Compact Antenna Test Range

Because MilliBox antenna test systems are modular, the antenna measurement distance can be adjusted to fulfill the requirement of the device-under-test (DUT) far-field dimension. Far-field distance is the minimum measurement distance between the test probe and the DUT for a given antenna. The far-field distance of an antenna or a phased array is simplified as 2D²/λ, where D is the aperture size and λ is the wavelength of the antenna. The far-field distance increases with the frequency and with the antenna aperture size.

For longer range applications such as satellite communications and some radars, the far field distance may be longer than the anechoic chamber or even longer than the entire building. In this situation, you need to consider a compact antenna test range (CATR) like MilliBox MBX32CTR to be your best option forward.

CATR is a type of over-the-air (OTA) antenna testing chamber where a parabolic reflector abstracts the far-field requirement. Very much like a parabolic antenna for satellite TV, CATR systems consist of the combination of the parabola and the probe being at its focus point. When the alignment of the probe coincides with the focal point of the parabola, the DUT is perceived at an infinite distance because all incident signals are parallels. This is because the parabola natural mechanical properties convert a spherical plan wave into a flat plane wave, hence playing the role of a near field to far field converter.

When your RF design needs to be tested over the air, you need to determine your far-field distance, based on this, you may be able to use direct far field measurement methods with MBX0xor MBX3x systems, otherwise MBX32CTR Compact Antenna Test Range system may be your best options.