Technique speeds antenna production

A more accurate measuring technique for omni-directional antennas has been developed by the National Physical Laboratory (NPL).

Researchers at the NPL have used the technique for verifying a variety of omni-directional antennas for applications such as wireless crop monitoring and implanted medical devices.

Omni-directional antennas, such as those used in mobile phones, radiate radio frequency (RF) signals at 360°. Martin Alexander, principal research scientist at NPL, said engineers have been challenged to accurately measure these signals.

The reason, he added, lies in creating a suitable testing environment that does not reflect radiation.

All antenna measurements require a transmitting antenna and a receiving antenna.

The receiving antenna is normally connected to the measuring receiver by a coaxial cable. The receiving antenna is rotated and the cable relays information on the amplitude and phase of the RF signals over a sphere with the antenna at the centre.

Testing occurs inside an anechoic chamber and researchers can view the antenna’s 360° radiation pattern in an adjacent room on a computer screen.