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Sky noise measurementSky noise measurementss with a dual with a dual
polarization active dipole antennapolarization active dipole antenna
WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes
Didier CHARRIERSubatech, Nantes, France
the CODALEMA collaborationhttp://codalema.in2p3.fr
SUBATECH, Nantes
Observatoire de Paris-Meudon
Observatoire de Nançay
LAL, Orsay
ESEO, Angers
LPSC, Grenoble
LPCE, OrleansLAOB, Besançon
(FRANCE)
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 2
Active dipole antenna used for CODALEMAActive dipole antenna used for CODALEMA
Dipole antenna
Total arm length = 1.21m
Antenna height = 1m
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 3
Crossed polarised active dipole antennaCrossed polarised active dipole antenna
Same preamplifier as the CODALEMA antenna
Dual polarization
V-shape radiator made of electric wires
Total arm length = 3.22m
Antenna height = 1.40m
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 4
Measurement setupMeasurement setup
-Measurement performed in a rural area at Vairé in
Vendée (100km south of Nantes)
-Dual polarization active antenna
-Handheld spectrum analyzer R&S FSH
-24/82MHz passband filter to avoid intermodulation
created spectrum analyzer
-12V battery to supply the active antenna
LNA, 36dB
LNA, 36dB
Dual polar active
antenna under test
24-82MHZ filter15m cable
Spectrum Analyser FSH
12V battery
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 5
North South and East West spectrumNorth South and East West spectrum
Accumulation of 17 sweep
during one day LST
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 6
Galactic noise variations for few bandsGalactic noise variations for few bands
~2.3dB~2.7dB
~2.5dB
~2.7dB
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 7
Galactic noise variation for the 73/77MHz bandGalactic noise variation for the 73/77MHz band
-The measured galactic noise variation is about 2.5dB in both
polarisations from 30MHZ to 80MHZ
-This experiment should be performed with an automatic testbench to
increase the statistics, and without passband filtering.
~2.5dB
[email protected] WORKSHOP Radio@auger, January 14 and 15 2008, subatech Nantes 8
Measurement versus simulationMeasurement versus simulation
Computed sky noise
response with a NEC2
simulator and this sky
temperature data
