  The slow and dense wind from a symbiotic red giant can be significantly
deflected toward the orbital plane by the gravitational pull of the companion
star. In such an environment, the ionizing radiation from the companion creates
a highly asymmetric HII region. We present three-dimensional models of HII
regions in symbiotic S-type systems, for which we calculate radio maps and
radio spectra. We show that the standard assumption of spherically symmetric RG
wind results in wrong shapes, sizes and spectra of ionized regions, which in
turn affects the observational estimates of orbital separation and mass loss
rate. A sample of radio maps and radio spectra of our models is presented and
the results are discussed in relation to observational data.
