General Purpose Anechoic Chamber

Opened in 1995, this 9 metre long with 3m by 3m cross-section microwave and millimetrewave anechoic chamber is capable of measuring the radiation characteristics of feeds and small millimetrewave antennas up to 500 GHz.

The chamber is of an unusual design in that it has several modes of operation. In its first mode it can operate as a conventional far-field anechoic chamber of length 9 metres. However, with the deployment of a movable dividing screen it can be converted into two ranges: one providing a 6 metre long far-field anechoic chamber, the other providing a plane polar Near-field / Far-field chamber capable of measuring reflector antennas up to about 1.5 metres in diameter with operating frequencies to 40GHz.

The antenna positioners provide test antenna azimuth and polarisation rotation, the so called "model tower" axes, and polarisation rotation of the source antenna. All 3 axes operate under computer control providing facilities for automatic antenna pattern measurement. Antenna alignment is provided by a collimating optical telescope and optical flat, enabling low cross-polarisation feeds to be accurately aligned and therefore measured.