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Selected Applications of Tunable Materials for Microwave Components
Matthias Maasch, Onur Hamza Karabey, Sebastian Strunck and Rolf Jakoby
Mircowave Engineering, Technische Universität Darmstadt
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 2
Tunable Materials for Microwave Components
Phase shifter in antenna arrays for beam forming
Matching networks
Power amplifiers
Implementation of tunability by using
Liquid Crystal above 10GHz
Ferroelectrics (Barium-Strontium-Titanate) below 15GHz
Metamaterials
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 3
Outline
Coaxial Transmission Line for Liquid Crystal Charaterization
Thermal Effects in Interdigital Capacitors
Tunable SRR loaded Waveguide
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 4
Coaxial Transmission Line for Liquid Crystal Charaterization
Thermal Effects in Interdigital Capacitors
Tunable SRR loaded Waveguide
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 5
LC Characterization Setup
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 6
LC Characterization Setup
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 7
10 20 30 40 50-5
-4
-3
-2
-1
0
f (GHz)
|S2
1|/d
B
no EM leakage
incl. EM leakage
EM Leakage through Filling Channels
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 8
Simulated Impact of Filling Channels
Karabey et al. “Precise Broadband Microwave Material Characterization of Liquids” EuMW 2010
Error due to EM leakage: r’ : <6% r’’ : <40%
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 9
Coaxial Transmission Line for Liquid Crystal Charaterization
Thermal Effects in Interdigital Capacitors
Tunable SRR loaded Waveguide
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 10
Interdigital Capacitor on BST
r of BST is tunable by static E-field
Cheap printing technology
Better linearity compared to semiconductor varactors
High power capability ‟ thermal effects?
Alumina (250µm)
BST (10µm)
Gold (3µm)
Gold (3µm)
+VDC
-VDC
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 11
Simulated Temperature
IDC size: 200x600µm2
Gap width: 20µm
Finger width: 20µm
BST RF properties
r = 200, tan = 0.02
RF input power:50W @ 2GHz
Maximum temperature ≈ 52°C
Temperature inside BST layer ≈ 37°C
He “Heat capacity, thermal conductivity, and thermal expansion of barium titanate-based ceramics” Thermochimica Acta, 2004
BST
Alumina
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 12
Coaxial Transmission Line for Liquid Crystal Charaterization
Thermal Effects in Interdigital Capacitors
Tunable SRR loaded Waveguide
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 13
Tunable SRR loaded Waveguide
Maasch et al. “Voltage Tunable Split-Ring-Resonators for Waveguide Applications” Metamaterials 2009
Introduction of tunability to Split Ring Resonators by loading the gap
Phase shifter, filter inside a waveguide
Step towards voltage tunable 3D Metamaterial
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 14
DC-Biasing of SRR Array
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 15
Simulated Impact of Bias Elements
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 16
Simulation of Tuning
theoretical tuning range: 0.7…2.4GHz
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 17
Measurement Setup
9 SRRs with 9x9mm2
Substrate: RT/duroid 5880, t=0.38mm
Biasing Resistor
Varactor Diode
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 18
Measurement Results
measured tuning range: 0.9…2.2GHz
ETiT | Mikrowellentechnik „ Microwave Engineering | CST User Group Meeting 2010 | 19
Thank you for your attention.
