This paper proposes a radio-protected area (RPA) estimation model that achieves full protection and avoids overprotection by adding an appropriate margin to the extended-Hata (EH) model, for realizing efficient spectrum sharing in the V-High-band. This additional margin, called location gain, is a location-dependent value that accounts for knife-edge losses calculated from topographic information. This study experimentally obtains the location gain by conducting VHF-band-based propagation experiments in urban and suburban areas. Subsequently, we developed an estimation formula for the location gain using topographic data, which include correction terms based on the experimental data. As a result, RPA can be estimated using only the topographic data, excluding the need for propagation experiments. The proposed model resolved the problems of the EH model (incomplete protection) and free-space (FS) model (overprotection). In urban and suburban areas, the proposed model achieved full protection and over 99.7% reduction in the RPA size of the FS model when the threshold of the received power for determining the RPA was set to -80 dBm.