Compact Ku-Band OMUX with a high number of channels

As the telecom satellites become larger and larger the number of channels to be accommodated is increasing steadily. This results

in output multiplexers (OMUX) with a higher number of channels and a larger footprint often together with operating power levels which are still increasing. The ideal output multiplexer has all the properties listed below:

– small footprint

– low mass

– insert positions which do not depend on the multiplexer optimisation or channel centre frequencies or bandwidth, but only on the number of channels required, thus allowing to freeze insert positions at the very beginning of the design phase

– lowest losses for the channel filters and the manifold in order to optimise the electrical performance (low self heating, therefore lower absolute drift) and to minimise the heat flux to be covered by the heat pipes

– all housings, waveguides, baseplate made of aluminium in order to improve the heat flux and to avoid any thermomechanical stress

– all input ports well accessible, sufficient space in order to be able to mount the waveguides without any problems – this is contradictory to the requirement for a minimum footprint.

– Design optimised for good manufacturability and assembling (e.g. Aluminium half shell design) and therefore low cost and reduced delivery time

– all frequency plans within Ku transmit band should be realisable

– channel filter order and filter function type can be chosen individually for each channel (e.g. asymmetrical filter function)

– temperature compensation for the channel filters

– electrical properties of the manifold independent of the temperature

– high power handling capability covering most customers’ needs

– low insertion loss, low in band parameter variation, but providing required near band rejection

The output multiplexer proposed here will be designed in order to come as close as possible

to all design goals listed above.

The key issues are:

– Dielectric material with low losses and high thermal conductivity

– Using of dual mode resonator if possible

– Thermal compensation

The filter CDR was declared successful based on two different concepts. The first concept was based on a single mode cavity loaded with dielectric with permittivity of 10. The second solution was based in a dual mode cavity loaded with dielectric with permittivity of 24. Lately the solutions were re-considered due to the unacceptable high temperature in the Concept 2 and the large dimensions of the Concept 1 design (less market opportunities)

By combining the advantages of both concepts an innovative solution was found which will be followed up in a different program. Therefore the actual program has been stopped at this point.