A microwave broadband triplexer used in satellite television systems

This paper presents the plane type triplexer. Consists three band-pass filter designed at 1.2/1.9/2.75 GHz. Bandwidth is 500 MHz. Maximum size is 47.5 × 23 mm². This triplexer is applied on commercial set-top box (STB). Characteristic impedance is 75 ohm. The first part is analysis the common filter types and use Chebyshev type II to simulate each filter. Second, combine three filters by shunting way. It has to prevent signal flow at the center frequencies of the other two filters. As a result, combine three networks can accomplish the required characteristics for a triplexer. Finally, show the simulation result and verify the property. The simulated results and measurements of the filters are not similar. We propose a better way to improve and fabricate it.