In this paper, we report on the transmission characteristics of transformers of a RF splitter widely used in CATV systems. From the point of view of broadening the splitter's operating frequency, the relationship between the RF transformer's transmission characteristics and design parameters has been investigated using computer-aided engineering. Based on the calculations, a sample device has been fabricated to confirm the theoretical results. It has been found that the configulation of the transformer winding is the most important factor affecting device performance. By selecting the appropriate winding, excessive loss can be suppressed to less than 1.6 dB and 3 dB in a frequency range of 20 MHz to 2,600 MHz for the cases of 2-way and 4-way splitters, respectively.