Wide-band harmonics and spurious characterisation of a C-band High-Power Amplifier

The MetOp-SG SCA HPA output spectrum has been characterized for harmonic and spurious emissions in the continuous frequency range 7.5-40 GHz, using a novel measurement method. The key principle of the method is to radiate the HPA emissions from a horn antenna, and to then spatially sample the resulting near field, eventually integrating the measured power into a frequency spectrum. This approach combines high sensitivity with high accuracy, and overcomes the principal uncertainty problems, which inherently arise when attempting to measure spectral power in over-moded RF transmission lines.