European Space Agency

DETAILED DESIGN OF A Ka & Ku-band MPA SYSTEM

Objectives

 The overall objective is to develop MPA products operating in Ku-band or in Ka-band.MPAs have been successfully implemented by Astrium at L-band and S-band. Implementation at higher frequencies is even more challenging, particularly with regard to achieving and maintaining an adequate MPA port-to-port isolation performance.

 
The purpose of Phase 1 was to consolidate the baseline design and technical specifications, and to identify and quantify the technical risks before entering into the development of an MPA product. The purpose of Phase 2 will be to develop the product to the level that it is ready for commercial exploitation.

Challenges

The key issues of the study were:
The design of the architecture of the MPA, taking into consideration aspects such as thermal, mechanical, reliability, redundancy, mass and power.
To arrive at a commercially viable calibration method – acceptable to customers.
To define the new products and arrive at realisable manufacturing solutions; of these, the following were novel concepts: 1) Gain and Phase Adjustor & 2) INET and ONET

To liaise with operators and ensure the overall system aspects are conducive to their future business. 

Benefits

This study into Ku and Ka-band MPAs has fulfilled the original purpose of the project and has the benefits that it has been able to consolidate the baseline design and issue a detailed set of technical specifications for all the equipment of a future MPA. Moreover, the study has been able to identify and quantify the technical risks that have to be addressed before entering into the development. Detailed design and specification activities have been carried out in this study for a family of MPAs, which include both 4 x 4 and 8 x 8 MPA configurations.  A redundancy scheme has been derived for both 4 x 4 and 8 x 8 networks. A ground-based calibration scheme has been derived and shown to be the most cost effective and suitable. An AIV development plan has been created which has addressed the overall testing philosophy, the equipment required, the definition of activities, the test system and supporting software.

Features

The architecture of the MPA consisted of an Input Network (INET), TWTAs, Linearisers, Output Network (ONET), low power redundancy ring, high power redundancy ring, gain and phase adjusters and a calibration system. MPAs of order 4x4 and 8x8 were investigated. The active channel amplifiers where chosen to be prior to the INET. An option was that other channel amplifiers could remain within the MPA as part of the MPM, prior to the linearised TWTAs, but with their fixed gain mode in operation. The output ports of the MPA are directly connected via waveguide transmission lines to the antenna elements of an array fed reflector. Each output from the MPA could therefore produce a signal with the power and capacity for a radiation pattern. A 4x4 MPA is shown in figure 1. 

click for larger image

Plan

To refine the business plan, including the identification of reference applications and the establishment of satellite operators requirements.
To produce designs for Ku and Ka-band MPAs, including the selection and optimisation of a subsystem for error compensation.
Identify and if necessary breadboard any critical components in order to quantify their performance and mitigate risks.
Produce detailed specifications for the overall MPA and for each MPA component.
Produce a development plan, including component suppliers and a viable basis for industrialisation.

To establish a viable hardware cost basis for implementing an MPA EQM. 

Current status

The project achieved the original objectives to examine the design, performance and implementation of Ku/Ka-band MPAs. The project documentation and final review have successfully been completed.

A final Ka/Ku-band MPA design was achieved during the study that was in a state ready to proceed into the manufacturing phase.  Supported by additional Astrium funding external to the study discussions with suppliers began and proof of concept INET, ONET and phase adjusters have been constructed and measured, the results of which are remarkable.
This project is now complete and Astrium is planning to proceed with a new phase of work aimed at the development of a MPA demonstrator. 

Status date

Thursday, December 19, 2013 - 16:12