The solar magnetic field that extends through the chromosphere is thought to expand through the transition region into the corona. The strong flux concentrations are located within the boundaries of supergranular convection cells. These boundaries form network lanes, observed in emission lines as bright lanes with varying width throughout the solar atmosphere. These network field concentrations are surrounded by mixed-polarity magnetic field with a scale of the granule diameter, as suggested by observations. We use potential magnetic field extrapolations on synthetic magnetograms to study the magnetic network topology and the effects of background magnetic field on the network expansion through the solar atmosphere. We find that the background magnetic field has a considerable effect on the ratio of network area over field of view. Furthermore we find that the expansion of the network boundaries with height deviate significantly from well-assumed funnel model expansion.