The electromagnetic spectrum available for radio communications is a limited resource and the demand for frequency spectrum from both civilian and military users is constantly increasing with new services requiring wireless communication. With a growing army, it is not possible to make conflict-free frequency allocations to all radio systems of the Armed Forces. Since the needs for frequency spectrum exceed the available resources, some form of sharing of the available frequencies is required. There are different approaches to sharing, such as frequency sharing through geographical reuse or time sharing. The aim of this report is to show at what distances geographic frequency reuse is possible and at what distances there is a risk of frequency conflicts and how this affects the ability of hostile jammers to degrade the communication performance. The aim is also to show the benefits of geographical reuse and time sharing of frequencies in terms of, for example, increased theoretical data rates. If radio systems are close to each other, so that strong interference can occur between them, it is often better to use time sharing. At longer distances, it is more advantageous to use the same frequency spectrum simultaneously. The best strategy when systems are exposed to hostile jamming also depends on the received jamming power. This report shows that the minimum distance between two interfering radio systems required to avoid performance degradation, depends on the design of the systems, e.g. frequency range and required data rate or signal quality. The analyses show that the required distance between two radio systems for geographic reuse of the frequency spectrum is about 2-5 times larger than the communication distance within the respective network. For frequency hopping radio systems, orthogonal frequency hopping alone is not sufficient to make the interference between two different co-located radio networks managable. Rather, an additional frequency separation is required between the frequencies currently in use if radio systems are to be co-located in close proximity to each other. Reusing the same frequency spectrum in different geographical areas is deemed necessary to meet the communication needs of the Armed Forces. Reuse of frequency spectrum creates an inevitable risk of frequency conflicts that must be managed, either by method or technology. This study has mainly considered individual links, but has not taken into account redundancy and robustness introduced in upper layer protocols. The impact on jamming protection in relation to how to best share the available frequency spectrum between radio networks, taking into account link and network protocols, should be further studied.