Public cavity input multiplexer

The present invention relates to a public cavity input multiplexer that is used to divide broadband signals into multi-channel narrowband signals according to the frequency and includes a public cavity and at least two channel filters. The public cavity is a broadband resonator that is used to input broadband signals, and is coupled with each of the channel filters respectively. In the input multiplexer of the present invention, no electric cable or waveguide and circulator are used for connection. The integrated design is achieved by establishing the public cavity and the channel filter, which reduces volume and mass, avoids the errors caused by influence on the circulator due to temperature change, enhances reliability, saves cost, and improves the electric performance. The design of the public cavity makes the input coupling accurate to calculate, convenient tuning and optimizes the consistency of channels.