AAVS0 Results,
Dual-Polarized Vivaldi Antenna
G. Virone, R. Tascone, A. Olivieri, O.A. Peverini, G. Addamo
F. Perini*, M. Schiaffino*, J. Monari*, G. Bianchi *, S. Montebugnoli*
*Istituto di Radio Astronomia
Istituto Nazionale di Astro Fisica
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Dual-pol Vivaldi 50 Ohm ver1
• Maximum size 1.1 m
• Metal-only
• 50 Ohm unbal impedance
• No additional ground plane
• Very Low Cross-Pol
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Feed Configuration and Labeling
Front
Probe
Back
Probe
Housing for Electronics
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Manufacturing
-First Prototype
-Laser cutting machine
-Multi-layer alluminum prototype
Laser cutter
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
VNA Reflection Measurement
Reference Impedance = 50 Ohm
0
-2
Back
Front
Back
Front
-4
Reflection (dB)
-6
Probe (Sim)
Probe (Sim)
Probe (Meas)
Probe (Meas)
-8
-10
-12
-14
-16
-18
-20
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Frequency (GHz)
CNR IEIIT – Applied Electromagnetics Group
0.4
0.45
0.5
AAVP, Dwingeloo, December 12-16 2011
Radiation Pattern Measurements
Outdoor Elevated Antenna Test Range (Turin, July 2011)
H-plane @180 MHz
0
0
0
-10
-20
Gain (dB)
10
-30
-10
-20
-100
-30
0
100
Theta (Deg)
E-plane @70 MHz
-10
-20
-100
-30
0
100
Theta (Deg)
E-plane @180 MHz
10
0
0
0
-20
-30
Gain (dB)
10
-10
-10
-20
-100
0
100
Theta (Deg)
-30
CNR IEIIT – Applied Electromagnetics Group
-100
0
100
Theta (Deg)
E-plane @450 MHz
10
Gain (dB)
Normalized Gain (dB)
H-plane @450 MHz
10
Gain (dB)
Normalized Gain (dB)
H-plane @70 MHz
10
-10
-20
-100
0
100
Theta (Deg)
-30
-100
0
100
Theta (Deg)
AAVP, Dwingeloo, December 12-16 2011
From Version 1 to Version 2
Good matching in the 70-450 MHz band
Acceptable matching in the 70-450 MHz band
Low directivity at 45° in E-plane
High back lobe
CNR IEIIT – Applied Electromagnetics Group
Higher directivity in the ±45° sky coverage
Lower back lobe
AAVP, Dwingeloo, December 12-16 2011
Vivaldi Aeff/Tsys for each polarization
Number of elements = 1e6
Aeff/Tsys [m2/K]
3000
2000
Zenith v1
Zenith v2
1000
Theta=0°
0
0.1
0.15
0.2
0.25
0.3
Frequency (GHz)
0.35
0.4
0.45
Aeff/Tsys [m2/K]
3000
Eplane 45 Deg v1
Hplane 45 Deg v1
Eplane 45 Deg v2
Hplane 45 Deg v2
2000
1000
Theta=45°
0
0.1
0.15
0.2
0.25
0.3
Frequency (GHz)
CNR IEIIT – Applied Electromagnetics Group
0.35
0.4
0.45
AAVP, Dwingeloo, December 12-16 2011
Effect of the Soil
Directivity @ 100 MHz (H-plane)
10
ICRAR Soil DATA
5
0
Directivity (dB)
Permittivity (Real Part)
12
Soil A
Soil B
Soil C
10
08
-10
-15
Radiation Efficiency = 0.7
-20
6
-25
4
-30
-5
0.1
0.2
0.3
Frequency (GHz)
0.4
-50
0
50
Theta (Deg)
100
150
Directivity @ 450 MHz (H-plane)
0.06
-15
0.04
0.02
5
0
Directivity (dB)
Free Space
Soil A
Soil B
Soil C
Soil A
Soil B
Soil C
0.08
-5
-10
-15
-20
-20
-25
-100
10
-10
0
-150
0.5
0.1
Reflection
Coefficient
Conductivity
(S/m) (dB)
-5
-25
0.1
0.2
0.3
Frequency (GHz)
0.4
Rad. Eff. = 0.92
0.5
CNR IEIIT – Applied Electromagnetics Group
-30
-150
-100
-50
0
50
Theta (Deg)
100
150
AAVP, Dwingeloo, December 12-16 2011
Computation of TantGnd
300
Soil A (Full Wave)
Soil B (Full Wave)
Soil C (Full Wave)
TantGnd (Far-Field)
Noise Temperature (K)
250
200
Tantgnd = T0 (1-ηR)
T0 = 290 K
TantSky (Far-Field)
150
100
50
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Frequency (GHz)
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Gain vs Frequency
BroadBand Gain (dB)
10
Free Space
Soil B
8
6
4
Gain (dB)
2
0
-2
-4
-6
-8
-10
0.1
0.15
0.2
0.25
0.3
Frequency (GHz)
CNR IEIIT – Applied Electromagnetics Group
0.35
0.4
0.45
AAVP, Dwingeloo, December 12-16 2011
Hexacopter Far-Field Measurements (1)
Collaboration with DITAG, Politecnico di Torino
http://www.mikrokopter.de
Telemetry and GPS
Hexacopter Battery
RF TX and
additional battery
Bow-tie antenna
Optical Scatterer
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Hexacopter (2)
• FF Pattern measurement in
the operative condition
(ground, small array)
• Meas. range > 60 m
• GPS Accuracy : 0.5 m-> 1 cm
• Total Station Accuracy: 5 mm
• GPS-sync spectrum analyzer
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Low-cost Manufacturing
Mini-production of (48) Vivaldi, with 2cm
honeycomb (used for High speed NL trains)
Target Cost
200€ x
antenna
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
Optical Self-Powered Vivaldi
-
Galvanic isolation between FE and DS
more stable amplitude&phase Vs temperature
RFI immunity (self-shielded)
no Gain disequalization
no Power Distribution  no DC power losses
easy-deployable (no buried FO)
We have 0.15 m2 maximum
available area per arm.
BATTERY
Front End
Thin film (amorphous silicon )
CNR IEIIT – Applied Electromagnetics Group
That area could be sufficient,
but we need more investigation
and tests on the field.
AAVP, Dwingeloo, December 12-16 2011
Conclusion
• Experimental results confirmed the computed
data of the Dual-Pol Vivaldi v1.
• An improved version (v2) has been designed
(AAVS0) and manufactured (4 x 4 array)
• Simulations of the soil ground effect confirm the
performance (without additional mesh)
• A new measurement setup is being developed
• Industrialization process is in progress
• Optical Self-powered element
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
CNR IEIIT – Applied Electromagnetics Group
AAVP, Dwingeloo, December 12-16 2011
3 x 3 Regular Array Simulation
Element Spacing is 1.5 m
Reference Impedance = 50 Ohm
0
Reflection Coeff. (single element)
Reflection Coeff. (embedded element)
Mutual Coupling H-plane
Mutual Coupling E-plane
Reflection & Coupling (dB)
-5
-10
-15
-20
-25
-30
-35
-40
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Frequency (GHz)
CNR IEIIT – Applied Electromagnetics Group
0.4
0.45
0.5
AAVP, Dwingeloo, December 12-16 2011
VNA Coupling Measurement
Reference Impedance = 50 Ohm
-20
Simulated
Measured
Cross Coupling between ports (dB)
-25
-30
-35
-40
-45
-50
-55
-60
-65
-70
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Frequency (GHz)
CNR IEIIT – Applied Electromagnetics Group
0.4
0.45
0.5
AAVP, Dwingeloo, December 12-16 2011