Meteorological observations may be more profoundly exploited by digitalization and the application of modern statistical methods. These techniques impose more rigorous conditions on the measuring devices; the results may be biased by aliasing or by the frequency response of the measuring instrument itself. Most heat fluxmeters, used in radiometry, do not respond in the same way as a filter with lumped parameters and as a consequence the compensation of their frequency response by electronic filtering is not straightforward. A method to approach the response of this type of sensor by a filter with judicious chosen poles and zeros is described and compensation is obtained by the inversion of this filter. In this way the bandwidth of a particular thermal fluxmeter was increased from 0.07 to 5 Hz.