Conjugate heating effects associated with the upcoming Arecibo heater facility are studied using the NRL ionosphere model SAMI2. A density-dependent, localized heating source is included in the electron temperature equation to model ionospheric radiowave heating. Heating effects are examined as a function of the heating timing and the peak density of the unmodified ionosphere (through the F10.7 index). The simulation results suggest that field-aligned duct formation occur during periods of relatively low electron densities (e.g., during the night). The enhancement of the electron temperature and electron density in the conjugate topside ionosphere (∼500 km) could reach respective values of ∼5% and 25%. Heating losses associated with inelastic electron-neutral (N2) collisions primarily inhibit conjugate effects.