Schwarzbeck HFRA 5149 H-Field Transmit Loop VLF / HF

The EMC Shop is an ISO 17025 accredited calibration company with the Schwarzbeck HFRA 5149 in stock available for sale or rental. Repair and refurbishment services available as well. Contact us now for application support.

In the VLF-HF frequency range 9 kHz to 30 MHz the magnetic field strength is measured preferably, but often expressed in the unit of the electric field strength as the "fictive E field level" ( dBµV/m).

In the undistorted far-field both units are linked by the characteristic impedance of free space 120 π? = 377 ?. Practical EMC/EMI measurements however are carried out in the near-field zone (D <0.1 λ).

For that reason defined magnetic field sources are required. For Immunity Tests powerful H fields might be needed, but also general tests and measurements at an open site, in screened rooms and in absorber-lined rooms require well-defined powerful H field sources. Magnetic fields in the near-field zone decay with the inverse 3rd power of distance (ca. 18 dB at twice the distance). Even at 1 m distance at 30 MHz the transition from pure near-field to far-field begins, the exponent of degradation gradually reduces from 3 to 1 in the undistorted far-field.

The magnetic loop antenna described here may be operated with up to 100 W input power for short periods and with 30 W continuously. An external 50 ? power termination with the proper dissipation is required. A 50 ? 20 Watt termination is part of the scope of delivery of HFRA 5149. It is more than sufficient for the maximum output of laboratory power signal generators.

The HFRA 5149 has a 3/8" camera thread at the box.