Sky noise measurements with a dual polarization active dipole antenna

Sky noise measurement
s

with a dual
polarization active dipole antenna

WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


Didier C
HARRIER

S
ubatech, Nantes, France

Didier.charrier@subatech.in2p3.fr

the
CODALEMA

collaboration

http://codal
e
ma.in2p3.fr

SUBATECH, Nantes

Observatoire de Paris
-
Meudon

Observatoire de Nançay

LAL, Orsay

ESEO, Angers

LPSC, Grenoble

LPCE, Orleans

LAOB, Besançon

(FRANCE)

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


2

Active dipole antenna used for CODALEMA

Dipole antenna

Total arm length = 1.21m

Antenna height = 1m

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


3

Crossed 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

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


4

Measurement 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 filter

15m cable

Spectrum Analyser FSH

12V battery

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


5

North South and East West spectrum

Accumulation of 17 sweep

during one day LST

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


6

Galactic noise variations for few bands

~2.3dB

~2.7dB

~2.5dB

~2.7dB

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


7

Galactic noise variation for the 73/77MHz band

-
The measured g
alactic 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

didier.charrier@subatech.in2p3.fr WORKSHOP Radio@auger
, J
anuary

1
4 and
15 200
8
,
subatech Nantes


8

Measurement versus simulation

Computed sky noise
response with a NEC2
simulator and this sky
temperature data