A multiplexer includes a microstrip manifold, and a filter bank having at least two output filters. The multiplexer channelizes an input radio frequency (RF) band of electromagnetic energy into a set of output channels by way of the filter bank. The microstrip manifold has an input port that receives an input RF signal, and at least two output ports. The microstrip manifold distributes the input RF signal to each output port, each said output port being coupled to a respective one of the at least two output filters. The multiplexer may be an input multiplexer for a spacecraft communications payload system.