At a recent Keysight Technologies Hotspot Seminar (Surrey University) I saw a really cool setup for measuring near electric fields around antennas.
Traditionally metallic antenna probes in the Fresnel Zone have been used to do this, but now it's possible to make measurements directly in the near field using an optical quartz crystal fed with a fibre optic cable. The fibre optic cable is fed with specially modulated light and the electric field is calculated based on changes to the modulation of the reflected signal.
The benefits of using a crystal are less interference to the electric near field.
Using an automated machine the probe can scan the surrounding space of the antenna in the Ex,Ey and Ez planes. Software can then construct an image of the near field.
But, more importantly, using transformations the electric near field can be transformed (using software) to show the far field pattern. This allows for accurate antenna pattern measurements to be made in compact ranges.
Traditionally metallic antenna probes in the Fresnel Zone have been used to do this, but now it's possible to make measurements directly in the near field using an optical quartz crystal fed with a fibre optic cable. The fibre optic cable is fed with specially modulated light and the electric field is calculated based on changes to the modulation of the reflected signal.
The benefits of using a crystal are less interference to the electric near field.
Using an automated machine the probe can scan the surrounding space of the antenna in the Ex,Ey and Ez planes. Software can then construct an image of the near field.
But, more importantly, using transformations the electric near field can be transformed (using software) to show the far field pattern. This allows for accurate antenna pattern measurements to be made in compact ranges.
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