ANT/7

Magnetic Antenna

DESCRIPTION

The ANT/7 is a low-noise magnetic field sensor designed for magnetotelluric investigations and other applications where measurements of the field at frequencies below 1 Hz are required. Using Triple-Nested magnetic feedback amplifier technology and including carefully designed mu-metal cores, this antenna is designed to be a highly flexible instrument, built to withstand the difficult conditions encountered in the field environment.

SPECIFICATIONS FOR THE ANT/7 MAGNETIC ANTENNA

Dimensions

• Length: 63.5 cm (25.0 in)
• Diameter: 4.8 cm (1.875 in)
• Weight: 2 kg (4.5 lb)

Power Specifications

• Power requirement: Internal batteries 2 × 9V, or external power ±7.5 V to ±15 V, 4.5 mA
• Approx. 125 hours run time with batteries
• Inrush current: <25 mA for 5 ms with external power supplies

Output Specifications

• Output: Differential analog output, 24 to 56 Vpp depending on supply voltage
• Will drive 300 m (1000 ft) or longer cable ±4 mA max load

Frequency Specifications

• Standard Frequency Range: 0.0001 – 240 Hz
• Sensitivity in Passband: 100 mV/nT
• Highpass: 0.25 Hz, 1 pole filter (useful down to 10,000 seconds)
• Lowpass: 1 kHz, 3 pole filter

Noise Level

• 100 fT/√Hz at 1 Hz
• 12 fT/√Hz nominal > 1 Hz

Application: MT / CSEM

OPTIONS

The following parameters can be adjusted to customer requirements:

• Highpass can be set as low as 0.05 Hz
• Lowpass can be set as low as 10 Hz
• Output sensitivity can be set between 10 mV to 500 mV/g
  • 500 mV/g recommended for seafloor applications