Overview
Large Loop Antenna System according to CISPR 16-1-4 with 3 independant orthogonal loops with 3 m diameter and coaxial switching unit to measure the magnetic fieldstrength. The loop antennas are mounted on a non conductive support stand, equipped with a coaxial switch to select one of three loops. Ferrite braid chokes are supplied with the loop antenna system to supress unwanted sheath currents, which exceed the CISPR 16-1-4 requirements by far. Self resonances of the large loops are supressed by two resistive antenna slits per loop. The coaxial switch allows both, manual switching and remote switching by the EMI-receiver and software. The loop antenna system is intended for the use inside buildings.
Schwarzbeck HXYZ 9170 Application
The three axis loop antenna system measures the current induced in the loop caused by radiated magnetic fields. A typical application is the measurement of radiated disturbances of lighting equipment according to EN 55015 / CISPR 15 in the frequency range from 9 kHz to 30 MHz. The EuT is placed in the middle of the loop antenna system, with a minimum separation of 0.3 m. The cables of the EuT should leave the loop antenna system through one octant with a minimum separation of 0.4 m to any ring of the antenna. The voltage readings of the receiver in dBµV must be reduced by the relative sensitivity of the 3 m loop antenna to obtain the induced currents, referred to the 2 m loop antenna. Further details are described in CISPR 16-1-4 and CISPR 15.
Schwarzbeck HXYZ 9170 Schematic Drawing
According to EN 55015 / 4.4 the magnetic field strength of flourescent lighting luminaires has to be measured, if the operating frequency is above 100 Hz. The measurement is done with a triple loop antenna as shown above. The Unit under Test is positioned under operating conditions in the centre of the triple loop antenna. To measure the magnetic field strength without turning, there are loops in X-,Y- and Zdirection. A current transformer converts the loop current into an appropriate voltage. Ferrite chokes reduce braid current on the coaxial cables which would cause wrong measurement.
The switchbox gives access to one of the three loops via local or remote control. The r. f.-output is connected to the input of an interference measuring receiver. The calibration balun HFCD 9171 substitutes the E.u.T. during calibration. A signal generator may be used as source for the balun. An ideal instrument for measurement and calibration is the Schwarzbeck interference measuring receiver FCKL 1528 with the optional tracking generator, which is also best choice for measuring the insertion loss of luminaires.
| Schwarzbeck HXYZ 9170 Triple Loop Antenna Technical Data | |
| Principle | Three loops with current transformers acc. to EN 55015 |
| Loop diameter | 2 m |
| Loop Material | PVC-plastic |
| Construction | The three loops are clamped to each other mechanically with plastic clamps on the crossing points. The loops are fixed to a massive ground plate via rectangular glass fibre tubes. Additional struts for best stability and ruggedness. |
| Height | Max. 2.55 m |
| Width | Max. 2.10 m |
| Current transformer | Precision toroid transformer, frequency range 9 kHz-100 MHz in a metal box with BNC conn.. Ferrite absorbers in 3 coaxial cables. |
| Calibration-Dipole (Balun) HFCD 9171 | |
| Principle | Coaxial constant current loop for calibration of the HXYZ 9170 acc. to EN 55015/B.4. |
| Construction | Coaxial cable fixed to a plastic plate. Metal box with BNC-conn. |
| Switchbox | |
| Principle | R.f.-switch to select 1 of 3 loops |
| Control | Manually via rotary switch, remote control via a 9-pin sub-d-connector 4 LEDs to monitor the state. |
| Attenuation of selected path | <0,5dB 9k-30MHz |
| Leakage from other paths | >45 dB 9 k-30 MHz |
| Construction | Metal box with 4 BNC-connectors and remote control connector. 4 LEDs. Box can be mounted on the glass fibre tube. |
| Ordering information | |
| Basic set HXYZ 9170 | 3 loops with current transformers and fixing clamps |
| Stand | Glass fibre tubes, struts, ground plate. |
| Switchbox | Selector manual and remote control, 3 coaxial cables with ferrite chokes. |
| Calibration dipole (balun) | HFCD |
Schwarzbeck HXYZ 9170 Important Note
- The loop antenna consists of 3 loops and 3 current transformers and the mechanic clamps for the fixing of the loops. (Basic components)
- The stand for mounting the loops on the floor (glass fibre tubes, struts, ground plate) are optional.
- The switchbox for both manual and remote control operation is optional.
- The calibration dipole HFCD 9171 is optional.
- The wiring (coaxial r.f.-cables, remote control cable) are optional.
