Why Radio? Why something new? Choice of antenna Background Sensitivity Self-Trigger Future

Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft

Advanced Detection of Radio Signals from Cosmic Rays for KASCADE Grande and Auger

(with Self Triggered Array of Radio-detectors (STAR))

Why Radio?

Why something new?

Choice of antenna

Background

Sensitivity

Self-Trigger

Future

• Cheap detectors, easy to deploy

• Duty cycle 24 hours/day

• Practical no attenuation

• Bolometric measurement – integral of EM-signal over shower

evolution

• Also for neutrinos

• Potential problems: – Radio Freq. Interference (RFI)

– trigger by lightning (as FD)

– only practical above ~1017 eV


17.05.2005 Hartmut Gemmeke, IPE, ARENA 2005 2

a. requirements: - bandwidth: 40 MHz to 80 MHz- good polarisation detection: north-south, east-west,

circular- beam width (-3dB): -60°. . . +60° (at Karlsruhe),

-80°...+80° (at Auger)- high 90° and backward attenuation- reasonable precision for

impedance: frequency independent -> real- simple calibration- bull-proof, wind-proof, low cost, simple assembly

b. Considered antennas

- V-dipole (LOFAR)

- Logarithmic periodic conical helix (CODALEMA)

- Logarithmic periodic dipole antenna (STAR)

Choice of antenna for STAR

E measurement :

E 15% ?



What I know about LOPES V-dipole

• f[MHz] 40 ... 80 [m] 7.5... 3.75

• l/ < 1/4

• Impedance 55MHz 12.5 - j 150• impedance matching to keep best timing information

• reflectivity r: Bothe 45

-> |r| > 50%, ??? precision & sensitivity ???

• this antenna is optimized for LOFAR but not for STAR?

h

l/2

ln(1/ r )0

d

RpCp

a) h =/8, b) h =/4, c) h =3/8, d) h =/2

For straight dipole over ground, depends on of ground and f !!!



Logarithmic periodic antennas• Conical helix (tested also at Ka)

Large Helix, 4 x 4 x 5 m3, nice: – more complicated to build and

– crosstalk between both polarisations -> no further considerations

• Surviving: Logarithmic periodic dipole antenna (LPDA)



2 identical LPDAs mounted orthogonally on a shared pole <-> 2 polarizations

Bandwidth: 35…90 MHz Gain: 5.5 dBi Impedance: 50 Ohm Coax Return loss: - 12 dBBeam width [-3dB]: 50° (E-Plane)

70° (H-Plane)Backward attenuation: 20 dB± 90°-attenuation: 20 dB (E-Plane)

6 dB (H-Plane)Polarisation isolation: > 20 dBSize (without pole): 4 x 4 x 3 m3

Weight (without pole): 15 kgAntenna Station on IPE building (south)

Crossed logarithmic-periodic Dipole Antenna

Lightning protection

preamplifier



Logarithmic-Periodic Dipole Antenna

0

0,2

0,4

0,6

0,8

10

10 2030

4050

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310320

330340 350

36 MHz

50 MHz

66 MHz

100 MHz

Beam width [-3 dB]: 50°

Backward attenuation: 20 dB

90°-attenuation: > 20 dB

E-Plane directional diagram of LPDA



Beam width [-3 dB]: 70°

Backward attenuation: > 15 dB

90°-attenuation: 6 dB

Logarithmic-Periodic Dipole Antenna Directional Diagram, H-Plane

0

0,2

0,4

0,6

0,8

10

10 2030

4050

60

70

80

90

100

110

120

130140

150160170

180190200

210220

230

240

250

260

270

280

290

300

310320

330340350

36 MHz50 MHz66 MHz100 MHz

H-Plane directional diagram of LPDA



Logarithmic-Periodic Dipole Antenna Return Loss (50 Ohm)

-25

-20

-15

-10

-5

0

35 40 45 50 55 60 65 70 75 80

Frequency [MHz]

S11

[d

B]

Real impedance

Return loss (50 ): < -12 dB

94 % of the antenna signal power accepted by receiver

Return loss of LPDA



V-dipol

Capacitive impedance

difficult matching

r > 50% -> don’t match: current

f-dependance

Very simple to build but not for the case top on a pole (ground plane)

High wind-load at 200km/h?

Bad side & backward attenuation

-> needs a well defined ground plane

Polarisation needs good calibration from antenna to antenna

Why not V-DipolLogarithmic-Periodic Dipole Antenna

Real impedance 60

simple matching

very small reflectivity r < 10% (<12dB)

negligible f-dependance

Simple to build also on top of a pole

Low wind-load at 200km/h

Very good side & backward attenuation(necessary because of noise from surface detectors of Auger)

-> needs not a well defined ground plane

Relative calibration is mostly given by construction -> polarisation measurement easy



VME, 6HE/160mm, 8 Channels, 3.3V(160mA), 65 mW/Channel From antenna to ADC 50 ohm design

Analog RF Front End

pos. envelope

neg. envelope

radio frequency

BIAS-T

20 dB NF 1,8dB± 0,4 V

RG214 100 m

pos. envelope

neg. envelope

radio frequencyRG214 100 m

BIAS-Tpos. envelope

neg. envelope

radio frequency20 dB NF 1,8dB± 0,4 V

RG214 100 m

BIAS-Tpos. envelope

neg. envelope

radio frequency20 dB NF 1,8dB± 0,4 V

RG214 100 m

CH 5

CH 6

CH 7

CH 8

20 dB Dual LNANF 1.8 dB3,3V (22mW/Channel)

Cro

ss

ed

LP

DA

Cro

ss

ed

LP

DA

1 Vpp / 50 Ohm

ADCs

BIAS-T

LNA-Supply

40 MHz 8th order

80 MHz 8th order ± 0,4 V 20 dB 20 dB

40 MHz 8th order

80 MHz 8th order

BIAS-T

LNA-Supply

40 MHz 8th order


40 MHz 8th order

80 MHz 8th order

BIAS-T

LNA-Supply

40 MHz 8th order


40 MHz 8th order

80 MHz 8th order Rectifier

Rectifier

Rectifier

BIAS-T

LNA-Supply

40 MHz 8th order


40 MHz 8th order

80 MHz 8th order Rectifier

BIAS-T

20 dB NF 1,8dB± 0,4 V



Filtering and Amplification

-80-70-60-50-40-30-20-10

010203040506070

0 20 40 60 80 100 120 140 160 180 200

Frequency [MHz]

Gai

n [

dB

]

Filtering and Amplification

Band-pass Filter 32th order !

Pass-band

Gain (41…79 MHz): + 55 dB

Loss by 100m cable - 5 dB

Ripple (41…79 MHz): ± 3 dB

Slope: 10 dB/MHz

Stop-band

Short Wave Attenuation: -110 dB

FM Radio Attenuation: - 90 dB

VHF Attenuation - 80 dB



Filtered Antenna Signal with Crossed LPDA

FM radio, short wave and VHF are well rejected by the band-pass filter (32th order)

Within 40…80 MHz band an ARD TV Transmitter is located:

- Raichberg, Schwäbische Alb

- ARD, channel E04, 100 kW

- Video carrier: 62,25 MHz

- Audio carrier: 67,75 MHz

- with V-Dipol (LOPES) 10 dB larger interference signal

Interference rejection by filtering

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

0 20 40 60 80 100 120 140 160 180 200

Frequency [MHz]

Pow

er [d

b]

filtered unfiltered

FM RadioShort Wave

Airplane

Amateurs

Police

VHF TVTV Transm.Raichberg

32th order band pass filter



-140

-130

-120

-110

-100

-90

-80

-70

10 30 50 70 90 110 130 150 170 190 210

f[MHz]

E[d

Bm

]

Near Tank TATO Pampa Tank TATO Pampa at night Pampa no Antenna

Radio background at Auger20 to 30 dB better than at Karlsruhe !!!



AD-Conversion and circular buffer (test system)

• Self designed ADC- and Circular-Buffer-System planed until end of 2005

• Standard VME DAQ-System• 16 Channels, 12 Bit, 80 MSample/s

• Circular Buffer, 2 x 128 kSample/Channel (trigger = freeze)

• Data Transfer, optical VME-PCI Interface



h = 56 m

human made Interference from the horizon

Pulses from the horizon ( = 90°, interference sources) have a delay of: T ≥ h / c = 190 nsproblem: if source of interference is inside the triangle !!

Pulses with higher elevation < 80 (e.g. from air showers) reach the antennas more simultaneously: 0 < T < 190 ns

65 m

Self trigger: Coincidence of three antennas

Mono-Flop 190 ns

Envelope A1

THR

+

-

Mono-Flop 190 ns

Envelope A2

THR

+

-

Mono-Flop 190 ns

Envelope A3

THR

+

-

= 3



Envelope

RF Signal20 mV

5 mV200 ns

Triggering with envelope signals

• Envelope signals are generated by the analog RF front end

• Advantage:

– continuous RF -> shift of DC offset and -> easily rejected

• Threshold 20mV:

– Single rate KA < .2 Hz

– Coincidence rates mHz



north

east

south

north + east + south but T > 190 ns no trigger

10 mV200 ns

Usable threshold 10 mV

Radio field-strength:

E 20BE prim eV 1017 eV

sin cos e R / R0V

m

B Bandwidth MHz 40 MHz angle to magnetic field of earth

= angle to zenith

R0 110 m at 55 MHz

R = distance to shower core (R/R0 1)

PE 1

2

Uantenna2

Zantenna

1

2

E 2

0

2 Gantenna

4Uantenna voltage at antenna

Zantenna impedance of antenna = 50 = frequency = 5 m at 60 MHz

Gantenna 5,5 dBi

E primthr U thr mV 5E15eV (sin,cos = .5)

Usignal GelectronicUantenna 312Uantenna

Sensitivity



Future: Test-field for Auger North• Installation of several triangle LPDA

setups in Argentina (shifted to Oct. 2006, financial situation), optimize l,L between 65 to 800 m

• Detailed proposal at next spring• Radio will give very useful comple-

mentary information: Energy• Self trigger is possible• choice of antenna may limit the

obtainable E-resolution • radio is a cost-effective option for

– Auger S&N– detector for space weather– But is also an excellent lightning detector

(as Fluorescence Detector) …

Calibration, GPS,DAQ-Container

near to a power-line at Loma Amerilla

lL

Why Radio? Why something new? Choice of antenna Background Sensitivity Self-Trigger Future

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Transcript of Why Radio? Why something new? Choice of antenna Background Sensitivity Self-Trigger Future