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The effect of radiation pressure compression (RPC) on ionized gas in ActiveGalactic Nuclei (AGN) likely sets the photoionized gas density structure. Thephotoionized gas free-free absorption and emission are therefore uniquely setby the incident ionizing flux. We use the photoionization code Cloudy RPC modelresults to derive the expected relations between the free-free emission andabsorption properties and the distance from the AGN centre, for a given AGNluminosity. The free-free absorption frequency of RPC gas is predicted toincreases from $\sim$100 MHz on the kpc scale, to $\sim$100 GHz on the sub-pcscale, consistent with observations of spatially resolved free-free absorption.The free-free emission at 5 GHz is predicted to yield a radio loudness of$R\sim 0.03$, below the typical observed values of $R\sim 0.1-1$ in radio-quietAGN. However, the flat free-free radio continuum may become dominant above 100GHz. The suggested detection of optically thin free-free emission in NGC 1068,on the sub pc torus scale, is excluded as the brightness temperature is toohigh for optically thin free-free emission. However, excess emission observedwith ALMA above 150 GHz in NGC 1068, is consistent with the predicted free-freeemission from gas just outside the broad line region, a region which overlapsthe hot dust disc resolved with GRAVITY. Extended $\sim$100 pc scale free-freeemission is also likely present in NGC 1068. Future sub mm observation of radioquiet AGN with ALMA may allow to image the free-free emission of warmphotoionized gas in AGN down to the 30 mas scale, including highly absorbedAGN.

Radiation pressure confinement -- V. The predicted free-free absorption and emission in active galactic nuclei