An active loop antenna can be utilised for emissions measurements during compliance testing according to ANSI C63.4, and most EN, CISPR and ETSI standards. Our AL-130 model has a frequency range of 9 kHz up to 30 MHz.
Also referred to as a 'magnetic loop antenna', this unique test antenna has the ability to measure E-Fields (electric fields) and H-Fields (magnetic fields).
The AL-130 has a built-in preamplifier, making it an active antenna, with improved measurement sensitivity and overall signal-to-noise ratio. It is optimised for open-field emissions testing and for regulatory compliance measurements such as FCC 18, CISPR 22, CISPR 16-1-4 and many more.
In the majority of EMC test applications, the receiving loop antenna should be positioned 1 metre off the ground with its plane vertical with the centre-point of its antenna. This gives it enough space to rotate and take measurements between horizontal and vertical polarisation.
You can accomplish this using our rotatable AT-220 or AT-812 antenna tripods which are both compatible with the only active loop antenna we currently have available on our website – the AL-130. With the AT-220 antenna stand you can mount the antenna from 1 metre to 1.2 metres, which means its antenna loop can be raised from 0.95 metres all the way up to 1.35 metres (or from 1.08 metres to 1.58 metres with the AT-812 tripod). Also, our AL-130 model has ¼ inch x 20 mounting holes, which make attachment to the AT-220 tripod or AT-812 tripod really easy.
Our active magnetic loop antenna is individually calibrated to IEEE 291 regulation (1 metre distance) and is traceable with NIST. We provide the appropriate certificate and data with the product. ISO 17025 accredited calibration can also be provided upon request.
For our customers we provide you with an exclusive 3 year guarantee on your order.
One of the more bizarre benefits of using a pre-amplified loop antenna is its accurate measurement capabilities – even when in the presence of the human body. This is because the human body is slightly conductive and has a large value for permittivity. This permittivity affects E-Fields and tunes the antenna's response down in frequency. The conductivity of the human body also absorbs energy from antennas, which can degrade their efficiency (which affects dipole antennas the most). These electric fields are considerably strong when close to an antenna, but magnetic fields give rise to antenna radiation which is more immune to the body. Because the antenna works like a 'dual' dipole, it measures strong magnetic fields in the near field of its antenna – explaining its robustness in regard to performance level.
Furthermore, an active loop antenna with a perimeter of one wavelength acts in the same way as a folded-dipole antenna. Although, it has an impedance that is higher than a half wavelength dipole antenna's impedance.
Interestingly, a loop antenna doesn't need to have the shape of a perfect circle. Although if you meander the shape of the loop; this results in the electric current being slightly cancelled and makes the antenna less efficient (and negatively affects its bandwidth). As a rule, if the antenna gets larger, it becomes more efficient – this is what makes our AL-130 model the perfect active loop antenna for accurate open field emissions testing below 30 MHz.