compact 3d-printed variable-infill antenna for snow cover ......compact 3d-printed variable-infill...

Compact 3D-printed Variable-infill Antenna for Snow Cover Monitoring

P. F. Espin-Lopez1, M. Pasian1

1 Dept. of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy,[email protected]

[email protected]

Relatore

Note di presentazione

Good morning, thanks to the session chair for the introduction. My name is Pedro Espin-Lopez and I’m going to talk about the conference paper called “Compact 3D-printed Variable-infill Antenna for Snow Cover Monitoring”, the authors are Marco Pasian and myself, both from the Department of Electrical, Computer and Biomedical Engineering of the University of Pavia in Italy. This paper presents the development and the experimental results of a novel antenna realized by 3D printing techniques for snowpack monitoring. In presentation I will use the word ‘snowpack’ instead of ‘snow cover’ to avoid confusion with the satellite remote sensing of the snow cover, which is a completely different technique that the one used in this work. So, the snowpack is the seasonal accumulation of packed snow composed by an aggregate of snow layers with different micro and macrostructures. This work is part of the 3-years national funded project called SNOWAVE which has the purpose of give a substantial contribution to more precise and reliable avalanche prediction, studying an innovative microwave based solution for automatically monitoring the snowpack internal structure.

Alpine Regions

Motivation

Affected by snow avalanches

100 millions tons of goods

20 millions tourists

22 millions residents

avg. 100 deaths per year

Structural defense > 100 M€/y

Damage (y. 1999) ≈ 1000 M€

Source: Centre for Climate Adaptation, www.climateadaptation.eu EU FP5 SATSIE, Avalanche studies and model validation in Europe

Avalanche Forecasting

Information about the Snowpack

Manual Stratigraphy

Compact 3D-printed Variable-infill Antenna For Snow Cover Monitoring - P.F Espin-Lopez and M. Pasian - EuCAP 2018

Relatore

Note di presentazione

The aim of Snowave as I previously said is to design a microwave system for avalanche forecasting. And why is necessary to do avalanche forecasting? Well, in this slide I want to throw some numbers to highlight the importance of this task. Snow avalanches are a persistent risk for mountain countries all around the world, threatening the safety of residents and winter tourist. Focusing on the Alps, and consequently on the alpine regions, the number of residents is 22 millions while the number of winter tourist in the Alps is estimated in 20 millions per year. It is importance also to notice that around 100 millions tons of goods go through the alpine regions each year and are also very vulnerable to traffic interruptions caused by snow avalanches. The expenses in Structural defences for snow avalanches is higher than 100 millions of euros per year, and the damages in 1999 which was a record year reached the 1000 millions of euros. Finally, and for sure the most critical result of snow avalanches is that every winter around 100 people (skiers, alpinists, tourists or residents) lose their lives because of a snow avalanche in the alpine arc.

http://www.climateadaptation.eu/

Motivation

Manual Snow Stratigraphy

Avalanches: Instability at the interface between different snow layers.Snow stratigraphy crucial for avalanche forecasting and risk-managementManual stratigraphy is widely accepted as forecasting method

no real time – 7d/15d repetition timerarely on steep slopes – logistic and safety

problemsexpensive – time consuming, 2/3 profiles per

dayno during adverse weather – impossible,

dangerous

Not available when and where MOST NEEDED

Microwave Radar

Systems for Snowpack Monitoring

[1]-[5][1] Marshall, 2008[2] Atayants, 2014[3] Schmid, 2014[4] Frey, 2015[5] Rekioua, 2015


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Antenna Specifications

Microwave FMCW Radar System presented in [*]

D ⁓ 1-2 m in Alpine Regions

S ⁓ 0.3-1 m for Optimization [*]

Snow Density (kg/m3)

LWC (%)

[*]

ε ' ε ''

dry 90 – 450 ~ 0 1.2 –1.8 ~ 0

wet 400 –700

3 –12

2.1 –4.3

0.03 –0.21

Ice 800 –900 ~ 0 ~ 0

For microwave radars aimed at snowpack monitoring, low frequencies are preferred to provide an adequate penetration depth, even in the presence of moderately wet snow [*]

Up to C band

Snow density, Liquid Water Content (LWC) and dielectric permittivity at 1 GHz for typical alpine snow [**]

*P. F. Espin-Lopez, M. Pasian, M. Barbolini, and F. Dell’Acqua, “Optimization of a multi-receiver FMCW radar for snow cover monitoring”, 12th European Conference on Antennas and Propagation (EuCAP 2018), London, UK, 9-13 April 2018.**M. T. Hallikainen, F. T. Ulaby, and M. Abdelrazik, “Dielectric properties of snow in the 3 to 37 GHz range,” IEEE Transactions on Antennas and Propagation, Vol. 34, No. 11, pp. 1329–1340, November 1986.

Ground or Air

Ground or Air

2.9




S ⁓ 0.3-1 m for Optimization

Radar Resolution

𝜁𝜁 =𝑣𝑣2𝐵𝐵

v = wave speed into the mediumB= radar bandwidth

⁓5 cm layers

Bandwidth > 3 GHz

Wide BeamwidthSnowpack




S ⁓ 0.3-1 m for Optimization

Radar Resolution

𝜁𝜁 =𝑣𝑣2𝐵𝐵

v = wave speed into the mediumB= radar bandwidth

⁓5 cm layers

Bandwidth > 3 GHz

Wide BeamwidthSnowpack

-Frequency band up to C band-Bandwidth > 3 GHz-Wide Beamwidth Antenna-Reduced volume and weight

In Summary


Premix Preperm® 3D ABS

-Special 3D filament -2.85 mm Ø-Based on ABS thermoplastic polymer-ε’r = 4.5 @1GHz-tan δ = 0.004 @1GHz-Can be printed with a FDM machine


Premix Preperm® 3D ABS

-Special 3D filament -2.85 mm Ø-Based on ABS thermoplastic polymer-ε’r = 4.5 @1GHz-tan δ = 0.004 @1GHz-Can be printed with a FDM machine

Very Low Losses!!&

Design freedom


DRW Antenna Design

- Double Ridge Waveguide Open-ended Antenna- 3D printed using Premix Preperm 3D ABS- 5.16 x 2.40 x 6.78 cm- SMA connector- Variable infill- Tapered ridges


DRW Antenna Design

Simulated input matching of the proposed antenna with variable infill (solid curve) and with constant infill (dashed curve).

Inpu

t Mat

chin

g (d

B)


DRW Antenna Design

Simulated input matching for the proposed DRW antenna fordifferent snow conditions (ε' = 1.2–4.3).

Inpu

t Mat

chin

g (d

B)


Antenna Realization

3D printed antenna (Premix Preperm)

Conductive silver-based paint

Copper electrodeposition

Fabrication Process


Antenna Realization

Input matching: simulated (solid curve) and measured (dots).Keysight N9928A Virtual Network Analyzer in anechoic chamber and a standard certified probe antenna

Inpu

t Mat

chin

g (d

B)


Antenna Realization

Normalized radiation patterns: (top) H-plane (bottom) E-plane at the central frequency of 4.15 GHz. Simulated co-polarization (solid line) and crosspolarization (dashed line), along with measured co-polarization (dots) are reported.

Normalized radiation patterns: (top) H-plane (bottom) E-plane at 2.48 GHz (solid black line), 3 GHz (solid dark grey line), 4 GHz (solid light grey line), 5 GHz (dashed black line), and 6 GHz (dashed light grey line).


Antenna Realization

Simulated (solid curve) and measured (dots) for the peak gain.

Keysight N9928A Virtual Network Analyzer in anechoic chamber and a standard certified probe antenna

Immagine Camera


Antenna Realization

Summary- Input matching better than -6 dB from

2.3 GHz to 6 GHz (BW-6dB=3.7 GHz).- Gain of 5 dBi at the central

frequencies.- 5.16 x 2.40 x 6.78 cm3 for 100 g of

mass, robust design and durable materials.


Conclusions

- A novel Double Ridge Waveguide Antenna suitable for snowpack monitoring was designed, fabricated and measured.

- Intended both for portable and permanent applications.

- Realized with 3D printed techniques using the ultra low loss filament Premix Preperm 3D ABS.

- The antenna will be tested on the field in the next days and seasons.


References

[1] H.-P. Marshall and G. Koh, “FMCW Radars for snow research,” Cold Regions Science and Technology, Vol. 52, pp. 118–131, 2008.[2] B. A. Atayants et al., Precision FMCW short-range radar for industrial applications, Artech House, 2014.[3] L.Schmid, et al., “Continuous snowpack monitoring using upwardlooking ground-penetrating radar technology,” Journal of Glaciology, Vol. 60, No. 221, pp. 509–525, 2014.[4] O. Frey, C. L. Werner, and A. Wiesmann, “Tomographic profiling of the structure of a snow pack at X-/Ku-Band using SnowScat in SAR mode,” 2015 European Microwave Conference, Paris, France, September 6–11, 2015.[5] B. Rekioua, M. Davy, and L. Ferro-Famil, “Snowpack characterization using SAR tomography – experimental results of the AlpSAR campaign,” 2015 European Radar Conference, Paris, France, September 6–11, 2015.


THANKS!


Appendix I

compact 3d-printed variable-infill antenna for snow cover ......compact 3d-printed variable-infill...

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