The Technical University of Cartagena

Students Design a Novel Ku-Band Multiplexer 



The Technical University of Cartagena (UPCT) is the youngest technical university in Spain. This fact is contrasted, however, by its long history as a university in the engineering and business fields, as several of its faculties date back to the late 19th and early 20th-century. This unique status blends youth and tradition, making it a dynamic and innovative institution.


Multiplexers, which are used for multiple RF channel separation/combination at the input/output of front ends, are a key part of communication satellite payloads. Their performance significantly impacts the overall satellite system. The waveguide technology that is commonly used has low-loss and high-power handling capability. The objective of this multiplexer design project was to employ a complex filter topology as channel filters for the multiplexer. Although many complex topologies are used for RF/microwave industry, the novelty of this design was the all-inductive technology that resulted in a simpler manufacturing process and faster design times.


The design team chose the NI AWR Design Environment platform, specifically Microwave Office circuit software, to design a three-channel, non-contiguous multiplexer at Ku-band (11 GHz) using a manifold configuration. The software was chosen because simulations and optimizations are quite fast. Defining and working with sub-circuits is also straightforward enough to develop a large-scale equivalent circuit model for any N-channel multiplexer. The team defined the channel filters (coupling matrix, frequency plan), set up the equivalent circuit in Microwave Office software, and then optimized the channel filters employing a stepped iterative process using the lengths of the stubs and the connections between junctions. They repeated this process until the design met desired specifications.

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