CALMOPLA (CALibration with a MOnocone on a ground PLAne) is a tool for the calibration of low sensitivity, electric or magnetic field probes. The device works in the microwave range, from several tens of MHz to several GHz. It consists of a small conical monopole (D-dot), positioned at the center of a ground plane and emitting electromagnetic waves. Close to the reference plane, the radiated signals are quasi spherical waves which can be described by well known analytical expressions. The time expression of an electromagnetic field at a point in space depends on the distance between the point and the monopole: in the case where the wavelength of the emitted wave is much larger than the size of the monopole, the border between the far field (time second-derivative response) and the near field (time proportional response) is given by the wavelength divided by 2π. A vector network analyzer is sufficient to cover the frequency range of most of the sensors to be calibrated. Nevertheless, the use of a low noise amplifier and a low frequency power amplifier allow to extend the measurement range to a very low sensitive sensor anywhere on CALMOPLA.
展开▼
