A feed horn assembly includes a tubular horn body, a film and a sealing structure. The tubular horn body has a first end and an opposite, second end. The first end includes a peripheral groove defined by an inner peripheral portion and an outer peripheral portion. The film covers the first end. A peripheral bending portion and a periphery portion of the film are disposed inside the groove. The sealing structure is disposed in the groove, and includes a first sealing component urging against the peripheral bending portion and the periphery portion of the film, and a second sealing component urging against the peripheral bending portion and the first sealing component. The outer peripheral portion has a peripheral chamfer portion formed by crimping. The peripheral chamfer portion urges against the sealing structure, such that a sealed condition is formed between the film and the inner peripheral wall.