In this study, a comprehensive approach for the experimental assessment of the absorbed power density (APD) is developed. The method includes several novel components: (i) a specialized probe, (ii) a composite phantom, (iii) a reconstruction technique, (iv) a calibration method, and (v) a validation process. The described solution has been developed for the frequency range from 24 to 30 GHz, but can be extended to all frequency bands between 10 and 45 GHz. A novel composite phantom emulates the reflection and transmission coefficients of human skin for propagating and evanescent modes, while its increased penetration depth, in comparison to dermis tissue, enables the measurement of the induced electromagnetic fields (EMFs) with a new miniaturized dosimetric broadband probe. The implementation has a wide dynamic range and sufficient spatial resolution to use it for type approval of mobile devices. Its probe is calibrated with low uncertainty in a novel, traceable setup. A set of reference antennas with known numerical target values for the APD has been compiled to validate the measurement system. The validation demonstrates that the deviation is within the expanded uncertainty of 1.6 dB for pAPD and  1.5 dB for psAPD.