Abstract
Deforestation is occurring at a rapid rate in the tropics due to farming, mining and logging. Tropical deforestation is difficult to monitor from satellite altitudes using optical and infrared methods with cloud cover. Spaceborne RADAR is ideal because of its ability to penetrate all weather conditions. The purpose of this research is to investigate a cost-effective antenna design for pulsed and Linear Frequency Modulated Continuous Wave (LFMCW) small satellite RADAR. System configuration for both pulsed and LFMCW SAR methods were found to produce the same minimum antenna area. Three cost factors have been identified; launch, deployment and manufacture. These lead to the smallest antenna area with minimum atmospheric effect at X-band. However a higher frequency gives a smaller coverage area and the larger aspect ratio is desired. Among the main antenna structures, the phased array has the greatest potential to give the lowest overall height for a large aspect ratio. The multimode horn element is selected for its ability to increase efficiency with increase in aperture size. This advantage helps in reducing the number of elements in the array but there is the disadvantage of a larger horn height. Current methods for horn height reduction have depended on the optimization of the modes' generation from the horn structure. The novelty of this research is to show that mutual coupling can be used to reduce the horn height without losing gain. To demonstrate the advantage of mutual coupling, the isolated horn's performance is compared. The analytical Solymar and mode matching model are used to implement the isolated horn strategy. Mode matching and commercial HFSS simulation results are then used to demonstrate that mutual coupling increases element gain in the array. This allows 0. 4 l. height reduction for the 3l x 3l element in the infinite array at centre frequency 9. 6 GHz and produces a smaller physical volume to the highest frequency at 10. 2 GHz.