Geolocation of Radio Frequency (RF) emitters, is finding the geographical location of said emitter. This thesis explores the concepts of geolocation, specifically, Space-Based geolocation of earth-surface emitters by means of measuring the Angle-of-Arrival using a Uniform-Rectangular Antenna Array. Initially the literature is explored, the significance of Geolocation is made clear and the research outline and scope is defined. Afterwards, Angles-of-Arrival finding algorithms are investigated and implemented, specifically the subspace algorithms: "MUltiple SIgnal Classification" (MUSIC) and "Estimation of Signal Parameters via Rotational Invariance"(ESPRIT). These algorithms are thoroughly explained, a model is obtained and implemented into a Simulation framework. The Simulation Framework is used to create a Graphical Tool used to calculate performance figures of Space-Based Geolocation. By using the obtained Simulation, a sensitivity analysis is produced. This sensitivity analysis observes the effect of design parameters of a satellite platform and geolocation payload on the geolocation performance. This sensitivity analysis is used to find the optimal approach when designing a geolocation payload. This approach can be used to synthesize a geolocation payload design that maximizes performance.