Near field

Category: 

Measuring antenna ranges with planar scanner

The dimensions of a conventional test range can be reduced by making
measurements in the Near-Field of the testing antenna, and then using analytical methods to transform the measured Near-Field data to compute the Far-Field radiation characteristics. Such techniques are usually used to measure patterns and gain.

The Near-Field measured data (amplitude and phase distribution) is acquired by using a probe to scan the field over a preselected plane surface. The measured data is then transformed to the Far-Field using analytical methods.

In the planar scanning technique, a probe antenna is moved in a plane situated in front of the testing antenna and the received signal (amplitude and phase) is recorded. The position of the probe is characterized by the coordinates (x,y,z0) in the xyz coordinate system of the AUT. During the scanning, z0, is kept constant, while x and y are varied.

The dimensions of the Near-Field scanning aperture must be large enough
to accept all significant energy from the testing antenna.

Technical characteristics

Parameter name Parameter meaning
Operating frequancy 0,8-50 GHz
Amplitude range >76 dB
Amplitude pattern and Gain measurement accuracy:
-in range to -25dB < 0,3 dB
-in range to -40dB < 0,45 dB
Phase pattern measurement accuracy:
— in range to -25 dB < 3,5°
— in range to -40 dB < 5°
Operating zone to 20 m