavity sensor for Schottky measurements at particle accelerators

Varactor Design based on a tunable ceramic


Varactors are part of tunablematching networks e.g. π-network

Multi-band/multi-standard requirementsWifi, LTE, UMTS etc.Software defined radio

Aim: Multi-band coveragewith single transistor type

Varactor Design: Barium-Strontium-Titanate

Ceramic materialNonlinear polarization

dependent on electricalfield


Metal

Alumina

BST

Varactor Design on BST Thick Film

Varactor realized as Inter-Digital-Capacitor integrated DC Bias-NetworkAim: high tunability (ΔC/ΔUBias )


Varactor Design: Simulation

Varactor Model construction Electrostatic solver on a homogenious

substrate Local field analysis Construct tuned substrate based on a

BST tunability model RF simulation to extract S-Parameter


Varactor Design: Macro for tuned substrate



Outline




Tunabel polarizer based on Liquid Crystal (LC)

Liquid crystalUniaxial crystals anisotropic material nemantic phase



Elliptical Waveguide, twisted 90°



Cylindrical waveguide filled with LC Orientation of LCs causes „electrically elliptical“ waveguide Aim: high transmission and low polarization crosstalk Need for a full tensor material



Expansion of the „Create full tensor material“-macro allows creation of multiple slices with certain thickness and rotation angle



Simulation at 50 GHz 90° Twist of Polarisation, 20 LC elements providing a per step rotation of

4,5°.



Outline




Cavity sensor for Schottky measurements

Goal: “Design a Schottky Sensor with very high sensitivity to detect smallest beam-currents down to single particles for the Collector Ring at FAIR.”

Schottky Noise: Current fluctuation caused by the discrete charge carriers Gives insight about the energy/frequency distribution of the particles

Cavity is used as a resonant sensor


Cavity Sensor: Principle

Charged particles couple to E-field Circular waveguide resonator – „pillbox“ First two modes with E-Field in direction of particle movement Excitation of monopole mode around 10^4 times stronger


Dipolmode - TM110Monopolmode - TM010

Cavity Sensor : Pillbox


Pillbox cavity

couple slot

Nose

cavity length

radius

length (z) &heigth (radial)

Cavity Sensor: Waveguides


waveguides/resonators

coupling slots(length & width)

length

width

heigth

Cavity Sensor


Cavity Sensor: Eigenmodes

Monopole mode not expanded intowaveguides

Dipole mode expandedinto waveguides

29.03.2013 | ETiT | Institute of Microwave Engineering and Photonics | 21

Cavity Sensor: Optimization

Matlab is used to control MWS Optimization of R/Q-value with the Eigenmode Solver R/Q is a measure for the energy transfer between particle and cavity dependent on geometry only differrent geometry for the nose Monopole mode frequency is kept as 200 MHz by adjusting the cavity radius

Different dimensions of coupling slot detune cavity modes and waveguideresonator eigenmode frequencies Monopole mode at 200 MHz again with adjusting cavity radius Waveguide length optimized to scope with changed dipole mode frequency


Cavity Sensor: Optimization

Matlab is used to control MWS Optimization of R/Q-value with the Eigenmode Solver R/Q is a measure for the energy transfer between particle and cavity dependent on geometry only differrent geometry for the nose Monopole mode frequency is kept as 200 MHz by adjusting the cavity radius Different dimensions of coupling slot detune cavity modes and waveguide

resonator eigenmode frequencies Monopole mode at 200 MHz again with adjusting cavity radiusWaveguide length optimized to scope with changed dipole mode frequency

29.03.2013 | ETiT | Institute of Microwave Engineering and Photonics | 23

Cavity Sensor: Measurement vs. Simulation


Thank you.

The work presented in this slides was done by Alex Wiens and Holger Maune et al. , Sebastian Strunck et al. and Matthias Hansli et al.


research activities of the imp utilizing cst microwavestudio€¦ · research activities of the imp...

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