PAGE CONTENTS
Objectives
The objective of the project was the development of a prototype to be utilized as a wideband multiport power combiner for ground terminals operating over multiple frequency bands assigned for satellite communication systems.
The activity consisted in the design, manufacture and test of a power combiner prototype of 16 input ports exhibiting low insertion loss over the multiple frequency bands.
The developed prototype combiner is consistent with high RF power handling thanks to the interface architecture that enables modular integration.
Challenges
The achieved key improvements of the project were:
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Expanding the bandwidth of current state-of-art multiport microwave power combiners.
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Enabling the use of a balanced set of wideband amplifiers covering different operational bands.
System Architecture
Design phase was based on the investigation of three different architectures, two based on wideband TEM combiners covering the entire band, and the last one based on a novel multi-band combiner that operates in the four bands, namely:
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Wideband Conical TEM Combiner.
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Wideband Radial TEM Combiner.
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Multichannel Multiband Combiner.
The three architecture solutions showed good performances and they were traded off to find the optimal design. To minimize manufacturing tolerance impact, the conical combiner, and the size of the multi-band combiner, indicated that the wideband solution was the best choice.
The selected combiner was composed of three main parts: a telescopic coaxial transformer, used to match the common output port, a cylindrical parallel plate region, and 16 arms realized as double ridge waveguides, which were carefully designed. Theoretical developments demonstrated that graceful degradation was related to input and output ports matching rather than ports decoupling, and the combiner was optimized accordingly. Furthermore, a custom coax-to-double ridge waveguide was designed to respond to the agency’s requirement for coaxial input and output ports.
The combiner was manufactured and tested showing a good matching to the agency requirements.
Plan
Project has been completed.
Current Status
Tests on the combiner prototype showed that the output common port return loss was better than 10 dB in all the bands and that the overall combining efficiency was better than 85% for C, X and Ku bands and 80% at Ka-band. Evaluations demonstrated that considering the presence of the 16 amplifiers integrated into each of the double ridge waveguide arms, the efficiency of the combiner would be higher than 70% also in the case of a failure of one amplifier.
Project has been completed.
